CN1701478A - Optical semiconductor device and optical semiconductor integrated circuit - Google Patents

Optical semiconductor device and optical semiconductor integrated circuit Download PDF

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Publication number
CN1701478A
CN1701478A CN 200480000980 CN200480000980A CN1701478A CN 1701478 A CN1701478 A CN 1701478A CN 200480000980 CN200480000980 CN 200480000980 CN 200480000980 A CN200480000980 A CN 200480000980A CN 1701478 A CN1701478 A CN 1701478A
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optical waveguide
waveguide
refractive index
semiconductor
slot part
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CN100377455C (en
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布谷伸浩
柴田泰夫
藤原直树
菊池顺裕
东盛裕一
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Nippon Telegraph and Telephone Corp
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Nippon Telegraph and Telephone Corp
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Abstract

An optical semiconductor device and optical semiconductor integrated circuit are provided by combining, on a semiconductor substrate, materials having different refractive indices and different temperature dependence of the refractive indices. In particular, it becomes possible to control the temperature dependence of the oscillation wavelength with a propagating region having a material and/or structure whose temperature dependence of the refractive index is different from that of a gain region of the semiconductor laser. In addition, they can be configured to have a plurality of interfaces formed along the waveguide direction of the optical waveguide so that the light reflected off the first interface is weakened by the light reflected from the remaining interfaces. Also, they can be configured with the interfaces inclined to the propagating direction so that the waveguide loss due to the reflection and refraction between the optical waveguides whose refractive indices differ from each other can be reduced.

Description

Optical semiconductor photoreactive semiconductor integrated circuit
Technical field
The present invention relates to the optical semiconductor photoreactive semiconductor integrated circuit of semiconductor laser, optical waveguide and other Optical devices etc., particularly relate to the optical semiconductor photoreactive semiconductor integrated circuit that on semiconductor substrate, refractive index and refractive index is made up the different material of the dependence of temperature.
Background technology
The vibration wavelength of semiconductor laser changes with environment temperature and component temperature.For example resemble K.Sakai, " 1.5 μ m range InGaAsP/InP distributed feedback lasers; " IEEEJ.Quantum Electron., vol.QW-18, pp.1272-1278, it is such that Aug.1982 delivers, and the vibration wavelength of distributed feed-back type (DFB) laser is about 0.1nm/K to the dependence of temperature.This is because semi-conductive refractive index (n) has the dependence to temperature, so the bragg wavelength (λ of diffraction grating B) press
mλ B＝2nΛ …(1)
Change.Wherein m is the diffraction number of times, and Λ is the cycle of diffraction grating.
For example use under the situation of semiconductor laser at light source as fiberopticscommunication, particularly (WDM: under situation wavelength division multiplexing), the precision of signal light wavelength is important at the wavelength multichannel communication that makes several wavelength optical signals multiplex on 1 fiber optics.Therefore it is indispensable making stable as the vibration wavelength of the semiconductor laser of illuminating source.Therefore for example by carry out the temperature control of semiconductor laser with Peltier (Peltier) element, can make the vibration wavelength of semiconductor laser stable.
As carry out temperature control without Peltier element, make vibration wavelength in addition, carry out big classification and can consider 2 methods the stable method of the dependence of temperature.Just first method is as H.Asahi et al, Jpn.J.Appl.phys., vol.35, pp.L875-, 1996. shown in, by using and the present specific refractivity semi-conducting material little mutually, only utilize the method for semiconductor structure reduction to the dependence of temperature to the dependence of temperature.Second method is that the composite construction of the material beyond utilizing semiconductor and semiconductor reduces the method to the dependence of temperature.For example well-known " Hybrid integrated extennal Cavity laser withouttemperature dependent mode hopping; " T.Tanaka et al, Electron.Lett., vol.35, no.2, pp.149-150,1999. shown in, the laser of the external waveguide road combination that constitutes semiconductor laser with by the material beyond the semiconductor, and open shown in the 2002-14247 communique as the spy, semiconductor with have the structure that the refractive index opposite with semiconductor is connected in series alternately to the material beyond the semiconductor of the dependence of temperature.
Carrying out with Peltier element in the temperature controlled method of semiconductor laser, existing component structure and control complicated, the problem of consumed power increase simultaneously.
Use the refractive index semi-conducting material little in addition to temperature dependence, only utilize semiconductor structure to reduce method to temperature dependence, up to now also do not have the report of new material that can practicability, develop new semi-conducting material in the growth of crystallization with make aspect the element very difficulty.
This external application makes the method for the combination of materials beyond semiconductor and the semiconductor, and hope can not wanted as far as possible simply combinations such as optical axis adjustment.Even simple manufacture method such as spin coated organic material on semiconductor substrate, semiconductor and organic material are connected in series mutually constitute under the situation of distributed reflectors, in order to make 1 diffraction grating that obtains good characteristic, it is necessary making semiconductor and mutual arrangement of organic material with the length about 1/4 wavelength, and all there are big problem in processing complexity and reliability.
By making the semiconductor light wave guide passage and being connected, can obtain having the optical waveguide of only using the unavailable new features of semiconductor on the other hand by having the optical waveguide that constitutes with the material of semiconductor different qualities.Though for example semi-conductive refractive index Yin Wendu raises and increases, just has positive temperature dependence, have the optical waveguide that the material of the temperature dependence that is lowered, just born by Yin Wendu rising refractive index is in contrast constituted and be connected in series in method on the semiconductor light wave guide passage.
Can obtain so as a whole growing the optical waveguide that does not have dependence with temperature as the optics of refractive index and waveguide road length product, as K.Tada et al. " Temperaturecompensated coupled cavity diode lasers ", Optical and QuantumElectronics, vol.16, pp.463-469,1984. that delivers is such, by constituting the resonator that constitutes by material in that semiconductor laser is outside with negative temperature dependence, can realize vibration wavelength temperature independent do not have the laser of dependence with temperature.
Just use the effective refractive index n of semiconductor medium DIncrease, the optical length n of laser resonator DL DIncrease with the temperature rising.Wherein laser diode is of coupled connections at optical length n RL RRaise on the external resonator reduces resonator integral body optical length n with temperature DL D+ n RL RRelative temperature becomes fixing condition and can provide with following (2) formula.
/T(n DL D+n RL R)
＝L Dn D/T+n DL D/T+L Rn R/T+n RL R/T＝0 …(2)
n wherein D/ T and L D/ T just is generally, n R/ T and L R/ T is for negative.
Wherein joint resemble the semiconductor light wave guide passage and the waveguide road situation that constitutes by the material beyond the semiconductor engage under the situation on waveguide road with different refractivity, reflect because of different generation of the refractive index on 2 waveguide roads at its interface.If the refractive index of first optical waveguide is N 1, second optical waveguide refractive index be N 2, consider that in order to simplify reflectivity R can provide with following (3) formula by plane wave.
R＝((N 1-N 2)/(N 1+N 2)) 2 …(3)
Under the situation of the light that external emission is propagated through semiconductor and quartz waveguide road, produce reflection because the refractive index of waveguide road and outside is different.Therefore the light of for example propagating in the semiconductor light wave guide passage is under the situation that the semiconductor laser end face is launched to air, as deliver " optics of lens " Tokai University publication meeting pp.273～288 of the thorough work in careless river, by the vapor-deposited film film forming on the semiconductor end face that makes certain specific thicknesses, can prevent reflection., be difficult to form accurately such antireflection film making the waveguide road that constitutes by different materials under situation integrated on the semiconductor substrate.
The light oblique incidence is under the situation of the boundary face of the mutual different material of refractive index on the other hand, and establishing incidence angle is θ 1, the refraction angle is θ 2, according to Snell's law (Snell ' s law), the mode of representing with following (4) formula produces refraction in this boundary face.
Sinθ 1/sinθ 2＝N 2/N 1 …(4)
Wherein incidence angle is θ 1With Brewster angle (Brewster angle) θ BUnder the consistent situation, can make the areflexia that is parallel to plane of incidence composition, Brewster angle θ BRepresent with following (5) formula.
θ B＝tan -1(N 2/N 1) …(5)
Generally in the semiconductor waveguide road, be extensive use of and imbed heterogeneous (HB) structure and ridge structure etc.And in semi-conductive etching with imbed in the growth, have the crystalline orientation that is fit to etching and imbeds.
Make semiconductor light wave guide passage and refractive index therewith under the situation of the optical waveguide coupling combination that constitutes of the different material of semiconductor light wave guide passage, because corresponding refringence is created in the reflection of joint interface, the degree of freedom of waveguide road design is restricted.
Wherein by utilizing Brewster angle θ B, the reflection between the different mutually waveguide road of refractive index is reduced, but utilize Brewster angle θ B, the boundary face refraction of light between the waveguide road has wave guide direction and becomes the problem that is not straight line.
Use Brewster angle θ in order to reduce the reflection between the different mutually waveguide road of refractive index in addition B, make the making of imbedding the semiconductor waveguide road along specific crystallization direction and become difficult, have and can not make the problem of imbedding the semiconductor waveguide road in high reliability ground.
If have again in order to reduce the reflection use Brewster angle θ between the different mutually waveguide road of refractive index B, be difficult to semiconductor waveguide road arranged perpendicular to have the problem that to use cleavage surface as the reflecting surface of semiconductor laser etc. in cleavage surface.
As mentioned above, in that refractive index is had variety of issue with it in to the different combination of materials of the dependence of temperature, wish to improve.
Summary of the invention
In order to solve above-mentioned problem, the semiconductor laser of an embodiment of the invention has: the gain regions that wavelength selectivity is arranged; With aforementioned gain regions optical coupled, effectively refractive index is to the dependence transmission region different with aforementioned gain regions, that do not have wavelength selectivity of temperature; With the reflector space that makes the light reflection of propagating at aforementioned transmission region.
Utilize the gain regions that the transmission region that does not have wavelength selectivity is coupling in wavelength selectivity like this, can control the dependence of vibration wavelength and temperature.Just gain regions is owing to have wavelength selectivity, the light of exciting specific wavelength selectively.Transmission region does not have wavelength selectivity since with aforementioned gain regions optical coupled, at aforementioned gain regions by the light of exciting directly in transmission region transmission, the phase change of transmission light.Owing to be reflected in the light that aforementioned transmission region transmits with reflector space, turn back to aforementioned gain regions again, the wavelength change that the aforementioned gain regions variations in temperature of Phase Shift Offset that causes with aforementioned transmission region variations in temperature causes.Even therefore having under the situation of material as the gain media use of vibration wavelength to the dependence of temperature, the material beyond semiconductor and the semiconductor is not carried out complex combination yet, can be controlled at the vibration wavelength of semiconductor laser to the dependence of temperature the value of hope, by using simple structure and easy method for processing, can make the vibration wavelength of semiconductor laser stable.
The semiconductor laser of other execution modes of the present invention has in addition: the gain regions that wavelength selectivity is arranged; With aforementioned gain regions optical coupled, the effective refractive index material different with aforementioned gain regions to the dependence of temperature arranged, there is not the transmission region of gain and wavelength selectivity; With the reflector space that does not have gain that makes the light reflection of propagating at aforementioned transmission region.
Can not use new material with formation transmission regions such as the organic materials that can obtain like this,, can control the dependence of vibration wavelength temperature with simple structure and easy method for processing.
In addition, the semiconductor laser of other execution modes of the present invention has: the gain regions that wavelength selectivity is arranged; With aforementioned gain regions optical coupled, the effective refractive index structure different with aforementioned gain regions to the dependence of temperature arranged, there is not the transmission region of gain and wavelength selectivity; With the reflector space that does not have gain that makes the light reflection of propagating at aforementioned transmission region.
Do not use the effective refractive index material different like this, can constitute transmission region,, can control the dependence of vibration wavelength temperature with simple structure and easy method for processing to the dependence of temperature.
In addition, the semiconductor laser of other execution modes of the present invention has: first gain regions that wavelength selectivity is arranged; With the aforementioned first gain regions optical coupled, have at least a in the dependence of temperature material different or the structure of effective refractive index with aforementioned gain regions, there is not the transmission region of gain and wavelength selectivity; With with aforementioned transmission region optical coupled, have second gain regions of wavelength selectivity.
Can constitute transmission region with the material that organic material etc. can obtain like this, there is no need a speculum simultaneously and use as reflector space.Therefore new material is not used in the integrated easy realization of monolithic of semiconductor laser simultaneously, with simple structure and easy method for processing, can control the dependence of vibration wavelength to temperature.
The semiconductor laser of other execution modes of the present invention has in addition: semiconductor substrate; On the aforesaid semiconductor substrate, form, have the active layer of distribution catoptric arrangement; The coating layer that on aforementioned active layer, forms; The aforementioned active layer of a part and the removal zone of aforementioned coating layer have been removed; Be embedded in aforementioned removal zone in, temperature compensating layer that effective refractive index is different with aforementioned active layer to the dependence of temperature.
After removing a part of active layer and coating layer like this, can make transmission region that does not have wavelength selectivity and the gain regions coupling that wavelength selectivity is arranged easily by the filling temp layer of compensation, with simple structure and easy method for processing, can control the dependence of vibration wavelength to temperature.
The semiconductor laser of other execution modes of the present invention has in addition: semiconductor substrate; Be layered in the distributed Bragg reflecting layer on the aforesaid semiconductor substrate; Be layered on the aforementioned distributed Bragg reflecting layer, have the active layer of distribution catoptric arrangement; Be layered on the aforementioned active layer temperature compensating layer that effective refractive index is different with aforementioned active layer to the dependence of temperature; With the reflector that is layered on the aforementioned temperature layer of compensation.
Utilize sequential cascade distributed Bragg reflecting layer, active layer, temperature compensating layer and reflector on semiconductor substrate like this, can easily make transmission region that does not have wavelength selectivity and the gain regions coupling that wavelength selectivity is arranged, with simple structure and easy method for processing, can control the dependence of vibration wavelength to temperature.
The semiconductor laser of other execution modes of the present invention has in addition: semiconductor substrate; On the aforesaid semiconductor substrate, form, the active layer of distribution catoptric arrangement is arranged; On aforementioned active layer, form, be provided with the coating layer on inclined plane in aforementioned active layer end; With on aforementioned coating layer, form the temperature compensating layer that effective refractive index is different with aforementioned active layer to the dependence of temperature.
Utilize like this being provided with on the coating layer on inclined plane temperature compensating layer is set, can easily make transmission region that does not have wavelength selectivity and the gain regions coupling that wavelength selectivity is arranged, with simple structure and easy method for processing, can control the dependence of vibration wavelength to temperature.
The integrated light guide road of an embodiment of the invention has in addition: first optical waveguide; With the aforementioned first optical waveguide optical coupled, second optical waveguide that refractive index is different with aforementioned first optical waveguide; With to cross the mode of aforementioned first optical waveguide, interface apart from aforementioned first optical waveguide and aforementioned second optical waveguide only separates the slot part that predetermined distance is provided with, set apart from the interval at aforementioned interface and the width of aforementioned slot part, make hyporeflexia on the border of aforementioned first optical waveguide and aforementioned second optical waveguide.
Form groove in order to the mode of crossing (crosscut) aforementioned first optical waveguide like this, can be adjusted at the phase place of the borderline reflected wave of aforementioned first optical waveguide and aforementioned second optical waveguide, can cancel out each other at the borderline reflected wave of first optical waveguide and second optical waveguide.Even therefore under the different mutually situation of the refractive index of first optical waveguide and aforementioned second optical waveguide, also can make first optical waveguide and the borderline hyporeflexia of aforementioned second optical waveguide.Its result does not form antireflection film on the interface of first optical waveguide and aforementioned second optical waveguide, the borderline loss of first optical waveguide and aforementioned second optical waveguide is reduced, can be corresponding to optical waveguide integrated, realize having the optical waveguide of only using the unavailable new features of semiconductor.
The integrated light guide road of other execution modes of the present invention has in addition: first optical waveguide that forms on semiconductor substrate; On the aforesaid semiconductor substrate, form second optical waveguide that refractive index is different with aforementioned first optical waveguide; With the border that is configured in aforementioned first optical waveguide and aforementioned second optical waveguide, to separate the mode of slot part and vertical waveguide direction with aforementioned first optical waveguide, the semiconductor board that on the aforesaid semiconductor substrate, forms, set the width of aforementioned slot part and the thickness of aforesaid semiconductor plate, make at the light of the boundary reflection of aforementioned first optical waveguide and aforementioned slot part because of weakening at the light of the boundary reflection of aforementioned slot part and aforesaid semiconductor plate with at the light of the boundary reflection on aforesaid semiconductor plate and the aforementioned second waveguide road.
Utilize like this at the light of the boundary reflection of slot part and semiconductor board with at the light of the boundary reflection of the semiconductor board and second optical waveguide, the light at the boundary reflection of the first waveguide road and slot part is weakened.Even therefore under the situation of the optical waveguide beyond integrated semiconductor optical waveguide and semiconductor on the same semiconductor substrate, also can reduce the reflection between these optical waveguides, the degree of freedom that can keep the design of waveguide road realizes having the optical waveguide of only using the unavailable new features of semiconductor.
The integrated light guide road of other execution modes of the present invention has in addition: first optical waveguide that forms on semiconductor substrate; On the aforesaid semiconductor substrate, form second optical waveguide that refractive index is different with aforementioned first optical waveguide; Be configured in the border of aforementioned first optical waveguide and aforementioned second optical waveguide, to separate the mode of the first slot part vertical waveguide direction, first semiconductor board that on the aforesaid semiconductor substrate, forms with aforementioned first optical waveguide; With to separate the mode of second slot part and vertical waveguide direction with aforementioned first semiconductor board, second semiconductor board that on the aforesaid semiconductor substrate, forms, set the width of aforementioned first slot part and second slot part and the thickness of aforementioned first semiconductor board and aforementioned second semiconductor board, make light, because of light at the boundary reflection of aforementioned first slot part and aforementioned first semiconductor board at the boundary reflection of aforementioned first optical waveguide and aforementioned first slot part, light at the boundary reflection of aforementioned first semiconductor board and aforementioned second slot part, at the light of the boundary reflection of aforementioned second slot part and aforementioned second semiconductor board with at the light of the boundary reflection of aforementioned second semiconductor board and aforementioned second optical waveguide and weaken.
Like this because of at the light of the boundary reflection of aforementioned first slot part and aforementioned first semiconductor board, at the light of the boundary reflection of aforementioned first semiconductor board and aforementioned second slot part, the light at the boundary reflection of first optical waveguide and first slot part is weakened at the light of the boundary reflection of aforementioned second slot part and aforementioned second semiconductor board with at the light of the boundary reflection of aforementioned second semiconductor board and aforementioned second optical waveguide.Even therefore under the situation of the optical waveguide beyond integrated semiconductor optical waveguide and semiconductor on the same semiconductor substrate, also can reduce the reflection between these optical waveguides, the degree of freedom that can keep the design of waveguide road realizes having the optical waveguide of only using the unavailable new features of semiconductor.
The integrated light guide road of other execution modes of the present invention has in addition: the first fiber waveguide zone; With the boundary face in the aforementioned first fiber waveguide zone wave guide direction tilted configuration with respect to the aforementioned first fiber waveguide zone, the second fiber waveguide zone that refractive index is different with first fiber waveguide zone; With with the boundary face in the aforementioned second fiber waveguide zone on refractive direction with the consistent mode of wave guide direction, the 3rd fiber waveguide zone of configuration and the boundary face in the aforementioned second fiber waveguide zone.
The boundary face in first fiber waveguide zone and the second fiber waveguide zone is tilted with respect to wave guide direction, even under the different mutually situation of the refractive index in first fiber waveguide zone and the second fiber waveguide zone, the reflection of the boundary face in and second fiber waveguide zone regional in first fiber waveguide is reduced, and by being provided with the 3rd fiber waveguide zone of coming the configure boundaries face in the refractive direction mode consistent with wave guide direction, can reduce the waveguide path loss that causes because of the reflection between the mutually different waveguide road of refractive index and refraction and lose, can adjust wave guide direction.
Even therefore the different mutually material of refractive index is being inserted under the interregional situation of fiber waveguide, also can suppress the waveguide path loss loses, can be effectively and use the crystalline orientation that is fit to cleavage, etching and imbeds etc. neatly, the reliability that can be suppressed at when making the waveguide road worsens, realization has the optical waveguide of only using the unavailable new features of semiconductor, can improve the degree of freedom of waveguide road design simultaneously.
In addition as adopting the integrated light guide road of other execution modes of the present invention, it is characterized in that, comprise: first optical waveguide and the 3rd optical waveguide with first refractive index, be configured in the second fiber waveguide zone between aforementioned first optical waveguide and aforementioned the 3rd optical waveguide with second refractive index, the boundary face that aforementioned first optical waveguide and the aforementioned second fiber waveguide zone connect into aforementioned first optical waveguide and the aforementioned second fiber waveguide zone is not orthogonal to the direction of aforementioned first optical waveguide, on the extended line of the anaclasis direction on the boundary face in aforementioned first optical waveguide and the aforementioned second fiber waveguide zone, the boundary face that aforementioned second fiber waveguide zone and aforementioned the 3rd optical waveguide connect into aforementioned second fiber waveguide zone and aforementioned the 3rd fiber waveguide zone is not orthogonal to aforementioned extended line, and the anaclasis direction of the boundary face of and aforementioned three optical waveguide regional in aforementioned second fiber waveguide is consistent with the direction of aforementioned the 3rd optical waveguide.
Even like this under situation about the different mutually material of refractive index being inserted between optical waveguide, also can reduce the reflection on the boundary face of the boundary face in first optical waveguide and the second fiber waveguide zone and second fiber waveguide zone and the 3rd optical waveguide, and can suppress the loss that causes because of refraction.
Description of drawings
Fig. 1 is the sectional view along the structure of the semiconductor laser of fiber waveguide direction indication first embodiment of the invention.
Fig. 2 is the reflectance spectrum of the semiconductor laser of expression one embodiment of the present invention and the diagram of reflected wave phase characteristic.
Fig. 3 for the vibration wavelength of the semiconductor laser of explanation one embodiment of the present invention to the diagram of the compensation principle of temperature dependence.
Fig. 4 is the thermal refractive index coefficient difference of semiconductor laser of explanation one embodiment of the present invention and the vibration wavelength diagram to temperature dependence.
Fig. 5 is the sectional view along the structure of the semiconductor laser of fiber waveguide direction indication second embodiment of the invention.
Fig. 6 is the sectional view along the structure of the semiconductor laser of fiber waveguide direction indication third embodiment of the invention.
Fig. 7 is the sectional view along the structure of the semiconductor laser of fiber waveguide direction indication fourth embodiment of the invention.
Fig. 8 is the sectional view along the structure of the semiconductor laser of fiber waveguide direction indication fifth embodiment of the invention.
Fig. 9 A～9E is for cutting the sectional view of a kind of constructive method of the semiconductor laser of representing sixth embodiment of the invention open in the vertical light wave guide direction.
Figure 10 is the stereogram of the brief configuration of the coupling part on the integrated light guide road of expression seventh embodiment of the invention.
Figure 11 is along XI, the XII-XI of the fiber waveguide direction of Figure 10, the sectional view that the XII line cuts off.
Figure 12 is the sectional view along the brief configuration of the coupling part on the integrated light guide road of fiber waveguide direction indication eighth embodiment of the invention.
Figure 13 is the sectional view along the brief configuration on the integrated light guide road of the direction indication ninth embodiment of the invention vertical with the fiber waveguide direction.
Figure 14 is the sectional view along the brief configuration on the integrated light guide road of the direction indication tenth embodiment of the invention vertical with the fiber waveguide direction.
Figure 15 is the reflectivity of the coupling part on the integrated light guide road of expression Figure 11 and the width d of slot part A61 1Thickness d with semiconductor board B61 2The diagram of relation.
Figure 16 is the sectional view of the integrated light guide road brief configuration of expression tenth embodiment of the invention.
Figure 17 is the sectional view of the integrated light guide road brief configuration of expression eleventh embodiment of the invention.
Figure 18 is the stereogram of the brief configuration of the integrated light guide road coupling part of expression twelveth embodiment of the invention.
Figure 19 is along XIX, the XX-XIX of the fiber waveguide direction of Figure 18, the sectional view that the XX line cuts off.
Figure 20 is the sectional view along the brief configuration of the integrated light guide road coupling part of fiber waveguide direction indication thriteenth embodiment of the invention.
The reflectivity of the optical waveguide that Figure 21 constitutes with regional A132, the B132 of Figure 18, R132 for expression and the thickness d of semiconductor board B132 4The diagram represented of relation.
Figure 22 is the width d of the slot part A132 of expression Figure 18 3With diagram with respect to the relation of the reflectivity of incident wavelength.
Figure 23 is the sectional view of the brief configuration on the integrated light guide road of expression fourteenth embodiment of the invention.
Figure 24 is the sectional view of the brief configuration on the integrated light guide road of expression fifteenth embodiment of the invention.
Figure 25 is the sectional view of the brief configuration on the integrated light guide road of expression sixteenth embodiment of the invention.
Figure 26 is the vertical view of the brief configuration on the integrated light guide road of expression seventeenth embodiment of the invention.
Figure 27 is the sectional view of the brief configuration of first waveguide region 1201 of expression Figure 26.
Figure 28 is the vertical view of the brief configuration on the integrated light guide road of expression eighteenth embodiment of the invention.
Figure 29 is the sectional view of the brief configuration of second waveguide region 1402 of expression Figure 28.
Figure 30 incides under the situation on composition surface of refractive index different material for expression light, the schematic diagram of incidence angle and refraction angle relation.
Figure 31 for expression light in the different material of refractive index under the guided wave situation, with the diagram of the relation of wave guide direction angulation and refractive index ratio.
Figure 32 incides under the situation on composition surface of the different material of refractive index for expression light, incidence angle and with the diagram of the relation of the reflectivity of plane of incidence parallel portion.
Figure 33 is the vertical view of the brief configuration on the integrated light guide road of expression nineteenth embodiment of the invention.
Figure 34 is the vertical view of the brief configuration on the integrated light guide road of expression twentieth embodiment of the invention.
Figure 35 is the vertical view of the brief configuration on the integrated light guide road of expression 21st embodiment of the invention.
Figure 36 is the stereogram of the brief configuration on the integrated light guide road of expression 22nd embodiment of the invention.
Embodiment
Below with reference to figure several embodiments of the present invention is described.At first as first execution mode,, represent several embodiment and describe for the application examples in the semiconductor laser.In this execution mode,, can control the dependence of the vibration wavelength of semiconductor laser to temperature by semiconductor laser is made up the different material of temperature dependence with refractive index.
As second execution mode,, represent several embodiment and describe for the application examples in the integrated light guide road.In this execution mode, when integrated, can reduce the reflection on the boundary face between these optical waveguides to the different optical waveguide of the dependence of temperature to semiconductor light wave guide passage and refractive index and refractive index.By integrated, can realize having the optical waveguide of only using the unavailable new features of semiconductor in addition the semiconductor light wave guide passage optical waveguide different with refractive index.
In addition as the 3rd execution mode, the boundary face of the semiconductor light wave guide passage optical waveguide different with refractive index is configured to tilt with respect to wave guide direction, can reduce the waveguide path loss that reflection between these optical waveguides and refraction cause and lose.By integrated, can realize having the optical waveguide of only using the unavailable new features of semiconductor in addition the semiconductor light wave guide passage optical waveguide different with refractive index.
(application examples in the semiconductor laser)
With reference to figure the semiconductor laser of first execution mode of the present invention is described.Adopt this first execution mode,, can provide the semiconductor laser of may command vibration wavelength temperature dependence the refractive index combination of materials different to the characteristic of temperature.Several specific embodiments to present embodiment describe below.
Fig. 1 is the sectional view along the structure of the semiconductor laser of fiber waveguide direction indication first embodiment of the invention.First embodiment can control the dependence of vibration wavelength to temperature by at the first gain regions R1 that wavelength selectivity is arranged with have the different transmission region R3 that does not have gain of refractive index is set between the second gain regions R2 of wavelength selectivity.
In Fig. 1, semiconductor substrate 101 is provided with the first gain regions R1 transmission region R3 that do not have gain and second gain regions R2 that wavelength selectivity arranged different with refractive index of wavelength selectivity.Wherein in gain regions R1, be provided with the active layer 102 that on semiconductor substrate 101, forms.On active layer 102, form first gain regions electrode 105 by coating layer 110.
In gain regions R2, be provided with the active layer 104 that on semiconductor substrate 101, forms.On active layer 104, form second gain regions electrode 106 by coating layer 110.
As semiconductor substrate 101 and coating layer 110, for example can use InP, as active layer 102,104, for example can use vibration wavelength is the GaInAsP of 1.55 μ m.Wherein the active layer 102 that forms on semiconductor substrate 101 has first gain that wavelength selectivity is arranged, and active layer 104 has second gain that wavelength selectivity is arranged.Form the periodic perturbation of complex refractivity index (a complex refractive index) respectively in active layer 102,104, just form diffraction grating respectively, active layer 102,104 becomes the distribution catoptric arrangement.
This external transmission region R3 is provided with the removal zone 111 that forms with removing active layer 102,104 on a part of semiconductor substrate 101 and coating layer 110, fills the refractive index temperature-compensating material 103 different with gain regions R1 and/or R2 to the dependence of temperature in removing zone 111.
Wherein as temperature-compensating material 103, for example can use to have the organic material of the refractive index opposite with semiconductor to the dependence of temperature, as such organic material, what for example can exemplify has a BCB (Benzocyclobutene, benzocyclobutene).Use the multilayer film of organic material can reduce bend loss as temperature-compensating material 103 in addition.
Forming on the semiconductor substrate 101 under the situation of the transmission region R3 that does not have gain, the anisotropic etching of use reactive ion etching etc., between gain regions R1, R2, form the groove of desired width, can be filled into slot part to organic material with methods such as rotary coating.
This external resonator end faces of both sides forms the first gain regions lateral reflection respectively and prevents that the film 108 and the second gain regions lateral reflection from preventing film 109, forms backplate 107 at semiconductor substrate 101 back sides.
Wherein the length of the first gain regions R1, the second gain regions R2 and transmission region R3 only can be set at and not vibrate with the first gain regions R1 or the second gain regions R2.
Light luminous with the first gain regions R1 that wavelength selectivity is arranged or reflection does not reflect by having the transmission region R3 of gain, use the second gain regions R2 that wavelength selectivity is arranged.The light that is reflected by there not being the transmission region R3 of gain, turns back to the first gain regions R1 of wavelength selectivity once more, can cause the laser vibration.
Therefore in the first gain regions R1, the second gain regions R2 and transmission region R3, can carry out the laser vibration, the variation of the vibration wavelength that the Phase Shift Offset that can cause with the variations in temperature of transmission region R3 is caused by the variations in temperature at the first gain regions R1 and the second gain regions R2.
Organic materials such as use BCB can be controlled the dependence of the vibration wavelength of semiconductor laser to temperature.Therefore do not use new material,, can realize making the vibration wavelength of semiconductor laser stable with simple structure and easy method for processing.
With by being located at the diffraction grating effective length on the active layer 102,104 and not having longitudinal mode spacing (longitudinal mode spacing) that the length sum of the transmission region R3 of gain determines the wide mode of stopband width (stop bandwidth: suppress bandwidth), set the length that not have the transmission region R3 that gains than diffraction grating.1 longitudinal mode is present in the stopband width of diffraction grating, and the gain that can constrain other longitudinal modes can improve the stability of single mode action (single mode operation).
Below with reference to present embodiment vibration principle and vibration wavelength are elaborated.
The first gain regions R1 of wavelength selectivity is arranged and the second gain regions R2 of wavelength selectivity is arranged, can only reflect the light of the wavelength of determining by diffraction grating owing to have wavelength selectivity and optical gain simultaneously, can amplification.The wavelength band territory of wherein reflection maximum can be that the stopband width at center is determined in order to the bragg wavelength of diffraction grating.The coupling coefficient K that for example establishes diffraction grating is 300cm -1,, can obtain being about 10nm as the stopband width by being length setting 50 μ m.There is not the length of the transmission region 103 of gain for example can be set at about 10 μ m in addition.
Fig. 2 is the reflectance spectrum of semiconductor laser of expression one embodiment of the present invention and the diagram of reflected wave phase characteristic, represents the reflectance spectrum of diffraction grating of the first gain regions R1 and the second gain regions R2 and the phase delay of reflected wave.
In Fig. 2, under the situation of the phase delay when the transmission region R3 that does not have gain does not exist or do not have light to pass through transmission region R3, because of the phase delay of the diffraction grating of the first gain regions R1 and the second gain regions R2 and be the integral multiple of 0 or 2 π, just only consider the side's of the first gain regions R1 or the second gain regions R2 words, phase delay is 0 or during π, its wavelength becomes mode of resonance.
Have the transmission region R3 that does not have gain, after light comes out from the first gain regions R1, before entering the second gain regions R2, change phase place.Therefore corresponding to the phase change in transmission region R3, mode of resonance is that the mode of 0 or 2 π changes with the phase delay of the resonator integral body that is made of the first gain regions R1, the second gain regions R2 and transmission region R3 between stopband.
Wherein with the semi-conducting material that is using in the general semiconductor laser of InP and GaAs etc., because the words refractive index that environment temperature raises also increases, the bragg wavelength of diffraction grating is pressed formula (1) to long wavelength's one side shifting.The reflectance spectrum of Fig. 2 is also whole to long wavelength's one side shifting as a result for it.
Temperature-compensating material 103 for example is to have under the situation of the refractive index opposite with semiconductor to the material of the dependence of temperature on the other hand, raises with temperature, and the refractive index of temperature-compensating material 103 reduces, and does not have the optical length of the transmission region R3 of gain to reduce.Therefore the light phase of the transmission region R3 by there not be gain changes, with the temperature rising, vibration wavelength in stopband from long wavelength one side direction central authorities, then to short wavelength's one side shifting.
Therefore be used in the change that phase change that the variations in temperature of transmission region R3 causes can compensate the bragg wavelength that the variations in temperature at the first gain regions R1 and the second gain regions R2 causes, can control the dependence of the vibration wavelength of semiconductor laser temperature.
Fig. 3 for the vibration wavelength of the semiconductor laser of explanation one embodiment of the present invention to the diagram of the compensation principle of temperature dependence.
As can be seen, temperature raises, the bragg wavelengths of diffraction grating in Fig. 3 BShift to long wavelength's one side, even temperature changes, vibration wavelength is also constant.Stopband width SB is wide more in addition, can compensate in wide temperature range more.For example in the example of Fig. 1, the coupling coefficient K that establishes diffraction grating is 300cm -1,, can enlarge the temperature range of compensation with the width of big coupling coefficient expansion stopband.
In the above-described embodiment, having illustrated is not both having wavelength selectivity not have among the transmission region R3 of gain yet, use has the method for the refractive index opposite with semiconductor to the temperature-compensating material 103 of the dependence of temperature, can make of the material of changing transmission region R3 to have the semiconductor laser of temperature dependence arbitrarily.Because the transmission region R3 that not have to gain there is no need luminously, may not have good crystallization property in addition.Therefore can use organic material and other semiconductors material in addition, the selectivity of material is broadened.For example use in addition and have than the material of the big refractive index of the semiconductor of diffraction grating part to the dependence of temperature, also can constitute the transmission region that does not have gain, like this can the big semiconductor laser of formation temperature dependence, can be used as uses such as temperature sensor.Even the material that the Yin Wendu rising refractive index in addition resemble the semiconductor increases by selecting to have than the material of the little refractive index of the semiconductor of diffraction grating part to the dependence of temperature, can reduce the dependence of vibration wavelength to temperature.
Fig. 4 is the thermal refractive index coefficient difference of semiconductor laser of explanation one embodiment of the present invention and the vibration wavelength diagram to temperature dependence.In Fig. 4, transverse axis represents that the gain regions of wavelength selectivity is arranged and had not both had wavelength selectivity also not have the product of difference and the length of the transmission region that had not both had wavelength selectivity also not have to gain of thermal refractive index coefficient of the transmission region of gain that the longitudinal axis is represented the variation of vibration wavelength to the dependence of temperature.Wherein being illustrated in addition only is in the semiconductor structure, uses the example under the situations such as coupling coefficient of each zone length identical with Fig. 1, diffraction grating.
As can be seen, under the situation of Distributed Feedback Laser, vibration wavelength is about 1 /K to the dependence of temperature in Fig. 4.Therefore vibration wavelength is changed under about 10% the situation at it, the product of the difference of the temperature differential coefficient of the temperature differential coefficient of the effective refractive index of gain regions R1, R2 and the effective refractive index of transmission region R3 and the length of transmission region R3 can be A point (minimizing) or A ' point (increase), and this value is for ± 7.5 * 10 -4[μ m/K].This is external to change under about 20% the situation vibration wavelength, and the product of the difference of the temperature differential coefficient of the temperature differential coefficient of the effective refractive index of gain regions R1, R2 and the effective refractive index of transmission region R3 and the length of transmission region R3 is ± 14.5 * 10 -4[μ m/K] just can.When for example the length of transmission region R3 is 10 μ m, be respectively ± 7.5 * 10 -4[1/K], ± 1.45 * 10 -4[1/K].
Structure about the active layer 102,104 of Fig. 1 is not provided with special restriction in addition, by the active layer of general all structures commonly used is used for the present invention, can control the dependence of the vibration wavelength of semiconductor laser to temperature.Just can be suitable for for any materials such as InGaAsP, GaAs, AlGaAs, InGaAs, GaInNAs about active layer 102,104,, also can use about the waveguide line structure in active layer zone in addition and imbed pn, ridge structure, semi-insulating structure, Gao Tai (high-mesa) structure etc. imbedded no matter be that main body, MQW (multiple quantum trap), quantum wire, quantum dot can be suitable for about the structure of active layer 102,104.About semiconductor substrate 101 is not to be defined in n type substrate yet, can use p type substrate, semi-insulating type substrate etc. yet.
Even periodic perturbation does not directly form on active layer 102,104 in addition, if the electric field of the light of active layer waveguide be not zero but zone with finite value form, can expect has same effect.Form on the sch layer of the separation limitation structure (separate confinement heterostructure) (SCH structure) that for example can in general semiconductor laser, use, also can coat the layer of floor height in addition at the folded refractive index ratio of the area level of not joining with active layer, form periodic perturbation thereon.
In addition by make at least the transmission region that does not have gain up and down or about some waveguide line structures with light limitation structure (optical confinement structure), can reduce transmission loss, the characteristic of semiconductor laser is improved.
Form structure of the present invention on the thickness direction of this external substrate, can expect also that as the surface light emitting laser type same effect is arranged.The first gain regions R1, transmission region R3 and the second gain regions R2 are arranged again along optical axis words side by side, can be by speculum with making such as etchings, dispose the first gain regions R1, transmission region R3 and the second gain regions R2, also can make optical axis direction floor direction or transverse direction bending midway on the waveguide road.
Fig. 5 is the sectional view along the structure of the semiconductor laser of fiber waveguide direction indication second embodiment of the invention.Second embodiment be by the gain regions R11 that the wavelength selection type is arranged and do not have the gain reflector space R12 between, the refractive index transmission region R13 that do not have gain different to the dependence of temperature is set, makes the semiconductor laser of control vibration wavelength the dependence of temperature.
In Fig. 5, semiconductor substrate 201 is provided with gain regions R11 with wavelength selectivity, refractive index to the different transmission region R13 that does not have gain of the dependence of temperature with the reflector space R12 that gains of not have of wavelength selectivity is arranged.Wherein be arranged on formation on the semiconductor substrate 201 on the gain regions R11, having wavelength selectivity that the active layer 202 of gain is arranged.Form the periodic perturbation of complex refractivity index on active layer 202, just form diffraction grating, active layer 202 is the distribution catoptric arrangement.On active layer 202, form electrode 205 by coating layer 210.
Be arranged on this external reflector space R12 on the semiconductor substrate 201 form, have wavelength selectivity and not have the semiconductor layer 204 that gains.Wherein form the periodic perturbation of complex refractivity index on semiconductor layer 204, just form diffraction grating, semiconductor layer 204 becomes the distribution catoptric arrangement.On semiconductor layer 204, form coating layer 210.As semiconductor substrate 201 and coating layer 210, for example can use InP, as active layer 202, for example using emission wavelength is the GaInAsP of 1.55 μ m, as semiconductor layer 204, for example using emission wavelength is the GaInAsP of 1.2 μ m.By selective growth make with the growth of the material of active layer 202 different compositions after, can form semiconductor layer 204 by the diffraction grating that makes periodic structure.
The removal zone 211 of the part formation of removing active layer 202, semiconductor layer 204 and coating layer 210 on the semiconductor substrate 201 is set on this external transmission region R13, is removing the filling refractive index temperature-compensating material 203 different with gain regions R11 on the zone 211 with reflector space R12 to the dependence of temperature.
Wherein as temperature-compensating material 203, for example can use to have the refractive index organic material opposite with semiconductor to temperature dependence, as such organic material, what for example can exemplify has a BCB.As temperature-compensating material 203, use the multilayer film of organic material can reduce bend loss in addition.
Forming on the semiconductor substrate 201 under the situation of the transmission region R13 that does not have gain, the anisotropic etching of use reactive ion etching etc., between gain regions R11, R12, form the groove of desired width, can fill organic material at slot part with methods such as rotary coating.
This external resonator end faces of both sides forms the gain regions lateral reflection and prevents that film 208 and reflector space lateral reflection from preventing film 209, forms backplate 207 at semiconductor substrate 201 back sides.Wherein can be only not produce the length of the mode of vibration setting gain regions R11 of big reflection loss with gain regions R11.
Light luminous at the gain regions R11 that wavelength selectivity is arranged or reflection passes through not have the transmission region R13 of gain, there is not the reflector space R12 of gain to reflect with having wavelength selectivity, again by there not being the transmission region R13 of gain, turn back to the gain regions R11 of wavelength selectivity, produce feedback, can evoke the laser vibration.
Therefore can make the vibration of gain regions R11, reflector space R12 and transmission region R13 participation laser, the variation of the vibration wavelength that Phase Shift Offset gain regions R11 that can cause with the variations in temperature of transmission region R13 and the variations in temperature of reflector space R12 cause.
The organic material of use BCB etc. can be controlled the dependence of the vibration wavelength of semiconductor laser to temperature.Therefore do not use new material,, can realize making the stablizing of vibration wavelength of semiconductor laser with simple structure and method for processing easily.
With by being located at the diffraction grating effective length on active layer 202 and the semiconductor layer 204 respectively and not having longitudinal mode spacing (longitudinalmode spacing) that the length sum of the transmission region R13 of gain determines, set the length that not have the transmission region R13 that gains than the wide mode of the stopband width of diffraction grating.1 longitudinal mode is present in the stopband width of diffraction grating, and the gain that can constrain other longitudinal modes can improve the stability of single mode action.
In the above-described embodiment, to being illustrated in the method that does not both have wavelength selectivity also not have the transmission region R13 of gain to use to have the refractive index opposite to the temperature-compensating material 203 of the dependence of temperature with semiconductor, the material of transmission region R13 is changed in utilization, can make to have any semiconductor laser to temperature dependence.Because the transmission region R13 that not have to gain there is no need luminously, do not need to have good crystallization property in addition.Therefore can use organic material and other semiconductors material in addition, the selectivity of material is broadened.For example use in addition and have than the material of the big refractive index of the semiconductor of diffraction grating part to the dependence of temperature, also can constitute the transmission region that does not have gain, like this can the big semiconductor laser of formation temperature dependence, can be used as uses such as temperature sensor.Even the material that the Yin Wendu rising refractive index in addition resemble the semiconductor increases by selecting to have than the material of the little refractive index of the semiconductor of diffraction grating part to the dependence of temperature, can reduce the dependence of vibration wavelength to temperature.
Structure about the active layer 202 of Fig. 5 is not provided with special restriction in addition, by the active layer of general all structures commonly used is used for the present invention, can control the dependence of the vibration wavelength of semiconductor laser to temperature.Just can be suitable for for any materials such as InGaAsP, GaAs, AlGaAs, InGaAs, GaInNAs about active layer 202,, also can use about the waveguide line structure in active layer zone in addition and imbed pn, ridge structure, semi-insulating structure, Gao Tai (high-mesa) structure etc. imbedded no matter be that main body, MQW (multiple quantum trap), quantum wire, quantum dot can be suitable for about the structure of active layer 202.Also be not limited to n type substrate about semiconductor substrate 201, also can use p type substrate, semi-insulating type substrate etc.
Even periodic perturbation does not directly form on active layer 202 in addition, if be the electric field of the light of active layer waveguide be not zero but zone with finite value form, can expect has same effect.Form on the sch layer of the separation that for example can in general semiconductor laser, use limitation structure (SCH structure), also can coat the layer of floor height in addition, form periodic perturbation thereon at the folded refractive index ratio of area level that does not join with active layer.
In addition by make the transmission region that does not have gain up and down or about the waveguide line structure of at least one side with light limitation structure, can reduce transmission loss, the characteristic of semiconductor laser is improved.
Form structure of the present invention on the thickness direction of this external substrate, can expect also that as the surface light emitting laser type same effect is arranged.The words that have gain regions R11, transmission region R13 and reflector space R12 to arrange again along optical axis, can be by speculum with making such as etchings, configuration gain regions R11, transmission region R13 and reflector space R12 also can make optical axis direction floor direction or transverse direction bending on the waveguide road midway.
Fig. 6 is the sectional view along the structure of the semiconductor laser of fiber waveguide direction indication third embodiment of the invention.This 3rd embodiment is by refractive index being coupling on the gain regions R21 of wavelength selectivity the different transmission region R22 that does not have gain of the dependence of temperature, controlling the embodiment of vibration wavelength to the dependence of temperature.
In Fig. 6, the gain regions R21 transmission region R22 that do not have gain different to the dependence of temperature with refractive index with wavelength selectivity is set on semiconductor substrate 301.Wherein gain regions R21 be provided with on semiconductor substrate 301 form, have wavelength selectivity that the active layer 302 of gain is arranged.Form the periodic perturbation of complex refractivity index on active layer 302, just form diffraction grating, active layer 302 is the distribution catoptric arrangement.On active layer 302, form electrode 305 by coating layer 310.As semiconductor substrate 301 and coating layer 310, for example can use InP, as active layer 302, for example using emission wavelength is the GaInAsP of 1.55 μ m.
The refractive index temperature-compensating material 303 different with gain regions R21 to the dependence of temperature filled removing in the removal zone 312 that the part of the active layer 302 removed on the semiconductor substrate 301 and coating layer 310 is set on this external transmission region R22 and forms on the zone 312.
Wherein as temperature-compensating material 303, for example can use to have the refractive index organic material different with semiconductor to the dependence of temperature, as such organic material, what for example can exemplify has a BCB.Use the multilayer film of organic material can reduce bend loss as temperature-compensating material 303 in addition.
Forming on the semiconductor substrate 301 under the situation of the transmission region R22 that does not have gain, the anisotropic etching of use reactive ion etching etc., form the groove of desired width in gain regions R21 end, can be filled into slot part to organic material with methods such as rotary coating.
The end face of the gain regions R21 of this external resonator with respect to the cleavage surface of the semiconductor substrate 301 that forms active layer 302, forms antireflection film 308.The end face of the transmission region R22 side of this external resonator forms highly reflecting films 311.Form backplate 307 at semiconductor substrate 301 back sides.Wherein can set the length of gain regions R21 only not produce the mode of vibration of big reflection loss with gain regions R21.
Light luminous at the gain regions R21 that wavelength selectivity is arranged or reflection passes through not have the transmission region R22 of gain, with highly reflecting films 311 reflections, by there not being the transmission region R22 of gain, turn back to the gain regions R21 of wavelength selectivity again, produce feedback, can evoke the laser vibration.
Therefore can make gain regions R21 and transmission region R22 have influence on the vibration of laser, the variation of the vibration wavelength that the variations in temperature of the Phase Shift Offset gain regions R21 that can cause with the variations in temperature of transmission region R22 causes.
The organic material of use BCB etc. can be controlled the dependence of the vibration wavelength of semiconductor laser to temperature.Therefore do not use new material,, can realize making the stable of semiconductor laser vibration wavelength with simple structure and easy method for processing.
In the longitudinal mode spacing mode of determining by the length sum of the transmission region R22 that is located at the diffraction grating effective length on the active layer 202 and does not have to gain wideer, set the length of the transmission region R22 that does not have gain than the stopband width of diffraction grating.1 longitudinal mode is present in the stopband width of diffraction grating, and the gain that can constrain other longitudinal modes can improve the stability of single mode action.
In the above-described embodiment, to both there not being wavelength selectivity not have among the transmission region R22 of gain yet, use has the refractive index opposite with semiconductor the method for the temperature-compensating material 303 of the dependence of temperature is illustrated, and utilizes the material of changing transmission region R22 to make to have arbitrarily the semiconductor laser to temperature dependence.Because the transmission region R22 that not have to gain there is no need luminously, do not need to have good crystallization property in addition.Therefore can use organic material and other semiconductors material in addition, the selectivity of material is broadened.For example use in addition and have than the material of the big refractive index of the semiconductor of diffraction grating part to the dependence of temperature, also can constitute the transmission region that does not have gain, like this can the big semiconductor laser of formation temperature dependence, can be used as uses such as temperature sensor.Even the material that the Yin Wendu rising refractive index in addition resemble the semiconductor increases by selecting to have than the material of the little refractive index of the semiconductor of diffraction grating part to the dependence of temperature, can reduce the dependence of vibration wavelength to temperature.
Structure about the active layer 302 of Fig. 6 is not provided with special restriction in addition, by the active layer of general all structures commonly used is used for the present invention, can control the dependence of the vibration wavelength of semiconductor laser to temperature.Just can be suitable for for any materials such as InGaAsP, GaAs, AlGaAs, InGaAs, GaInNAs about active layer 302,, also can use about the waveguide line structure in active layer zone in addition and imbed pn, ridge structure, semi-insulating structure, the high platform structure etc. imbedded no matter be that main body, MQW (multiple quantum trap), quantum wire, quantum dot can be suitable for about the structure of active layer 302.About semiconductor substrate 301 is not to be defined in n type substrate yet, can use p type substrate, semi-insulating type substrate etc. yet.
Even periodic perturbation does not directly form on active layer 302 in addition, if be the electric field of the light of active layer waveguide be not zero but zone with finite value form, can expect has same effect.Form on the sch layer of the separation that for example can in general semiconductor laser, use limitation structure (SCH structure), also can coat the layer of floor height in addition, on it, form periodic perturbation at the folded refractive index ratio of area level that does not join with active layer.
In addition by make the transmission region that does not have gain up and down or about the waveguide line structure of at least one side with light limitation structure, can reduce transmission loss, the characteristic of semiconductor laser is improved.
Form structure of the present invention on the thickness direction of this external substrate, can expect also that as the surface light emitting laser type same effect is arranged.There are gain regions R21 and transmission region R22 to arrange again along optical axis, can be by speculum with making such as etchings, configuration gain regions R21 and transmission region R22 also can make optical axis direction floor direction or transverse direction bending on the waveguide road midway.
Fig. 7 is the sectional view along the structure of the semiconductor laser of fiber waveguide direction indication fourth embodiment of the invention.This 4th embodiment is that the control vibration wavelength is to the embodiment of the dependence of temperature by the stacked transmission region R32 that does not have gain on the surface-emitting type laser.
In Fig. 7, on semiconductor substrate 401, be laminated with the gain regions R31 of wavelength selectivity.Be laminated with the refractive index transmission region R32 that do not have gain different on this external gain regions R31, on transmission region R32, be provided with the refractive index temperature-compensating material 404 different with gain regions R31 the dependence of temperature to the dependence of temperature.Wherein on gain regions R31, be provided with the distributed Bragg reflecting layer 402 that is laminated on the semiconductor substrate 401 and be layered in active region 403 on the distributed Bragg reflecting layer 402, that wavelength selectivity is arranged.Distributed Bragg reflecting layer 402 has forms different semiconductor layer 409a, 409b alternately laminated structure mutually, and active region 403 can have active layer 408a and the mutual alternately laminated structure of coating layer 408b.On active region 403, form the electrode 405 that is provided with the peristome 406 that makes the light ejaculation.Gain regions R31 also can not everyly have gain, as long as obtain gaining just passable as the integral body of gain regions R31.
As semiconductor substrate 401, for example can use InP, as active layer active layer 408a and coating layer 408b, for example can use GaInAs/InAlAs, as semiconductor layer 409a, 409b, can use InAlGaAs/InAlAs.
Wherein, for example can use to have the organic material of the refractive index different, as such organic material example, as the BCB that has that can exemplify to temperature dependence with semiconductor as temperature-compensating material 404.As temperature-compensating material 404, use the multilayer film of organic material can reduce bend loss in addition.Can form the transmission region R32 that does not have gain by coating on gain regions R31 or accumulation organic material etc. in addition.
Form highly reflecting films 411 on this external temperature-compensating material 404, form backplate 407 at semiconductor substrate 401 back sides.Wherein can set the active layer 408a of active region 403 and each number of plies of coating layer 408b only not produce the mode of vibration of big reflection loss with it.
Light luminous at the gain regions R31 that wavelength selectivity is arranged or reflection passes through not have the transmission region R32 of gain, with highly reflecting films 411 reflections, by there not being the transmission region R32 of gain, turn back to the gain regions R31 of wavelength selectivity again, produce feedback, can evoke the laser vibration.
Therefore can make gain regions R31 and transmission region R32 be related to the vibration of laser, the variation of the vibration wavelength that the variations in temperature of the Phase Shift Offset gain regions R31 that can cause with the variations in temperature of transmission region R32 causes.
The organic material of use BCB etc. can be controlled the dependence of the vibration wavelength of semiconductor laser to temperature.Therefore do not use new material,, can realize making the stable of semiconductor laser vibration wavelength with simple structure and easy method for processing.
With by the effective length of the diffraction grating of gain regions R31 and the longitudinal mode spacing mode wideer that do not have the length sum of the transmission region R32 of gain to determine, set the thickness that not have the transmission region R32 that gains than the stopband width of diffraction grating.1 longitudinal mode is present in the stopband width of diffraction grating, and the gain that can constrain other longitudinal modes can improve the stability of single mode action.
In the above-described embodiment, to be illustrated, utilize the material of changing transmission region R32 to make the semiconductor laser that has arbitrarily temperature dependence in the method that does not both have wavelength selectivity also not have the transmission region R32 of gain to use to have the refractive index opposite to the temperature-compensating material 404 of the dependence of temperature with semiconductor.Because the transmission region R32 that not have to gain there is no need luminously, do not need to have good crystallization property in addition.Therefore can use organic material and other semiconductor material in addition, the selectivity of material is broadened.For example use in addition and have than the material of the big refractive index of the semiconductor of diffraction grating part to the dependence of temperature, also can constitute the transmission region that does not have gain, like this can the big semiconductor laser of formation temperature dependence, can be used as uses such as temperature sensor.Even the material that the Yin Wendu rising refractive index in addition resemble the semiconductor increases by selecting to have than the material of the little refractive index of the semiconductor of diffraction grating part to the dependence of temperature, can reduce the dependence of vibration wavelength to temperature.
Structure about the active region 403 of Fig. 7 is not provided with special restriction in addition, by the active region 403 of general all structures commonly used is used for the present invention, can control the dependence of the vibration wavelength of semiconductor laser to temperature.Just can be suitable for for any materials such as InGaAsP, GaAs, AlGaAs, InGaAs, GaInNAs about active region 403,, also can use about the waveguide line structure of active region in addition and imbed pn, semi-insulating structure, the oxidation narrow structures etc. imbedded no matter be that main body, MQW (multiple quantum trap), quantum wire, quantum dot can be suitable for about the structure of active region 403.About semiconductor substrate 401 is not to be defined in n type substrate yet, can use p type substrate, semi-insulating type substrate etc. yet.
By the transmission region that does not have gain being made certain waveguide line structure of light limitation structure, can reduce transmission loss in addition, the characteristic of semiconductor laser is improved.
Fig. 8 is the sectional view along the structure of the semiconductor laser of fiber waveguide direction indication fifth embodiment of the invention.This 5th embodiment combines to the different transmission region R42 that does not have gain of the dependence of temperature refractive index by the light chopper structure with the gain regions R41 coupling that wavelength selectivity is arranged, the control vibration wavelength is to the embodiment of the dependence of temperature.
In Fig. 8, the transmission region R42 that has gain regions R41, the speculum 512 of wavelength selectivity and do not have gain is set on semiconductor substrate 501.Gain regions R41 and transmission region R42 carry out optical coupled by speculum 512.Wherein gain regions R41 be provided with on semiconductor substrate 501 form, have wavelength selectivity that the active layer 502 of gain is arranged.Form the periodic perturbation of complex refractivity index on active layer 502, just form diffraction grating, active layer 502 is the distribution catoptric arrangement.On active layer 502, form electrode 505 by coating layer 510.As semiconductor substrate 501 and coating layer 510, for example can use InP, as active layer 502, for example can use emission wavelength is the GaInAsP of 1.55 μ m.To be configured in the mode of gain regions R41 one end, speculum 512 is set on this external semiconductor substrate 501.Wherein, on coating layer 510, form the mode on the inclined planes of spending with vertical direction inclination 90, make speculum 512 by the coating layer 510 of etching gain regions R41 end.
The refractive index temperature-compensating material 503 different with gain regions R41 to the dependence of temperature is set on this external transmission region R42, and temperature-compensating material 503 is configured on the coating layer 510 by in the mode towards speculum 512.There is not the transmission region R42 of gain to constitute by light path and the temperature-compensating material 503 before arriving temperature-compensating material 503 by reflecting with speculum 512 at the light that penetrates from gain regions R41
Wherein as temperature-compensating material 503, for example can use to have the organic material of the refractive index different with semiconductor to temperature dependence, as such organic material, what for example can exemplify has a BCB.As temperature-compensating material 503, use the multilayer film of organic material can reduce bend loss in addition.
Forming on the coating layer 510 under the situation of the transmission region R42 that does not have gain, making of coating of methods such as rotary coating or accumulation organic material.
Form highly reflecting films 511 on this external temperature-compensating material 503, at the end face of the gain regions R41 of resonator, the cleavage surface to the semiconductor substrate 501 that is formed with active layer 502 forms antireflection film 508.Form backplate 507 at semiconductor substrate 501 back sides.Wherein can be only not produce the length of the mode of vibration setting gain regions R41 of big reflection loss with gain regions R41.
Luminous at the gain regions R41 that wavelength selectivity is arranged or reflect light is folded to direction through speculum 512 optical axises, by there not being the transmission region R42 of gain, with highly reflecting films 511 reflections.Again by there not be the transmission region R42 of gain, make optical axis bend towards horizontal direction with the light of highly reflecting films 511 reflection, turn back to the gain regions R41 of wavelength selectivity, produce and feed back, can evoke laser and vibrate with speculum 512.
Therefore can make gain regions R41 and transmission region R42 have influence on the vibration of laser, the variation of the vibration wavelength that the variations in temperature of the Phase Shift Offset gain regions R41 that can cause with the variations in temperature of transmission region R42 causes.
The organic material of use BCB etc. can be controlled the dependence of the vibration wavelength of semiconductor laser to temperature.Therefore do not use new material,, can realize making the stable of semiconductor laser vibration wavelength with simple structure and easy method for processing.
In the longitudinal mode spacing mode of determining by the length sum of the transmission region R42 that is located at the diffraction grating effective length on the active layer 502 and does not have to gain wideer, set the length of the transmission region R42 that does not have gain than the stopband width of diffraction grating.1 longitudinal mode is present in the stopband width of diffraction grating, and the gain that can constrain other longitudinal modes can improve the stability of single mode action.
In the above-described embodiment, use speculum, for example also can utilize diffraction grating etc. to carry out light chopper, can expect to obtain same effect as the light chopper structure.In addition in the above-described embodiment, the mode of carrying out conversion with level and optical axis up and down forms speculum, but also can carry out the optical axis conversion for example in same horizontal plane internal reflection, and it is one that reflection position also there is no need.Have the refractive index opposite the method for the temperature-compensating material 503 of the dependence of temperature is illustrated in both not compensating selectivity and also do not have the transmission region R42 of gain, using in addition, can make of the material of replacing transmission region R42 and have the semiconductor laser of temperature dependence arbitrarily with semiconductor.Because the transmission region R42 that not have to gain there is no need luminously, may not have good crystallization property in addition.Therefore can use organic material and other semiconductors material in addition, the selectivity of material is broadened.For example use in addition and have than the material of the big refractive index of the semiconductor of diffraction grating part to the dependence of temperature, also can constitute the transmission region that does not have gain, like this can the big semiconductor laser of formation temperature dependence, can be used as uses such as temperature sensor.Even the material that the Yin Wendu rising refractive index in addition resemble the semiconductor increases by selecting to have than the material of the little refractive index of the semiconductor of diffraction grating part to the dependence of temperature, can reduce the dependence of vibration wavelength to temperature.
Structure about the active layer 502 of Fig. 8 is not provided with special restriction in addition, by the active layer of general all structures commonly used is used for the present invention, can control the dependence of the vibration wavelength of semiconductor laser to temperature.Just can be suitable for for any materials such as InGaAsP, GaAs, AlGaAs, InGaAs, GaInNAs about active layer 502,, also can use about the waveguide line structure in active layer zone in addition and imbed pn, ridge structure, semi-insulating structure, the high platform structure etc. imbedded no matter be that main body, MQW (multiple quantum trap), quantum wire, quantum dot can be suitable for about the structure of active layer 502.About semiconductor substrate 501 is not to be defined in n type substrate yet, can use p type substrate, semi-insulating type substrate etc. yet.
Even periodic perturbation does not directly form on active layer 502 in addition, if be the electric field of the light of active layer waveguide be not zero but zone with finite value form, can expect has same effect.For example can be in general semiconductor laser form on the sch layer of employed separation limitation structure (SCH structure), also can coat the layer of floor height in addition, form periodic perturbation thereon at the folded refractive index ratio of area level that does not join with active layer.
By the transmission region that does not have gain being made certain waveguide line structure of light limitation structure, can reduce transmission loss in addition, the characteristic of semiconductor laser is improved.
Fig. 9 is illustrated in the sectional view of structure that cuts off the semiconductor laser of sixth embodiment of the invention perpendicular to the fiber waveguide direction.This 6th embodiment is by the optical transmission zone gain regions different with structure being set, controlling the embodiment of vibration wavelength to the dependence of temperature.
In Fig. 9 A, sequential cascade resilient coating 602, light limitation layer 603, core layer 604, light limitation layer 605 and cap rock 606 are imbedded these layers with embedding layer 607 on semiconductor substrate 601.
In Fig. 9 B, sequential cascade resilient coating 612, light limitation layer 613, core layer 614, light limitation layer 615 and cap rock 616 are imbedded these layers with embedding layer 617 on semiconductor substrate 611.
In Fig. 9 C, sequential cascade resilient coating 622, light limitation layer 623, core layer 624, light limitation layer 625 and cap rock 626 are imbedded these layers with embedding layer 627 on semiconductor substrate 621.
In Fig. 9 D, sequential cascade resilient coating 632, light limitation layer 633, core layer 634 and cap rock 636 are imbedded these layers with embedding layer 637 on semiconductor substrate 631.
In Fig. 9 E, sequential cascade resilient coating 642, light limitation layer 643, core layer 644, light limitation layer 645 and cap rock 646 are imbedded these layers with organic materials such as BCB 647 on semiconductor substrate 641.
Wherein the thickness of the core layer 614 of Fig. 9 B is than the thin thickness of the core layer 604 of Fig. 9 A.Optical field distribution F1, the F11 of horizontal direction are changed, optical field distribution F2, the F12 of vertical direction are changed, can make each layer different with it the contribution of the dependence of temperature to effective refractive index.Its result can change effective refractive index and its dependence to temperature with the structure of Fig. 9 A and the structure of Fig. 9 B, utilizes the structure of Fig. 9 A and the structure of Fig. 9 B to make up, and can control the dependence of the vibration wavelength of semiconductor laser to temperature.
The width of core layer 624 among Fig. 9 C and light limitation layer 623,625 is narrower than the width of core layer among Fig. 9 B 614 and light limitation layer 613,615.Optical field distribution F12, the F22 of vertical direction are changed, optical field distribution F11, the F21 of horizontal direction are changed, can make each layer different with it the contribution of the dependence of temperature to effective refractive index.Its result can change effective refractive index and its dependence to temperature with the structure of Fig. 9 B and the structure of Fig. 9 C, utilizes the structure of Fig. 9 B and the structure of Fig. 9 C to make up, and can control the dependence of the vibration wavelength of semiconductor laser to temperature.
The structure of Fig. 9 D is compared with the structure of Fig. 9 B, has omitted the upper strata light limitation layer 635 of core layer 633.Optical field distribution F11, the F31 of horizontal direction are changed, optical field distribution F12, the F32 of vertical direction are changed, can make each layer different with it the contribution of the dependence of temperature to effective refractive index.Its result can change effective refractive index and its dependence to temperature with the structure of Fig. 9 B and the structure of Fig. 9 D, utilizes the structure of Fig. 9 B and the structure of Fig. 9 D to make up, and can control the dependence of the vibration wavelength of semiconductor laser to temperature.
In the structure of Fig. 9 E, use organic material 647 to replace the embedding layer 627 of Fig. 9 C.Optical field distribution F22, the F42 of vertical direction are changed, optical field distribution F21, the F41 of horizontal direction are changed, can make each layer different with it the contribution of the dependence of temperature to effective refractive index.Its result can change effective refractive index and its dependence to temperature with the structure of Fig. 9 C and the structure of Fig. 9 E, utilizes the structure of Fig. 9 C and the structure of Fig. 9 E to make up, and can control the dependence of the vibration wavelength of semiconductor laser to temperature.
Like this by Fig. 9 A～Fig. 9 E structure is carried out certain combination, can optical field distribution be changed along the optical waveguide direction, promptly use identical materials to constitute under the situation of semiconductor laser, also can control the dependence of the vibration wavelength of semiconductor laser temperature.
As semiconductor substrate 601,611,621,631,641, resilient coating 602,612,622,632,642, cap rock 606,616,626,636,646 and embedding layer 607,617,627,637, for example can use InP, as core layer 604,614,624,634,644, for example can use emission wavelength is the GaInAsP of 1.3 μ m, as light limitation layer 603,613,623,633,643,605,615,625,645, for example can use emission wavelength is the GaInAsP of 1.1 μ m.
As described above described, if adopt first execution mode of the present invention, use the refractive index material different with gain regions,, can control to the vibration wavelength of semiconductor laser to the dependence of temperature the value of requirement with simpler structure and easy processing to the dependence of temperature.Particularly conduct does not have the material of the transmission region of gain, have the material of the refractive index opposite by use to the dependence of temperature with semiconductor, vibration wavelength is disappeared to the dependence of temperature, can realize that vibration wavelength and temperature do not have the semiconductor laser of dependence.
(the application example in the integrated light guide road)
Below with reference to figure the integrated light guide road of second execution mode of the present invention is described.Adopt this second execution mode, can provide by the semiconductor light wave guide passage with by the refractive index integrated morphology of the optical waveguide that constitutes of the different material of semiconductor light wave guide passage therewith, and provide optical semiconductor photoreactive semiconductor integrated circuit with it.Particularly use present embodiment, can reduce the reflection on the joint interface of the different material of refractive index.Several specific embodiments to present embodiment describe below.
Figure 10 is the stereogram of the coupling part brief configuration on the integrated light guide road of expression seventh embodiment of the invention.This 7th embodiment is by 1 couple of slot part A61 and semiconductor board B61 being set, reducing the embodiment of the borderline reflection of optical waveguide region R 61 and optical waveguide region R 62.
In Figure 10, form optical waveguide region R 61, slot part A61, semiconductor board B61 and optical waveguide region R 62 in proper order in semiconductor substrate 701 upper edge fiber waveguide directions.Wherein can to set refractive index for different mutually for optical waveguide region R 61 and optical waveguide region R 62, and for example optical waveguide region R 61 can constitute with semi-conducting material, and optical waveguide region R 62 can constitute with the material beyond the semiconductor.
Material beyond can filling semiconductor among this external slot part A61 for example can be filled the material identical materials with optical waveguide region R 62.Semiconductor board B61 can constitute in the mode identical with the structure of optical waveguide region R 61 in addition.Slot part A61 and semiconductor board B61 are configured to cross the fiber waveguide direction in addition, and hope can be configured to slot part A61 and semiconductor board B61 vertical with the fiber waveguide direction.
The thickness of the width of slot part A61 and semiconductor board B61 can be set at the light of the boundary reflection of optical waveguide region R 61 and slot part A61 because of at the light of the boundary reflection of slot part A61 and semiconductor board B61, weaken at the light of the boundary reflection of semiconductor board B61 and optical waveguide region R 62.
Even like this optical waveguide beyond semiconductor light wave guide passage and the semiconductor is integrated under the situation on the same semiconductor substrate 701, can reduce the reflection between these optical waveguides, can in the degree of freedom that keeps the design of waveguide road, can realize having the optical waveguide of only using the unavailable new features of semiconductor.
By the semiconductor substrate 701 that forms optical waveguide region R 61 is carried out etching and processing, can on semiconductor substrate 701, form slot part A61 and semiconductor board B61 in addition.Therefore do not form antireflection film, can reduce reflection, can easily handle the integrated of optical waveguide on the border of optical waveguide region R 61 and optical waveguide region R 62 at the interface of optical waveguide region R 61 and optical waveguide region R 62.
Be used in 1 block semiconductor plate B61 is set on the semiconductor substrate 701, can reduce reflection on the border of optical waveguide region R 61 and optical waveguide region R 62, there is no need to resemble and dispose the polylith semiconductor board the distributed reflectors, can make the making on integrated light guide road easy.
Figure 11 is the sectional view along the XI-XI line cut-out of the fiber waveguide direction of Figure 10.In Figure 11, stacked core layer 702a, 702b on semiconductor substrate 701, difference stacked top coating layer 703a, 703b on core layer 702a, 702b.As semiconductor substrate 701 and top coating layer 703a, 703b, for example can use InP, as core layer 702a, 702b, for example can use emission wavelength is the GaInAsP of 1.3 μ m.
This external core layer 702a, 702b and top coating layer 703a, 703b sequential cascade under the situation on the semiconductor substrate 701, molecular beam epitaxial growth), MOCVD (metal organic chemical vaperdepiosition: metal organic chemical vapor deposition) or ALCVD (atomic layer chemicalvaper depiosition: etc. epitaxial growth atomic layer chemical vapour deposition) for example can use MBE (molecular beamepitaxy:.
Carry out etching and processing by the semiconductor substrate 701 that sequential cascade is had core layer 702a, 702b and top coating layer 703a, 703b, form the width d of relative fiber waveguide direction arranged perpendicular 1Groove 704a, form with groove 704a simultaneously and only separate predetermined distance d at semiconductor substrate 701 2The step 704b of configuration.
By in groove 704a, imbedding packing material 705a, simultaneously optical waveguide material 705b is imbedded step 704b, can form the slot part A61 on the interface that is configured in optical waveguide region R 61, the while can form with slot part A61 and separate thickness d 2The optical waveguide region R 62 of semiconductor board B61 configuration.
Can adjust the phase place of the borderline reflected wave of optical waveguide region R 61 and optical waveguide region R 62 like this, can make at the borderline reflected wave of optical waveguide region R 61 and optical waveguide region R 62 and cancel out each other.
Therefore can reduce the borderline reflection of optical waveguide region R 61 and optical waveguide region R 62, can make simultaneously refractive index different mutually optical waveguide region R 61 and optical waveguide region R 62 integrated on same semiconductor substrate 701, can realize having the optical waveguide of only using the unavailable new features of semiconductor.
Wherein as packing material 705a and optical waveguide material 705b, can use the refractive index material different with semiconductor, what for example can exemplify has a BCB (Benzocyclobutene).In this case, the refractive index of equal value that can adopt optical waveguide region R 61 and semiconductor board B61 is 3.12, and the refractive index of equal value of optical waveguide region R 62 and slot part A61 is 1.54.So-called refractive index of equal value is the refractive index with respect to the light definition of propagating in optical waveguide.Therefore under the situation of handling the light of in optical waveguide, propagating, refractive index till now can be replaced as refractive index of equal value.
Bend loss in slot part A61 and optical waveguide region R 62 is little of negligible degree under the short situation of their propagation distances, but the propagation distance in slot part A61 and optical waveguide region R 62 is long, and bend loss can not be ignored.
Therefore the cross section structure of the Figure 11 that cuts off at the XII-XII of Figure 10 line can be replaced as the cross section structure of Figure 12.
Figure 12 is the sectional view along the coupling part brief configuration on the integrated light guide road of fiber waveguide direction indication eighth embodiment of the invention.The embodiment of core layer is set on slot part A61 that this 8th embodiment is Figure 11 and the optical waveguide region R 62.In Figure 12, be formed with optical waveguide region R 71, slot part A71, semiconductor board B71 and optical waveguide region R 72 in proper order in semiconductor substrate 801 upper edge fiber waveguide directions.
Just stacked core layer 802a, 802b on semiconductor substrate 801 distinguish stacked top coating layer 803a, 803b on core layer 802a, 802b.As semiconductor substrate 801 and top coating layer 803a, 803b, for example can use InP, as core layer 802a, 802b, for example can use emission wavelength is the GaInAsP of 1.3 μ m.
Carry out etching and processing by the semiconductor substrate 801 that sequential cascade is had core layer 802a, 802b and top coating layer 803a, 803b, form the groove 804a of relative fiber waveguide direction arranged perpendicular, on semiconductor substrate 801, form the step 804b that only separates the predetermined distance configuration with groove 804a simultaneously.
By the core layer 806a that clamps with coating layer 805a, 807a is imbedded groove 804a, simultaneously the core layer 806b that clamps with coating layer 805b, 807b is imbedded step 804b, the slot part A71 that is configured in the interface of optical waveguide region R 71 can be formed, and the optical waveguide region R 72 that separates semiconductor board B71 configuration with slot part A71 can be formed.
Wherein, for example BCB be can use,, refractive index ratio core layer 806a, polyimides that 806b is low for example can be used as the material of coating layer 805a, 807a, 805b, 807b as the material of core layer 806a, 806b.
Reflection can be reduced like this, the bend loss in slot part A71 and optical waveguide region R 72 can be reduced simultaneously on the border of optical waveguide region R 71 and optical waveguide region R 72.
For optical waveguide region R 61 middle horizontal squares that are suppressed at Figure 10 to bend loss, also can be replaced as the cross section structure that cuts off at the XIII-XIII of Figure 10 line the cross section structure of Figure 13.
Figure 13 is the sectional view along the brief configuration on the integrated light guide road of the direction indication ninth embodiment of the invention vertical with the fiber waveguide direction.In Figure 13, sequential cascade core layer 902 and top coating layer 903 on semiconductor substrate 901.The top of top coating layer 903, core layer 902 and semiconductor substrate 901 forms embedding layer 904a, 904b along the etched ribbon that is processed into of fiber waveguide direction respectively in the both sides, top of top coating layer 903, core layer 902 and semiconductor substrate 901.
As semiconductor substrate 901, top coating layer 903 and embedding layer 904a, 904b, for example can use InP, core layer 902, for example can use emission wavelength is the GaInAsP of 1.3 μ m.
Reflection can be reduced like this, the bend loss in optical waveguide region R 61 can be reduced simultaneously on the border of optical waveguide region R 61 and optical waveguide region R 62.
For the bend loss of the transverse direction in the optical waveguide region R 62 that is suppressed at Figure 10, the cross section structure that cuts off at the XIV-XIV of Figure 10 line can be replaced as the cross section structure of Figure 14.
Figure 14 is the sectional view along the brief configuration on the integrated light guide road of the direction indication tenth embodiment of the invention vertical with the fiber waveguide direction.In Figure 14, on semiconductor substrate 1001, be formed with the core layer 1002 of coating layer 1003 around surrounding.As semiconductor substrate 1001, for example can use InP, as the material of core layer 1002, for example can use BCB, as the material of coating layer 1003, for example can use the low polyimides of refractive index ratio core layer 1002.
Reflection can be reduced like this, the bend loss in optical waveguide region R 62 can be reduced simultaneously on the border of optical waveguide region R 61 and optical waveguide region R 62.
About the not special restriction of the shape of core layer 702a, the 702b of Figure 11, for example can make the separation limitation heterostructure (SCH) of stratiform and inclination refractive index (GI-) SCH that the refractive index segmentation is changed with the refractive index materials between the refractive index of refractive index with core layer central portion and coating layer.
In semiconductor laser, use under the situation of this structure, can use the active region as core, its shape is no matter be that main body, MQW (multiple quantum trap), quantum wire, quantum dot can be suitable for, and also can use about the waveguide line structure of active region in addition and imbed pn, ridge structure, semi-insulating structure, the high platform structure etc. imbedded.About the combination of also unqualified InP of material and GaInAsP, all applicable in addition for any materials such as GaAs, AlGaAs, InGaAs, GaInNAs.
Transverse direction limitation about Figure 13 is not provided with special restriction in addition, can use general ridge waveguide road commonly used and Gao Tai waveguide road etc. as the semiconductor waveguide line structure.
Optical waveguide region R 62 about Figure 14 is not provided with special restriction in addition, can use ridge waveguide road (ridge waveguide) and high platform waveguide road (high-mesa waveguide) etc. yet.
Be described in more detail the operating principle of the embodiment of Figure 11 below.
In Figure 11, making the refractive index of equal value of optical waveguide region R 61 and semiconductor board B61 is 3.12, and the refractive index of equal value that makes optical waveguide region R 62 and slot part A61 is 1.54, according to (3) formula, in the reflection of each regional interface generation about 12%.The total reflectivity in each regional interface be not simply add and, be necessary to consider the phase place of reflected wave.Even just intensity is identical, phasing back, light is cancelled out each other.Therefore by the thickness adjustment of slot part A61 and semiconductor board B61, make the reflected wave phase place optimization on each regional interface, can reduce the total reflectivity at these interfaces.
Figure 15 is the reflectivity of the coupling part on the integrated light guide road of expression Figure 11 and the width d of slot part A61 1Thickness d with semiconductor board B61 2The diagram of relation.Figure 15 is the refractive index N of equal value that makes optical waveguide region R 61 and semiconductor board B61 in addition 1Be 3.12, make the refractive index N of equal value of optical waveguide region R 62 and slot part A61 2Be 1.54, represent width d with respect to slot part A61 with contour 1Thickness d with semiconductor board B61 2The diagram of reflectivity.The words that this external application is more popular, each an opposite side the axle on represent optical length.
In Figure 15, heavy line represents not form slot part A61 and semiconductor board B61, directly the reflectivity (about 12%) under the situation of optical waveguide region R 61 and optical waveguide region R 62 joints.Just establishing incident wavelength is λ, and the optical length of expression slot part A61 or semiconductor board B61 is the straight line of λ/2 o'clock, is near the N that dots 1d 1+ N 2d 2The curve of the straight line of=λ/4 * (21+1) (1 is integer).
Being almost in the leg-of-mutton zone of surrounding with these heavy lines, than the joint on simple two waveguide roads, reflectivity is little.These delta-shaped regions can be similar to following scope to be represented.
N 1d 1＞λ/2n、N 2d 2＞λ/2m、N 1d 1+N 2d 2＜λ/4(21+1)…(6)
(l, m, n are the integer that satisfies the n+m=l relation)
Or
N 1d 1＜λ/2n、N 2d 2＜λ/2m、N 1d 1+N 2d 2＞λ/4(21+1)…(7)
(l, m, n are the integer that satisfies the n+m=l-1 relation)
Wherein represent near the triangle of initial point as usefulness, leg-of-mutton each limit is being departed among the regional c of triangle center λ/64, can make reflectivity at (with respect to the joint on simple two waveguide roads about 80%) below 10%, same in only departing from the regional b of λ/32, can make reflectivity at (with respect to the joint on simple two waveguide roads about 40%) below 5%, same in only departing from the regional a of λ/16, can make reflectivity at (with respect to the joint on simple two waveguide roads about 8%) below 1%.Zone d be the low zone of reflectivity than with simple two waveguide roads joint the time.
Just establishing the amount that each limit of triangle is reduced is δ x, represents that its each limit is
N 1d 1＞nλ/2±δx
N 2d 2＞mλ/2±δx
N 1d 1+N 2d 2＝λ/4×(21+1)±δx
Other delta-shaped region too.
Will obtain areflexia in addition, making m, n is integer, satisfy
N 1d 1+N 2d 2＝±λ/(2π)[cos -1{±(N 1 2+N 2 2)/(N 1+N 2) 2}+2mπ]
…(8)
N 1d 1-N 2d 2＝λ/2n …(9)
This is equivalent to the approximate centre of each delta-shaped region.
In the above-described embodiment, to about the material method identical with the material of optical waveguide region R 62 that is filled among the slot part A61 is illustrated, but also can make the material that is filled among the slot part A61 different mutually with the material of optical waveguide region R 62.Optical waveguide region R 61 also may not be identical layer structure with semiconductor board B61 in addition.
Figure 16 is the sectional view of the integrated light guide road brief configuration of expression tenth embodiment of the invention.This tenth embodiment is the embodiment that subtend has disposed the structure of Figure 12.In Figure 16, form optical waveguide region R 111, slot part A111, semiconductor board B111, optical waveguide region R 112, semiconductor board B112, slot part A112 and optical waveguide region R 113 in proper order in semiconductor substrate 1101 upper edge fiber waveguide directions.
The refractive index that wherein can set optical waveguide region R 111, R113 and optical waveguide region R 112 becomes different mutually, for example, optical waveguide region R 111, R113 can constitute with semi-conducting material, and optical waveguide region R 112 can constitute with the material beyond the semiconductor.
Can be in slot part A111, A112 material beyond the filling semiconductor, for example can fill material identical materials with optical waveguide region R 112.Semiconductor board B111, B112 can constitute in the mode identical with the structure of optical waveguide region R 111, R113 in addition.Slot part A111, A112 and semiconductor board B111, B112 are configured to cross (crosscut) fiber waveguide direction in addition, and preferred slot part A111, A112 can relative fiber waveguide direction arranged perpendicular with semiconductor board B111, B112.
The thickness of the width of slot part A111 and semiconductor board B111 can be set at the light of the boundary reflection of optical waveguide region R 111 and slot part A111 because of at the light of the boundary reflection of slot part A111 and semiconductor board B111, weaken at the light of the boundary reflection of semiconductor board B111 and optical waveguide region R 112.
The thickness of the width of slot part A112 and semiconductor board B112 can be set at the light of the boundary reflection of optical waveguide region R 112 and semiconductor board B112 because of at the light of the boundary reflection of semiconductor board B112 and slot part A112, weaken at the light of the boundary reflection of slot part A112 and optical waveguide region R 113.
Just stacked core layer 1101a～1101d on semiconductor substrate 1101 distinguishes stacked top coating layer 1103a～1103d on core layer 1101a～1101d.As semiconductor substrate 1101 and top coating layer 1103a～1103d, for example can use InP, as core layer 1101a～1101d, for example can use emission wavelength is the GaInAsP of 1.3 μ m.
Carry out etching and processing by the semiconductor substrate 1101 that sequential cascade is had core layer 1101a～1101d and top coating layer 1103a～1103d, form groove 1104a, the 1104c of relative fiber waveguide direction arranged perpendicular, form the recess 1104b that only separates the predetermined distance configuration with groove 1104a, 1104c at semiconductor substrate 1101 simultaneously.
By the core layer 1106a that clamps with coating layer 1105a, 1107a is imbedded groove 1104a, simultaneously the core layer 1106c that clamps with coating layer 1105c, 1107c is imbedded groove 1104c, can form slot part A111, the A112 at the interface that is configured in optical waveguide region R 111, R113 respectively.
By the core layer 1106b that clamps with coating layer 1105b, 1107b is imbedded recess 1104b, the optical waveguide region R 112 that separates semiconductor board B111, B112 configuration from slot part A111, A112 respectively can formed.
Wherein, for example can use BCB,, for example can use the low polyimides of refractive index ratio core layer 1106a～1106c as the material of coating layer 1105a～1105c, 1107a～1107c as the material of core layer 1106a～1106c.
Can reduce the reflection between the optical waveguide when being integrated on the same semiconductor substrate 1101 to the optical waveguide beyond optical waveguide and the semiconductor like this, simultaneously can be being integrated in the semiconductor light wave guide passage midway by having the optical waveguide that the refractive index materials different with semiconductor constitute.Therefore can improve the degree of freedom of waveguide road design, realize having the optical waveguide of only using the unavailable new features of semiconductor.
Because the embodiment of Figure 16 is the structure that subtend disposes Figure 12,, can use material and structure beyond this explanation so the material of waveguide road, core layer and the coating layer of the embodiment of Figure 16 and structure are not provided with special restriction.
In the embodiment of Figure 16, the method that subtend is only disposed 1 picture group, 12 structures is illustrated, and also can be connected in series the structure of the Figure 12 more than 3.Wherein by using the structure of Figure 12, can suppress the reflectivity between each optical waveguide, can suppress the reflectivity of integrated light guide road integral body.
Consider the optical length on above-mentioned integrated light guide road, semi-conductive refractive index Yin Wendu raises and increases, and promptly the temperature differential coefficient of refractive index is positive, and environment temperature raises, and the optical length of optical waveguide is elongated.
For example also can use material to constitute the optical waveguide region R 62 of Figure 11 and the optical waveguide region R 112 of Figure 16 with negative refractive index differential temperature coefficient.Even causing because of variations in temperature under the situation that the optical length of optical waveguide changes one by one like this, the optical length that can suppress optical waveguide integral body is with variation of temperature.Material as having negative refractive index differential temperature coefficient for example can use PMMA.
Figure 17 is the sectional view of the integrated light guide road brief configuration of expression eleventh embodiment of the invention.Integrated in the structure that this 11 embodiment is Figure 16 semiconductor laser.In Figure 17, form optical waveguide region R 121, slot part A121, semiconductor board B121, optical waveguide region R 122, semiconductor board B122, slot part A122 and optical waveguide region R 123 in proper order, on optical waveguide region R 121 and optical waveguide region R 123, be formed with laser diode in semiconductor substrate 1201 upper edge fiber waveguide directions.
The refractive index that wherein can set optical waveguide region R 121, R123 and optical waveguide region R 122 for is different mutually, for example optical waveguide region R 121, R123 can constitute with semi-conducting material, and optical waveguide region R 122 can constitute with the material beyond the semiconductor.
Can be in slot part A121, A122 material beyond the filling semiconductor, for example can fill and optical waveguide region R 122 identical materials.Semiconductor board B121, B122 can constitute in the mode identical with the structure of optical waveguide region R 121, R123 in addition.Slot part A121, A122 and semiconductor board B121, B122 are configured to cross the fiber waveguide direction in addition, but the preferred relative fiber waveguide direction of slot part A121, A122 arranged perpendicular with semiconductor board B121, B122.
The thickness of the width of slot part A121 and semiconductor board B121 can be set at the light of the boundary reflection of optical waveguide region R 121 and slot part A121 because of at the light of the boundary reflection of slot part A121 and semiconductor board B121, weaken at the light of the boundary reflection of semiconductor board B121 and optical waveguide region R 122.
The thickness of the width of slot part A122 and semiconductor board B122 can be set at the light of the boundary reflection of optical waveguide region R 122 and semiconductor board B122 because of at the light of the boundary reflection of semiconductor board B122 and slot part A122, weaken at the light of the boundary reflection of slot part A122 and optical waveguide region R 123.
Just stacked active layer 1202a, 1202d and core layer 1201b, 1201c on semiconductor substrate 1201, top coating layer 1203a, 1203d, 1203b, the 1203c of and semiconductor substrate 1201 different conductivity types stacked on active layer 1201a, 1201d respectively with core layer 1202b, 1202c.As semiconductor substrate 1201 and top coating layer 1203a～1203d, for example can use InP, as active layer 1202a, 1202d and core layer 1202b, 1202c, for example can use wavelength is the GaInAsP of 1.55 μ m.For example can make semiconductor substrate 1201 be the n type in addition, making top coating layer 1203a～1203d is the p type.
By the semiconductor substrate 1201 that is laminated with top coating layer 1203a～1203d on active layer 1202a, 1202d and core layer 1202c, 1202c is carried out etching and processing, form groove 1204a, the 1204c of relative fiber waveguide direction arranged perpendicular, form the recess 1204b that only separates the predetermined distance configuration with groove 1204a, 1204c at semiconductor substrate 1201 simultaneously.Can dispose active layer 1202a, 1202d respectively corresponding to optical waveguide region R 121, R123 like this, and dispose core layer 1202b, 1202c respectively corresponding to semiconductor board B121, B122.
By the core layer 1206a that clamps with coating layer 1205a, 1207a is imbedded groove 1204a, simultaneously the core layer 1206c that clamps with coating layer 1205c, 1207c is imbedded groove 1204c, can form slot part A121, the A122 at the interface that is configured in optical waveguide region R 121, R123 respectively.
By the core layer 1206b that clamps with coating layer 1205b, 1207b is imbedded recess 1204b, can form from slot part A121, A122 and separate semiconductor board B121, B122 respectively and the optical waveguide region R 122 that disposes.
By on top coating layer 1203a, 1203d, forming electrode 1208a, 1208b respectively, form electrode 1208c simultaneously at semiconductor substrate 1201 back sides in addition, can on optical waveguide region R 121, optical waveguide region R 123, form laser diode respectively.
Wherein, for example can use BCB,, for example can use the low polyimides of refractive index ratio core layer 1206a～1206c as the material of coating layer 1205a～1205c, 1207a～1207c as the material of core layer 1206a～1206c.
Also can constitute optical waveguide region R 122 in addition, for example can use PMMA with material with negative refractive index temperature differential coefficient.The resonator length relative temperature is fixed, can suppress the dependence of the vibration wavelength of semiconductor laser temperature.
Have again and can on optical waveguide region R 121 and R123, form diffraction grating, give wavelength selectivity, can make distributed feed-back type (DFB) semiconductor laser and distributed reflectors (DBR) etc.
The structure example of active layer 1202a, 1202d and core layer 1202b, 1202c is as making the separation limitation heterostructure (SCH) of stratiform and inclination refractive index (GI-) SCH that the refractive index segmentation is changed with the refractive index materials between the refractive index of refractive index with active layer or core layer central portion and coating layer.
The shape of active layer 1202a, 1202d is no matter be that main body, MQW (multiple quantum trap), quantum wire, quantum dot can be suitable for, and also can use about the waveguide line structure of active region in addition and imbed pn, ridge structure, imbeds heterostructure, high platform structure etc.About the combination of also unqualified InP of material and GaInAsP, all utilize suitable in addition for any materials such as GaAs, AlGaAs, InGaAs, GaInNAs.
Figure 18 is the stereogram of the integrated light guide road coupling unit brief configuration of expression twelveth embodiment of the invention.This 12 embodiment can enlarge the embodiment that can reduce in the wave-length coverage of the reflection on the border of optical waveguide region R 131 and optical waveguide region R 132 by 2 couples of slot part A131, A132 and semiconductor board B131, B132 are set.
In Figure 18, be formed with optical waveguide region R 131, slot part A131, semiconductor board B131, slot part A132, semiconductor board B132 and optical waveguide region R 132 in proper order in semiconductor substrate 711 upper edge fiber waveguide directions.Wherein the refractive index of optical waveguide region R 131 and optical waveguide region R 132 can be set at mutual differently, and for example optical waveguide region R 131 can constitute with semi-conducting material, and optical waveguide region R 132 can constitute with the material beyond the semiconductor.
Can be in slot part A131, A132 material beyond the filling semiconductor, for example can fill material identical materials with optical waveguide region R 132.Semiconductor board B131, B132 can constitute in the mode identical with the structure of optical waveguide region R 131 in addition.Slot part A131, A132 and semiconductor board B131, B132 are configured to cross the fiber waveguide direction in addition, and preferred slot part A131, A132 can relative fiber waveguide direction arranged perpendicular with semiconductor board B131, B132.
The thickness of the width of slot part A131, A132 and semiconductor board B131, B132 can be set at the light of the boundary reflection of optical waveguide region R 131 and slot part A131 because of at the light of the boundary reflection of slot part A131 and semiconductor board B131, weaken at the light of the boundary reflection of the light of the boundary reflection of light, slot part A132 and the semiconductor board B132 of the boundary reflection of semiconductor board B131 and slot part A132 and semiconductor board B132 and optical waveguide region R 132.
Even like this optical waveguide beyond semiconductor light wave guide passage and the semiconductor is integrated under the situation on the same semiconductor substrate 711, can reduce the reflection between these optical waveguides, can in the degree of freedom that keeps the design of waveguide road, can realize having the optical waveguide of only using the unavailable new features of semiconductor.
By the semiconductor substrate 711 that is formed with optical waveguide region R 131 is carried out etching and processing, can on semiconductor substrate 711, form slot part A131, A132 and semiconductor board B131, B132 in addition.Therefore do not form antireflection film, can reduce reflection, can easily handle the integrated of optical waveguide on the border of optical waveguide region R 131 and optical waveguide region R 132 at the interface of optical waveguide region R 131 and optical waveguide region R 132.
Utilize and adjust slot part A131, the width of A132 and the thickness of semiconductor board B131, B132, can enlarge the wave-length coverage that can reduce in the edge reflection of optical waveguide region R 131 and optical waveguide region R 132, go for WDM optical networks etc., realize having the optical waveguide of only using the unavailable new features of semiconductor simultaneously.
Figure 19 is along XIX, the XX-XIX of the fiber waveguide direction of Figure 18, the sectional view that the XX line cuts off.In Figure 19, stacked core layer 712a～712c on semiconductor substrate 711, the stacked top coating layer 713a～713c of difference on core layer 712a～712c.As semiconductor substrate 711 and top coating layer 713a～713c, for example can use InP, as core layer 712a～712c, for example can use emission wavelength is the GaInAsP of 1.3 μ m.
Carry out etching and processing by the semiconductor substrate 711 that sequential cascade is had core layer 712a～712c and top coating layer 713a～713c, form the width d of relative fiber waveguide direction arranged perpendicular 1Groove 714a, and formation and groove 714a only separate predetermined distance d 2The width d of configuration 3Groove 714b, and on semiconductor substrate 711, form with groove 714b and only separate predetermined distance d 4The step 714c of configuration.
Only separate thickness d by in groove 714a, 714b, imbedding packing material 715a, 715b respectively, can form the slot part A131 on the interface that is configured in optical waveguide region R 131, can forming with slot part A131 simultaneously 2The slot part A132 of semiconductor board B131 configuration.
In addition by optical waveguide material 715c is imbedded step 714c, can form with slot part A132 and only separate thickness d 4The optical waveguide region R 132 of semiconductor board B132 configuration.
Wherein, can use to have the refractive index material different, for example can exemplify BCB with semiconductor as packing material 715a, 715b and optical waveguide material 715c.In this case, the refractive index of equal value of optical waveguide region R 131 and semiconductor board B131, B132 can be 3.12, and the refractive index of equal value of optical waveguide region R 132 and slot part A131, A132 can be 1.54.
Like this can be in the reflection of wide wave-length coverage minimizing on the border of optical waveguide region R 131 and optical waveguide region R 132, can be integrated in mutual different optical waveguide region R 131 and the optical waveguide region R 132 of refractive index on the same semiconductor substrate 711 simultaneously, can realize having the optical waveguide of only using the unavailable new features of semiconductor.
Bend loss in slot part A131, A132 and optical waveguide region R 132 is little of negligible degree under the short situation of their propagation distances, but the propagation distance in slot part A131, A132 and optical waveguide region R 132 is long, and bend loss can not be ignored.
Therefore also the cross section structure of the Figure 19 that cuts off at the XX-XX of Figure 18 line can be replaced as the cross section structure of Figure 20.
Figure 20 is the sectional view along the integrated light guide road coupling unit brief configuration of fiber waveguide direction indication thriteenth embodiment of the invention.This 13 embodiment be resemble Figure 19 embodiment the core layer is set on slot part A131, A132 and optical waveguide region R 132.
In Figure 20, be formed with optical waveguide region R 141, slot part A141, semiconductor board B141, slot part A142, semiconductor board B142 and optical waveguide region R 142 in proper order in semiconductor substrate 811 upper edge fiber waveguide directions.
Just stacked core layer 812a～812c on semiconductor substrate 811 distinguishes stacked top coating layer 813a～813c on core layer 812a～812c.As semiconductor substrate 811 and top coating layer 813a～813c, for example can use InP, as core layer 812a～812c, for example can use emission wavelength is the GaInAsP of 1.3 μ m.
Carry out etching and processing by the semiconductor substrate 811 that sequential cascade is had core layer 812a～812c and top coating layer 813a～813c, form the groove 814a of relative fiber waveguide direction arranged perpendicular, and formation and groove 814a only separate the groove 814b of predetermined distance configuration, and then only separate the step 814c of predetermined distance configuration on semiconductor substrate 811 with groove 814b.
By the core layer 816a that clamps with coating layer 815a, 817a is imbedded groove 814a, simultaneously the core layer 816b that clamps with coating layer 815b, 817b is imbedded groove 814b, the slot part A141 that is configured in the interface of optical waveguide region R 141 can be formed, the slot part A142 that separates semiconductor board B141 configuration with slot part A141 can be formed simultaneously.
By the core layer 816c that clamps with coating layer 815c, 817c is imbedded step 814c, can form the optical waveguide region R 142 that separates semiconductor board B142 configuration with slot part A142.
Wherein, for example can use BCB,, for example can use the low polyimides of refractive index ratio core layer 816a～816c as the material of coating layer 815a～815c, 817a～817c as the material of core layer 816a～816c.
Reflection can be reduced like this, the bend loss in slot part A141, A142 and optical waveguide region R 142 can be reduced simultaneously on the border of optical waveguide region R 141 and optical waveguide region R 142.
For optical waveguide region R 131 middle horizontal squares that are suppressed at Figure 19 to bend loss, also can be replaced as the cross section structure that cuts off at the XIII-XIII line of Figure 18 the cross section structure of Figure 13.In addition for optical waveguide region R 132 middle horizontal squares that are suppressed at Figure 18 to bend loss, also can be replaced as the cross section structure that cuts off at the XIV-XIV line of Figure 18 the cross section structure of Figure 14.
About the not special restriction of the shape of core layer 712a, the 712b of Figure 19, for example can make the separation limitation heterostructure (SCH) of stratiform and inclination refractive index (GI-) SCH that the refractive index segmentation is changed with the refractive index materials between the refractive index of refractive index with core layer central portion and coating layer.
In semiconductor laser, use under the situation of this structure, can use the active region as core, its shape is no matter be that main body, MQW (multiple quantum trap), quantum wire, quantum dot can be suitable for, and also can use about the waveguide line structure of active region in addition and imbed pn, ridge structure, semi-insulating structure, the high platform structure etc. imbedded.About the combination of also unqualified InP of material and GaInAsP, all utilize suitable in addition for any materials such as GaAs, AlGaAs, InGaAs, GaInNAs.
Employing makes the optical waveguide region R 131 of Figure 19 and the refractive index N of equal value of semiconductor board B131, B132 1Be 3.12, the refractive index N of equal value of optical waveguide region R 132 and slot part A131, A132 2Be 1.54, in the optical waveguide that constitutes with light waveguide area R131, slot part A131, semiconductor board B131 and slot part A132, for the width d of slot part A131 1Thickness d with semiconductor board B131 2Reflectivity identical with Figure 15.
Therefore in order to reduce the reflectivity of the optical waveguide that optical waveguide region R 131, slot part A131, semiconductor board B131 and slot part A132 constitute, can set the width d of slot part A131 in the mode of the relation that satisfies (6) formula or (7) formula 1Thickness d with semiconductor board B131 2
For the reflectivity that makes the optical waveguide that optical waveguide region R 131, slot part A131, semiconductor board B131 and slot part A132 constitute is 0, can set the width d of slot part A131 in the mode of the relation that satisfies (8) formula or (9) formula 1Thickness d with semiconductor board B131 2
Be reflected into 0 for Figure 19 of optical waveguide integral body make to(for) certain wavelength X, with slot part A132 the overall structure of Figure 19 is cut apart, as imagining optical waveguide that is made of optical waveguide region R 131, slot part A131, semiconductor board B131 and slot part A132 and the optical waveguide that is made of slot part A132, semiconductor board B132 and optical waveguide region R 132, the reflectivity that must make these both sides' optical waveguide is 0.
Therefore on the reflectivity that makes the optical waveguide that is made of optical waveguide region R 131, slot part A131, semiconductor board B131 and slot part A132 was 0 basis, must make the reflectivity of the optical waveguide that is made of slot part A132, semiconductor board B132 and optical waveguide region R 132 was 0.
The reflectivity that wherein makes the optical waveguide that is made of slot part A132, semiconductor board B132 and optical waveguide region R 132 is that 0 condition can provide with following (10) formula.
N 2d 4＝λ/2n …(10)
(n is an integer)
Figure 21 uses slot part A132, semiconductor board B132 and the reflectivity of the optical waveguide that optical waveguide region R 132 constitutes and the thickness d of semiconductor board B132 of Figure 19 for expression 4The diagram of relation.Incident wavelength is 1.55 μ m.
In Figure 21, reflectivity joint (about 12%) than simple two waveguide roads in the zone of representing with oblique line of the optical waveguide that is made of slot part A132, semiconductor board B132 and optical waveguide region R 132 is little.And the little condition of joint on the simple two waveguide roads of luminance factor of the optical waveguide that is made of slot part A132, semiconductor board B132 and optical waveguide region R 132 can be provided by following (11) formula.
λ/2n-λ/16＜N 2d 4＜λ/2n+λ/16 …(11)
(n is an integer)
Wherein the whole optical waveguide of Figure 19 is that left side optical waveguide that is made of optical waveguide region R 131, slot part A131, semiconductor board B131 and slot part A132 and the right side optical waveguide that is made of slot part A132, semiconductor board B132 and optical waveguide region R 132 are formed by connecting, in the rear end of left side optical waveguide and the front end of right side optical waveguide is identical refractive index, so this part does not produce reflection.Even the optical waveguide integral body before therefore considering to cut apart during incident wavelength λ, can make to be reflected into 0 in the coupling joint portion of optical waveguide region R 131 and optical waveguide region R 132.It does not rely on the width d of slot part A132 3
Figure 22 is the width d of the slot part A132 of expression Figure 18 3With diagram with respect to the relation of the reflectivity of incident wavelength.In Figure 22, make N 1=1.54, N 2=3.21, when making incident wavelength λ=1.55 μ m, make d 1=1.08 μ m, d 2=1.00 μ m, d 4=0.966 μ m satisfies reflectivity and is 0 condition.This external application is more general to be talked about, and also represents optical length.
In Figure 22, zone d is the low zone of reflectivity (about 12%) when optical waveguide region R 131 and optical waveguide region R 132 engaged separately, the zone c be emissivity in the zone below 10%, regional b be reflectivity in the zone below 5%, regional a is that reflectivity is in the zone below 1%.
Just by changing the width d of slot part A132 3, can be so that arrive the area change of antiradar reflectivity.For example to widen the wavelength width of regional d, can
λ/2(n+1/4)＜N 1d 3＜λ/2(n+1)
(n is an integer)
To widen the wavelength width of regional a in addition, can
λ/2(m+3/8)＜N 1d 3＜λ/2(m+3/4)
(m is an integer).
In the above-described embodiment, to the packing material method identical with the material of optical waveguide region R 132 in slot part A131, A132 is illustrated, but also can make the packing material in slot part A131, A132 different with the material of optical waveguide region R 132.Optical waveguide region R 131 can not be identical layer structure with semiconductor board B131, B132 in addition.
Figure 23 is the sectional view of the integrated light guide road brief configuration of expression fourteenth embodiment of the invention.This 14 embodiment is by slot part A151～A154 and the mutual alternate configurations of semiconductor board B151～B154, can make the embodiment of the wavelength band steepening that becomes low reflection.
In Figure 23, form optical waveguide region R 151 and optical waveguide region R 152 in semiconductor substrate 911 upper edge fiber waveguide directions, between optical waveguide region R 151 and optical waveguide region R 152, dispose slot part A151～A154 and semiconductor board B151～B154 alternately simultaneously along the fiber waveguide direction.
The refractive index that wherein can set optical waveguide region R 151 and optical waveguide region R 152 for is different mutually, and for example optical waveguide region R 151 can constitute with semi-conducting material, and optical waveguide region R 152 can constitute with the material beyond the semiconductor.
Can be in slot part A151～A154 material beyond the filling semiconductor, for example can fill and optical waveguide region R 152 identical materials.Semiconductor board B151～B154 can constitute in the mode identical with the structure of optical waveguide region R 151 in addition.Slot part A151～A154 and semiconductor board B151～B154 are configured to cross the fiber waveguide direction in addition, and preferred slot part A151～A154 can become with respect to fiber waveguide direction arranged perpendicular with semiconductor board B151～B154.
The mode that the thickness of the width of slot part A151 and semiconductor board B151 can be weakened with the reflectivity on the optical waveguide that is made of optical waveguide region R 14, slot part A151, semiconductor board B151 and slot part A152 is set.
The thickness of the width of slot part A152 and semiconductor board B152 can be set in the mode of the condition that satisfies the optical waveguide areflexia rate that is made of slot part A152, semiconductor board B152 and slot part A153
The thickness of the width of slot part A153, A154 and semiconductor board B153, B154 can be set for respectively identical with the thickness of the width of slot part A152 and semiconductor board B152 in addition.
Wherein set the width of slot part A152 and the thickness of semiconductor board B152 by mode with the condition that satisfies the optical waveguide areflexia rate that constitutes by slot part A152, semiconductor board B152 and slot part A153, simultaneously set the width of slot part A153, A154 and the thickness of semiconductor board B153, B154 in identical with the thickness of the width of slot part A152 and semiconductor board B152 respectively mode, even under the situation of slot part A151～A154 and semiconductor board B151～B154 alternate configurations, also can make the reflectivity among the incident wavelength λ keep certain.
Just stacked core layer 912a～912e on semiconductor substrate 911 distinguishes stacked top coating layer 913a～913e on core layer 912a～912e.As semiconductor substrate 911 and top coating layer 913a～913e, for example can use InP, as core layer 912a～912e, for example can use emission wavelength is the GaInAsP of 1.3 μ m.
Carry out etching and processing by the semiconductor substrate 911 that sequential cascade is had core layer 912a～912e and top coating layer 913a～913e, form the groove 914a～914d of relative fiber waveguide direction arranged perpendicular, form the step 914e that only separates the predetermined distance configuration with groove 914d at semiconductor substrate 911 simultaneously.
By in groove 914a～914d, imbedding packing material 915a～915d respectively, in step 914e, imbed simultaneously optical waveguide material 915e, can between optical waveguide region R 151 and optical waveguide region R 152, form slot part A151～A154 and semiconductor board B151～B154, on semiconductor substrate 911, can form the optical waveguide region R 152 that only separates thick semiconductor board B154 configuration with slot part A154 simultaneously along the mutual alternate configurations of wave guide direction.
Like this by on semiconductor substrate 911, being used to form the etching and processing of slot part 914a～914d, can make the wavelength band steepening that becomes low reflection, even under situation integrated on the same semiconductor substrate 911, can reduce the reflection of specific wavelength between these optical waveguides effectively to the optical waveguide beyond semiconductor light wave guide passage and the semiconductor.
In the above-described embodiment, the method that disposes slot part A151～A154 and semiconductor board B151～B154 repeatedly for 4 times is illustrated, slot part and semiconductor board are disposed more than 3 times or 5 times repeatedly.
Figure 24 is the sectional view of the integrated light guide road brief configuration of expression fifteenth embodiment of the invention.This 15 embodiment is and the structural plane of Figure 19 embodiment to configuration.In Figure 24, be formed with optical waveguide region R 161, slot part A161, semiconductor board B161, slot part A162, semiconductor board B162, optical waveguide region R 162, semiconductor board B163, slot part A163, semiconductor board B164, slot part A164 and optical waveguide region R 163 in proper order in semiconductor substrate 1011 upper edge fiber waveguide directions.
The refractive index that wherein can set optical waveguide region R 161, R163 and optical waveguide region R 162 becomes different mutually, for example optical waveguide region R 161, R163 can constitute with semi-conducting material, and optical waveguide region R 162 can constitute with the material beyond the semiconductor.
Can be in slot part A161～A164 material beyond the filling semiconductor, for example can fill material identical materials with optical waveguide region R 162.Semiconductor board B161～B164 can constitute in the mode identical with the structure of optical waveguide region R 161, R163 in addition.Slot part A161～A164 and semiconductor board B161～B164 are configured to cross the fiber waveguide direction in addition, and preferred slot part A161～A164 can relative fiber waveguide direction arranged perpendicular with semiconductor board B161～B164.
The thickness of the width of slot part A161 and semiconductor board B161 can be set at the light of the boundary reflection of optical waveguide region R 161 and slot part A161 respectively because of at the light of the boundary reflection of slot part A161 and semiconductor board B161, weaken at the light of the boundary reflection of the light of the boundary reflection of light, slot part A162 and the semiconductor board B162 of the boundary reflection of semiconductor board B161 and slot part A162 and semiconductor board B162 and optical waveguide region R 162.
The thickness of the width of slot part A164 and semiconductor board B164 can be set at the light of the boundary reflection of optical waveguide region R 163 and slot part A164 respectively because of at the light of the boundary reflection of slot part A164 and semiconductor board B164, weaken at the light of the boundary reflection of the light of the boundary reflection of light, slot part A163 and the semiconductor board B163 of the boundary reflection of semiconductor board B164 and slot part A163 and semiconductor board B163 and optical waveguide region R 162.
Just stacked core layer 1012a～1012f on semiconductor substrate 1011 distinguishes stacked top coating layer 1013a～1013f on core layer 1012a～1012f.As semiconductor substrate 1011 and top coating layer 1013a～1013f, for example can use InP, as core layer 1012a～1012f, for example can use emission wavelength is the GaInAsP of 1.3 μ m.
Carry out etching and processing by the semiconductor substrate 1011 that sequential cascade is had core layer 1012a～1012f and top coating layer 1013a～1013f, form groove 1014a, 1014b, 1014d, the 1014e of relative fiber waveguide direction arranged perpendicular, form the recess 1014c that only separates the predetermined distance configuration with groove 1014b, 1014d at semiconductor substrate 1011 simultaneously.
By the core layer 1016a that clamps with coating layer 1015a, 1017a is imbedded groove 1014a, simultaneously the core layer 1016b that clamps with coating layer 1015b, 1017b is imbedded groove 1014b, can form the slot part A161, the A162 that are configured between optical waveguide region R 161 and the optical waveguide region R 162.
By the core layer 1016d that clamps with coating layer 1015d, 1017d is imbedded slot part 1014d, the core layer 1016e that clamps with coating layer 1015e, 1017e imbeds recess 1014e, can form the slot part A163, the A164 that are configured between optical waveguide region R 162 and the optical waveguide region R 163.
By the core layer 1016c that clamps with coating layer 1015c, 1017c is imbedded recess 1014c, form the optical waveguide region R 162 that separates semiconductor board B162, B164 configuration respectively with slot part A162, A164.
Wherein, for example can use BCB,, for example can use the low polyimides of refractive index ratio core layer 1016a～1016e as the material of coating layer 1015a～1015e, 1017a～1017e as the material of core layer 1016a～1016e.
Because the embodiment of Figure 24 is the embodiment of subtend configuration Figure 20 structure,, also can use material and structure beyond this explanation so the material and the structure of waveguide road, core layer and the coating layer of the embodiment of Figure 24 is not provided with special restriction.
In the embodiment of Figure 24, the method that subtend is only disposed 1 picture group, 20 structures is illustrated, and also can be connected in series the structure of the Figure 20 more than 3.Wherein, the reflectivity between optical waveguide one by one can be suppressed, the reflectivity of integrated light guide road integral body can be suppressed by using the structure of Figure 20.
Consider the optical length on above-mentioned integrated light guide road, increase owing to semi-conductive refractive index Yin Wendu raises.Just the temperature differential coefficient of refractive index is positive, and environment temperature raises, and the optical length of optical waveguide is elongated.
For example also can use material to constitute the optical waveguide region R 132 of Figure 19 and the optical waveguide region R 162 of Figure 24 with negative refractive index differential temperature coefficient.Even causing because of variations in temperature under the situation that the optical length of optical waveguide changes one by one like this, the optical length that can suppress optical waveguide integral body is with variation of temperature.Material as having negative refractive index differential temperature coefficient for example can use PMMA.
Figure 25 is the sectional view of the integrated light guide road brief configuration of expression sixteenth embodiment of the invention.This 16 embodiment is the integrated embodiment of semiconductor laser in the structure of Figure 24.
In Figure 25, form optical waveguide region R 171, slot part A171, semiconductor board B171, slot part A172, semiconductor board B172, optical waveguide region R 172, semiconductor board B173, slot part A173, semiconductor board B174, slot part A174 and optical waveguide region R 173 in proper order, on optical waveguide region R 171 and optical waveguide region R 173, be formed with laser diode in semiconductor substrate 1111 upper edge fiber waveguide directions.
The refractive index that wherein can set optical waveguide region R 171, R173 and optical waveguide region R 172 for is different mutually, for example optical waveguide region R 171, R173 can constitute with semi-conducting material, and optical waveguide region R 172 can constitute with the material beyond the semiconductor.
Can be in slot part A171～A174 material beyond the filling semiconductor, for example can fill and optical waveguide region R 172 identical materials.Semiconductor board B171～B174 can constitute in the mode identical with the structure of optical waveguide region R 171, R173 in addition.Slot part A171～A174 and semiconductor board B171～B174 are configured to cross the fiber waveguide direction in addition, and preferred slot part A171～A174 can relative fiber waveguide direction arranged perpendicular with semiconductor board B171～B174.
The thickness of the width of slot part A171 and semiconductor board B171 can be set at the light of the boundary reflection of optical waveguide region R 171 and slot part A171 and weaken because of the light at the boundary reflection of the light of the boundary reflection of light, slot part A172 and the semiconductor board B172 of the boundary reflection of light, semiconductor board B171 and the slot part A172 of the boundary reflection of slot part A171 and semiconductor board B171 and semiconductor board B172 and optical waveguide region R 172.
The thickness of the width of slot part A174 and semiconductor board B174 can be set at the light of the boundary reflection of optical waveguide region R 173 and the slot part A174 light because of the boundary reflection of the light of the boundary reflection of light, slot part A173 and the semiconductor board B173 of the boundary reflection of light, semiconductor board B174 and the slot part A173 of the boundary reflection of slot part A174 and semiconductor board B174 and semiconductor board B173 and optical waveguide region R 172 and weaken.
Just stacked active layer 1112a, 1112f and core layer 1112b～1112e on semiconductor substrate 1111, respectively on active layer 1112a, the 1112f with core layer 1112b～1112e on top coating layer 1113a, 1113f, the 1113b～1113e of stacked and semiconductor substrate 1111 different conductivity types.As semiconductor substrate 1111 and top coating layer 1113a～1113f, for example can use InP, as active layer 1112a, 1112f and core layer 1112b～1112e, for example can use wavelength is the GaInAsP of 1.55 μ m.For example can make semiconductor substrate 1111 be the n type in addition, making top coating layer 1113a～1113f is the p type.
By the semiconductor substrate 1111 that is laminated with top coating layer 1113a～1113f on active layer 1112a, 1112f and core layer 1112c～1112e is carried out etching and processing, form groove 1114a, 1114b, 1114d, the 1114e of relative fiber waveguide direction arranged perpendicular, on semiconductor substrate 1111, form the recess 1114c that only separates the predetermined distance configuration with groove 1114ba, 1114d simultaneously.Dispose active layer 1112a, 1112f respectively corresponding to optical waveguide region R 171, R173 like this, dispose core layer 1112b～1112e respectively corresponding to semiconductor board B171～B174 simultaneously.
By the core layer 1116a that clamps with coating layer 1115a, 1117a is imbedded groove 1114a, simultaneously the core layer 1116b that clamps with coating layer 1115b, 1117b is imbedded groove 1114b, can form the slot part A171, the A172 that are configured between optical waveguide region R 171 and the optical waveguide region R 172.
By the core layer 1116d that clamps with coating layer 1115d, 1117d is imbedded slot part 1114d, the core layer 1116e that clamps with coating layer 1115e, 1117e is imbedded slot part 1114e, can form the slot part A173, the A174 that are configured between optical waveguide region R 172 and the optical waveguide region R 173.
By the core layer 1116c that clamps with coating layer 1115c, 1117c is imbedded recess 1114c, can form the optical waveguide region R 172 that separates semiconductor board B172, B174 configuration respectively with slot part A172, A174.
By on top coating layer 1113a, 1113f, forming electrode 1118a, 1118b respectively, form electrode 1118c simultaneously at semiconductor substrate 1111 back sides in addition, can on optical waveguide region R 171 and optical waveguide region R 173, form laser diode respectively.
Wherein, for example can use BCB,, for example can use the low polyimides of refractive index ratio core layer 1116a～1116e as the material of coating layer 1115a～1115e, 1117a～1117e as the material of core layer 1116a～1116e.
Also can constitute optical waveguide region R 172 in addition, for example can use PMMA with material with negative refractive index temperature differential coefficient.The resonator length relative temperature is fixed, can suppress the dependence of the vibration wavelength of semiconductor laser temperature.
Have again and can on optical waveguide region R 171 and optical waveguide region R 173, form diffraction grating etc., give wavelength selectivity, can make distributed feed-back type (DFB) semiconductor laser and distributed reflectors (DBR) etc.
The structure example of active layer 1112a, 1112f and core layer 1112b～1112e is as making the separation limitation heterostructure (SCH) of stratiform or inclination refractive index (GI-) SCH that the refractive index segmentation is changed with the refractive index materials between the refractive index of refractive index with active layer or core layer central portion and coating layer.
The shape of active layer 1112a, 1112f is no matter be that main body, MQW (multiple quantum trap), quantum wire, quantum dot can be suitable for, and also can use about the waveguide line structure of active region in addition and imbed pn, ridge structure, imbeds heterostructure, high platform structure etc.About the combination of also unqualified InP of material and GaInAsP, all utilize suitable in addition for any materials such as GaAs, AlGaAs, InGaAs, GaInNAs.
As described above described, adopt the words of second execution mode of the present invention, do not form antireflection film at the interface of first optical waveguide and second optical waveguide, the reflection that can be the interface of first optical waveguide and second optical waveguide reduces, can be corresponding to optical waveguide integrated, stable and easily on semiconductor substrate, realize having the optical waveguide of only using the unavailable new features of semiconductor.
(with the optical waveguide and the Optical devices of Brewster angle)
Below with reference to figure the integrated light guide road of the 3rd execution mode of the present invention is described.Adopt the words of this 3rd execution mode, can provide the design freedom that makes wave guide direction to improve, reduce the waveguide path loss that causes because of the reflection between the mutually different waveguide road of refractive index and refraction simultaneously and lose, can be on semiconductor substrate integrated optical waveguide and Optical devices.Several specific embodiments to present embodiment describe below.
Figure 26 is the vertical view of the integrated light guide road brief configuration of expression seventeenth embodiment of the invention.In Figure 26, be configured between the first waveguide road 120 and the 3rd waveguide road 1203 at the formation first waveguide road 1201, second waveguide region 1202 and the 3rd waveguide road 1203, the second waveguide regions 1202 on the semiconductor substrate 1200.Wherein can to set refractive index for identical the first waveguide road 1201 and the 3rd waveguide road 1203, and it is different mutually that the first waveguide road 1201 and second waveguide region 1202 can be set refractive index for.For example the first waveguide road 1201 and the 3rd waveguide road 1203 can constitute with semi-conducting material, and second waveguide region 1202 can constitute with the material beyond the semiconductor.As the material of second waveguide region 1202, for example can use deuterate to gather methyl fluoride acrylate (d-PFMA:poly-fluoromethacrylate deuteride) etc. in addition.
The optical propagation direction that the boundary face 1204 of the first waveguide road 1201 and second waveguide region 1202 can be configured to the relative first waveguide road 1201 tilts.The boundary face 1205 on second waveguide region 1202 and the 3rd waveguide road 1203 can be configured to tilt with respect to the extended line of the anaclasis direction on the boundary face 1204 of the first waveguide road 1201 and second waveguide region 1202 in addition.Under the situation that the boundary face 1205 that wherein makes second waveguide region 1202 and the 3rd waveguide road 1203 tilts with respect to the extended line in the anaclasis direction on the boundary face 1204 of the first waveguide road 1201 and second waveguide region 1202, the refractive direction of the light on the boundary face 1205 on second waveguide region 1202 and the 3rd waveguide road 1203 can be set for consistent with the optical propagation direction on the 3rd waveguide road 1203.
Even like this under the situation of second waveguide region 1202 that the configuration refractive index is mutual different between the first waveguide road 1201 and the 3rd waveguide road 1203, reflection on the boundary face 1205 on the boundary face 1204 of the first waveguide road 1201 and second waveguide region 1202 and second waveguide region 1202 and the 3rd waveguide road 1203 is reduced, and can suppress the loss that causes because of refraction.
Just since the boundary face 1204 that the first waveguide road 1201 and second waveguide region 1202 connect between them tilt with respect to the optical propagation direction on the first waveguide road 1201, the reverberation that produces on boundary face 1204 does not turn back to the first waveguide road 1201, can avoid the first waveguide road 1201 to constitute local resonator.The boundary face 1205 that same because second waveguide region 1202 and the 3rd waveguide road 1203 connect between them tilts with respect to the optical propagation direction of second waveguide region 1202, can avoid second waveguide region 1202 and the 3rd waveguide road 1203 to constitute local resonator.
Consistent by the anaclasis direction on the boundary face 1205 that makes second waveguide region 1202 and the 3rd waveguide road 1203 with the optical propagation direction on the 3rd waveguide road 1203, even the light of propagating on the first waveguide road 1201, second waveguide region 1202 and the 3rd waveguide road 1203 also can prevent to spill from the first waveguide road 1201, second waveguide region 1202 and the 3rd waveguide road 1203 producing under the situation of refraction on the boundary face 1205 on boundary face 1204, second waveguide region 1202 and the 3rd waveguide road 1203 of the first waveguide road 1201 and second waveguide region 1202.
Its result can propagate with little the be lost in first waveguide road 1201, second waveguide region 1202 and the 3rd waveguide road 1203 with existing comparing from the light of the first waveguide road, 1201 incidents, penetrates from the 3rd waveguide road 1203.
Under the situation of boundary face 1204 with respect to the optical propagation direction inclination on the first waveguide road 1201 of the first waveguide road 1201 and second waveguide region 1202, the inclination angle of this boundary face 1204 can be set for and satisfy Brewster angle.Under the situation of the boundary face 1205 on this external second waveguide region 1202 and the 3rd waveguide road 1203 with respect to the optical propagation direction inclination of second waveguide region 1202, the inclination angle of this boundary face 1205 can be set for and satisfy Brewster angle.Can become point-symmetric mode this moment with respect to the mid point of second waveguide region 1202, and the first waveguide road 1201 and the 3rd waveguide road 1203 are connected on second waveguide region 1202.
Can reduce the reflection of boundary face 1205 on boundary face 1204, second waveguide region 1202 and the 3rd waveguide road 1203 of the first waveguide road 1201 and second waveguide region 1202 like this, simultaneously the direction on the first waveguide road 1201 and the 3rd waveguide road 1203 is parallel to each other.
Therefore owing to suppress to be inserted with reflection between the waveguide road of the different material of refractive index,, can make incident direction and exit direction consistent with each other even use under the situation of Brewster angle.
Even therefore refractive index mutually different materials be inserted under the situation between the first waveguide road 1201 and the 3rd waveguide road 1203, also can suppress the waveguide path loss loses, the crystalline orientation that simultaneously can flexible Application is suitable for cleavage, etching and imbeds etc., reliability in the time of can suppressing to make the first waveguide road 1201 and the 3rd waveguide road 1203 worsens, realization has the optical waveguide of only using the unavailable new features of semiconductor, can improve the degree of freedom of waveguide road design simultaneously.
Figure 27 is the sectional view of the brief configuration on expression first waveguide 1201 of Figure 26 and the 3rd waveguide road 1203.In Figure 27, sequential cascade has core layer 1301 and top coating layer 1302 on semiconductor substrate 1200.The top of top coating layer 1302, core layer 1301 and semiconductor substrate 1201 becomes ribbon along fiber waveguide direction etching and processing, forms embedding layer 1303,1304 respectively in the both sides, top of top coating layer 1302, core layer 1301 and semiconductor substrate 1200.
First waveguide 1201 and the 3rd waveguide road 1203 are become imbed heterogeneous (BH) structure,, can reduce the bend loss on first waveguide 1201 and the 3rd waveguide road 1203 as carrying out the light limitation at transverse direction.
As semiconductor substrate 1200, top coating layer 1302, embedding layer 1303,1304, for example can use InP, as core layer 1301, for example can use GaInAsP.
Core layer 1301 and top coating layer 1302 sequential cascades under the situation on the semiconductor substrate 1200, molecular beam epitaxial growth), MOCVD (metal organic chemical vaper deposition: metal organic chemical vapor deposition) or ALCVD (atomic layer chemical vaper deposition: etc. epitaxial growth atomic layer chemical vapour deposition) for example can use MBE (molecular beam epitaxy:.
Figure 28 is the vertical view of the integrated light guide road brief configuration of expression eighteenth embodiment of the invention.In Figure 28, be configured between the first waveguide road 1401 and the 3rd waveguide road 1403 on the formation first waveguide road 1401, the second waveguide road 1402 and 1403, the second waveguide roads 1402, the 3rd waveguide road on the semiconductor substrate 1400.The refractive index that wherein can set the first waveguide road 1401 and the 3rd waveguide road 1403 for is identical mutually, and the refractive index that can set the first waveguide road 1401 and the second waveguide road 1402 for is different mutually.For example the first waveguide road 1401 and the 3rd waveguide road 1403 can constitute with semi-conducting material, and the second waveguide road 1402 can constitute with the material beyond the semiconductor.
The optical propagation direction that the boundary face 1404 on the first waveguide road 1401 and the second waveguide road 1402 can be configured to the relative first waveguide road 1401 tilts.The boundary face 1405 on the second waveguide road 1402 and the 3rd waveguide road 1403 can be configured to tilt with respect to the extended line of the anaclasis direction on the boundary face 1404 on the first waveguide road 1401 and the second waveguide road 1402 in addition.Under the situation that the boundary face 1405 that wherein makes the second waveguide road 1402 and the 3rd waveguide road 1403 tilts with respect to the extended line in the anaclasis direction on the boundary face 1404 on the first waveguide road 1401 and the second waveguide road 1402, the refractive direction of the light on the boundary face 1405 on the second waveguide road 1402 and the 3rd waveguide road 1403 can be set for consistent with the optical propagation direction on the 3rd waveguide road 1403.
For example the inclination angle of this boundary face 1404,1405 is set at respectively and satisfies Brewster angle, becomes point-symmetric mode with the mid point with respect to the second waveguide road 1402 simultaneously, and the first waveguide road 1401 and the 3rd waveguide road 1403 are connected on the second waveguide road 1402.
Figure 29 is the sectional view of the brief configuration on the second waveguide road 1402 of expression Figure 28.In Figure 29, on semiconductor substrate 1400, form and surround core layer 1501 on every side with coating layer 1502.As semiconductor substrate 1400, for example can use InP.As coating layer 1502 and core layer 1501, for example can use change fluorine content to gather methyl fluoride acrylate (d-PFMA) etc. in addition with the deuterate that changes refractive index.
Can reduce the bend loss in the second waveguide road 1402 like this, the while can reduce the reflection on the boundary face 1405 on boundary face 1404, the second waveguide road 1402 and the 3rd waveguide road 1403 on the first waveguide road 1401 and the second waveguide road 1402.
The first waveguide road 1401, the second waveguide road 1402 and the 3rd waveguide road 1403 about the first waveguide road 1201 of Figure 26 and the 3rd waveguide road 1203, Figure 28, special restriction is not set, as the structure on semiconductor waveguide road, can use general ridge waveguide road commonly used, high platform waveguide road etc.
About the core layer on waveguide road and the shape of coating layer special restriction is not set, for example can make the separation limitation heterostructure (SCH) of stratiform and inclination refractive index (GI-) SCH that the refractive index segmentation is changed with the refractive index materials between the refractive index of refractive index with core layer central portion and coating layer.
In semiconductor laser, use under the situation of this structure, can use the active region as core, its shape is no matter be that main body, MQW (multiple quantum trap), quantum wire, quantum dot can be suitable for, and also can use about the waveguide line structure of active region in addition and imbed pn, ridge structure, semi-insulating structure, the high platform structure etc. imbedded.About the combination of also unqualified InP of material and GaInAsP, all utilize suitable in addition for any materials such as GaAs, AlGaAs, InGaAs, GaInNAs.
For second waveguide region 1202 of Figure 26 and the second waveguide road 1402 of Figure 28 special restriction is not set yet, for example can uses polyimides and benzocyclobutene (benzocyclobutene) etc. yet.
Consider the optical length on above-mentioned integrated light guide road, increase owing to semi-conductive refractive index Yin Wendu raises.Just the temperature differential coefficient of refractive index is positive, and environment temperature raises, and the optical length of optical waveguide is elongated.
For example also can use material to constitute second waveguide region 1202 of Figure 26 and the second waveguide road 1402 of Figure 28 with negative refractive index differential temperature coefficient.Even causing because of variations in temperature under the situation that the optical length of optical waveguide changes one by one like this, the optical length that can suppress optical waveguide integral body is with variation of temperature.Material as having negative refractive index differential temperature coefficient for example can use PMMA.
Operating principle to the embodiment of Figure 26 and Figure 28 is described in detail below.
Figure 30 incides under the situation on composition surface of refractive index different material for expression light, the schematic diagram of incidence angle and refraction angle relation.
In Figure 30, with from refractive index N 1Material one side to refractive index N 2The incidence angle θ of material one side 1The light of incident at the interface of these materials with refraction angle θ 2Refraction.This moment incidence angle θ 1With refraction angle θ 2Between relation can represent with (4) formula.Incidence angle θ particularly 1Satisfy the relation of representing with (5) formula, incidence angle θ 1With Brewster angle θ BUnder the consistent situation, can make the areflexia of the composition that is parallel to the plane of incidence.
At incidence angle θ 1With Brewster angle θ BUnder the consistent situation, set up by following (12) formula that (4) formula and (5) formula are drawn.
cosθ 1＝sinθ 2
∴θ 2＝π/2-θ 1…(12)
Therefore by becoming point-symmetric mode with mid point with respect to second waveguide region 1402 of Figure 28, the first waveguide road 1401 and the 3rd waveguide road 1403 are connected on second waveguide region 1402, can make the inclination angle on the boundary face 1405 on boundary face 1404, second waveguide region 1402 and the 3rd waveguide road 1403 of the first waveguide road 1401 and second waveguide region 1402 consistent, simultaneously the direction on the first waveguide road 1201 and the 3rd waveguide road 1203 is parallel to each other with Brewster angle.
In addition as can be seen from Figure 30, at refractive index N 1The material inner waveguide direction and at refractive index N 2The direction angulation θ of material inner waveguide 12Can represent with following (13) formula.
θ 12＝π/2-2θ 1 …(13)
Figure 31 is for representing that light is from refractive index N 1Material one side to refractive index N 2The situation of incident of material one side under, wave guide direction angulation θ 12With refractive index ratio N 2/ N 1The diagram of relation.Wave guide direction angulation θ 12In the structure of Figure 26, be the direction and light angle that direction became in second waveguide region 1202 waveguides of light in 1201 waveguides of the first waveguide road, in the structure of Figure 28, be the direction and light angle that direction became in second waveguide road 1402 waveguides of light in 1401 waveguides of the first waveguide road.
In Figure 31, structure with Figure 28 is an example, the refractive index ratio on the first waveguide road 1401 and the second waveguide road 1402 is that 0.9 (for example the refractive index on the first waveguide road 1401 is 3.21 words, the refractive index on the second waveguide road 1402 is 2.89), the first waveguide road 1401 and the second waveguide road, 1402 angulation θ 12Be about 6 degree.Therefore for example the waveguide length on the second waveguide road 1402 is 10 μ m, departs from about 1 μ m from the ejaculation position of the light on the second waveguide road 1402 extended line from the first waveguide road 1401.
The refractive index ratio on the first waveguide road 1401 and the second waveguide road 1402 becomes 0.8, the first waveguide road 1401 and the second waveguide road, 1402 angulation θ in addition 12Be that the refractive index ratio on the first waveguide road 1401 and the second waveguide road 1402 becomes 0.7, the first waveguide road 1401 and the second waveguide road, 1402 angulation θ about 12 degree 12Be that the refractive index ratio on the first waveguide road 1401 and the second waveguide road 1402 becomes 0.6, the first waveguide road 1401 and the second waveguide road, 1402 angulation θ about 20 degree 12Be that the refractive index ratio on the first waveguide road 1401 and the second waveguide road 1402 becomes 0.5, the first waveguide road 1401 and the second waveguide road, 1402 angulation θ about 28 degree 12Be about 37 degree, depart from from the extended line on the first waveguide road 1401 and also will become big.
Therefore the first waveguide road 1401 and the 3rd waveguide road 1403 are configured on the straight line, can not make light waveguide effectively, by corresponding to the first waveguide road 1401 and the second waveguide road, 1402 angulation θ 12With the waveguide length on the second waveguide road 1402, the 3rd waveguide road 1403 is configured to depart from from the extended line on the first waveguide road 1401, can make light waveguide effectively.
Even the track of light is opposite with the direction of advancing too, resemble at N 2＞N 1Situation under, with (3) formula～(5) formula and (12) formula as can be seen, can consider N 2And N 1Replace.
For example the refractive index on the first waveguide road 1401 and the 3rd waveguide road 1403 is 3.12, the refractive index on the second waveguide road 1402 is 1.54, the refractive index ratio on the first waveguide road 1401 and the second waveguide road 1402 is 0.48, from the Brewster angle θ of the first waveguide road 1401 to the second waveguide road 1402 BBe 25.6 degree, as refraction angle θ 2Become 25.6 degree, the angle θ that the first waveguide road 1401 is become with the second waveguide road 1402 12Be 38.8 degree.
On the other hand under the situation on the second waveguide road 1402 and the 3rd waveguide road 1403, as usefulness (3) formula～(5) formula and (12) formula as can be seen, owing to be equivalent to exchange the refractive index on the first waveguide road 1401 and the second waveguide road 1402, so Brewster angle θ BBe 64.4 degree, refraction angle θ 2Become 25.6 degree.
Therefore by becoming point-symmetric mode with mid point with respect to second waveguide region 1402 of Figure 28, the first waveguide road 1401 and the 3rd waveguide road 1403 are connected on second waveguide region 1402, can suppress the reflection between each waveguide road, simultaneously the direction on the first waveguide road 1401 and the 3rd waveguide road 1403 is parallel to each other.Therefore the first waveguide road 1401 is made with the 3rd waveguide road 1403 along identical crystallization direction, can the making of reliability highland have the first waveguide road 1401 and the 3rd waveguide road 1403 of imbedding heterostructure.
Particularly as can be seen from Figure 31, be under about 0.41 the situation at the refractive index ratio on the first waveguide road 1401 and the second waveguide road 1402, the first waveguide road 1401 and the second waveguide road, 1402 angulation θ 12Can be 45 degree, the direction on the first waveguide road 1401 and the 3rd waveguide road 1403 can be vertical mutually.
Even under the situation that the material beyond the first waveguide road 1401 and the 3rd waveguide road 1403 usefulness semiconductors constitutes, principle of the present invention is also identical, the direction on the first waveguide road 1401 and the 3rd waveguide road 1403 can be parallel to each other.
If the refractive index N on the first waveguide road 1401 1, the second waveguide road 1402 refractive index N 2, the reflectivity R of the composition parallel with the plane of incidence can provide with following (14) formula.
R＝|tan(θ 1-sin -1(N 2/N 1sinθ 1))/
tan(θ 1+sin -1(N 2/N 1sinθ 1))| 2 …(14)
Figure 32 incides under the situation on composition surface of refractive index different material for expression light, incidence angle and with the diagram of the relation of the reflectivity of plane of incidence parallel portion.In the example of Figure 32, the refractive index that makes the first waveguide road 1401 is N 1=3.21, the refractive index that makes the second waveguide road 1402 is N 2=1.54.
In Figure 32, press along with incidence angle θ 1Increase, the reflectivity R of the composition of the parallel plane of incidence reduces incidence angle θ gradually 1With Brewster angle θ BReflectivity R became 0 when=25.6 degree were consistent.And incidence angle θ 1Surpass Brewster angle θ B, the reflectivity R of the composition of the parallel plane of incidence sharply increases, and moves closer to angle of total reflection θ A=28.7 degree.
Angle of total reflection θ ACan provide with following (15) formula.
θ A＝sin -1(N 2/N 1) …(15)
Wherein with incidence angle θ 1Be 0 reflectivity R when spending to become 1/3 situation be example, the incidence angle θ that diminishes as reflectivity R 1, can be for from Brewster angle θ B4/5 angle to the special angle θ of Byblos BBig angle of total reflection θ AWith Brewster angle θ B2/3 angular range of difference.The incidence angle θ that diminishes of reflectivity R just 1Can provide with following (16) formula.
4θ B/5≤θ 1≤θ B+2/3(θ A-θ B) …(16)
Like this by making incidence angle θ 1With Brewster angle θ BUnanimity, the boundary face 1404 that just makes the first waveguide road 1401 and the second waveguide road 1402 is with respect to optical propagation direction angulation and Brewster angle θ on the first waveguide road 1401 BUnanimity, the reflectivity that can make the composition of parallel boundary face 1404 is 0.
The general light of propagating on the waveguide road so the light of propagating on the first waveguide road 1401 is not subjected to the loss that boundary face 1404 causes, can see through the second waveguide road 1402 owing to be the TE pattern that only has the composition at parallel edges interface.In addition by making incidence angle θ 1Be set in the scope that (16) formula is represented, can reduce the loss that causes because of reflection.
Figure 33 is the vertical view of the integrated light guide road brief configuration of expression nineteenth embodiment of the invention.In Figure 33, be configured between the first waveguide road 1601 and the 3rd waveguide road 1603 on the formation first waveguide road 1601, the second waveguide road 1602 and 1603, the second waveguide roads 1602, the 3rd waveguide road on the semiconductor substrate 1600.Wherein can to set refractive index for identical the first waveguide road 1601 and the 3rd waveguide road 1603.It is different mutually that the first waveguide road 1601 and the second waveguide road 1602 can be set refractive index for, and the refractive index ratio that can set the first waveguide road 1401 and second waveguide region 1402 for is about 0.41.
The boundary face 1605 on boundary face 1604, the second waveguide road 1602 and the 3rd waveguide road 1603 on the first waveguide road 1601 and the second waveguide road 1602 can be inclined to respect to the incidence angle of light and satisfy Brewster angle respectively.
Can make the first waveguide road 1601 and the second waveguide road, 1602 angulations, the second waveguide road 1602 and the 3rd waveguide road 1603 angulations so respectively is 45 degree, can make the direction on the first waveguide road 1601 and the 3rd waveguide road 1603 vertical mutually, can be reduced in simultaneously the reflection of boundary face 1605 on boundary face 1604, the second waveguide road 1602 and the 3rd waveguide road 1603 on the first waveguide road 1601 and the second waveguide road 1602.Therefore consider from crystalline texture, form under the situation of cleavage surface on the first waveguide road 1601 and the 3rd waveguide road 1603, though not parallel cleavage surface, also can arranged perpendicular.
Figure 34 is the vertical view of the integrated light guide road brief configuration of expression fourth embodiment of the invention.In Figure 34, on semiconductor substrate 1700, form the first waveguide road 1701, the second waveguide road 1702, the 3rd waveguide road 1703, the 4th waveguide road 1704 and the 5th waveguide road 1705.The second waveguide road 1702 is configured between the first waveguide road 1701 and the 3rd waveguide road 1703, and the 4th waveguide road 1704 is configured between the 3rd waveguide road 1703 and the 5th waveguide road 1705.
Wherein can to set refractive index for identical the first waveguide road 1701, the 3rd waveguide road 1703 and the 5th waveguide road 1705, and it is identical mutually that the second waveguide road 1702 and the 4th waveguide road 1704 can be set refractive index for.In addition, can to set refractive index for different mutually the first waveguide road 1701 and the second waveguide road 1702.For example the first waveguide road 1701, the 3rd waveguide road 1703 and the 5th waveguide road 1705 can constitute with semi-conducting material, and the second waveguide road 1702 and the 4th waveguide road 1704 can constitute with the material beyond the semiconductor.
The optical propagation direction that the boundary face 1706 on the first waveguide road 1701 and the second waveguide road 1702 can be configured to the relative first waveguide road 1701 tilts.The boundary face 1707 on the second waveguide road 1702 and the 3rd waveguide road 1703 can be configured to tilt with respect to the extended line in the anaclasis direction of the boundary face 1706 on the first waveguide road 1701 and the second waveguide road 1702 in addition.Under the situation that the boundary face 1707 that wherein makes the second waveguide road 1702 and the 3rd waveguide road 1703 tilts with respect to the extended line in the anaclasis direction of the boundary face 1706 on the first waveguide road 1701 and the second waveguide road 1702, can set for consistent with the optical propagation direction on the 3rd waveguide road 1703 at the refractive direction of the light of the boundary face 1706 on the second waveguide road 1702 and the 3rd waveguide road 1703.
The optical propagation direction that the boundary face 1708 on the 3rd waveguide road 1703 and the 4th waveguide road 1704 can be configured to relative the 3rd waveguide road 1703 tilts.The boundary face 1709 on the 4th waveguide road 1704 and the 5th waveguide road 1705 can be configured to tilt with respect to the extended line in the anaclasis direction of the boundary face 1708 on the 3rd waveguide road 1703 and the 4th waveguide road 1704 in addition.Under the situation that the boundary face 1709 that wherein makes the 4th waveguide road 1704 and the 5th waveguide road 1705 tilts with respect to the extended line in the anaclasis direction of the boundary face 1708 on the 3rd waveguide road 1703 and the 4th waveguide road 1704, the refractive direction of the light on the boundary face 1709 on the 4th waveguide road 1704 and the 5th waveguide road 1705 can be set for consistent with the optical propagation direction on the 5th waveguide road 1705.
For example the inclination angle of these boundary faces 1706～1709 is set at respectively and satisfies Brewster angle, become point-symmetric mode with mid point with respect to the second waveguide road 1702, the first waveguide road 1701 and the 3rd waveguide road 1703 are connected on the second waveguide road 1702, simultaneously become point-symmetric mode, the 3rd waveguide road 1703 and the 5th waveguide road 1705 are connected on the 4th waveguide road 1704 with mid point with respect to the 4th waveguide road 1704.
The reflection of these boundary faces 1706～1709 can be reduced like this, can the degree of freedom of waveguide road design can be improved the 5th waveguide road 1705 configurations of first waveguide road 1701 of input one side and output one side in a straight line simultaneously.
Because the 20 embodiment of Figure 34 is the embodiment that forms with the mode of the structure folded configuration of Figure 28, the material on the first waveguide road 1701, the second waveguide road 1702, the 3rd waveguide road 1703, the 4th waveguide road 1704 and the 5th waveguide road 1705 and shape etc. can be used the content of explanation in the above-described embodiments.
Can be connected in series the structure of a plurality of Figure 34 in addition, can distribute the waveguide region of the material different like this and dispose, can realize having the optical waveguide of only using the unavailable new features of semiconductor with semiconductor.
Figure 35 is the vertical view of the integrated light guide road brief configuration of expression fifth embodiment of the invention.
In Figure 35, be configured between the first waveguide road 1801 and the 3rd waveguide road 1803 on the formation first waveguide road 1801, the second waveguide road 1802 and 1803, the second waveguide roads 1802, the 3rd waveguide road on the semiconductor substrate 1800.Wherein can to set refractive index for identical mutually the first waveguide road 1801 and the 3rd waveguide road 1803, and it is different mutually that the first waveguide road 1801 and the second waveguide road 1802 can be set refractive index for.For example the first waveguide road 1801 and the 3rd waveguide road 1803 can constitute with semi-conducting material, and the second waveguide road 1802 can constitute with the material beyond the semiconductor.
The optical propagation direction that the boundary face 1804 on the first waveguide road 1801 and the second waveguide road 1802 can be configured to the relative first waveguide road 1801 tilts.The boundary face 1805 on the second waveguide road 1802 and the 3rd waveguide road 1803 can be configured to tilt with respect to the extended line of the anaclasis direction on the boundary face 1804 on the first waveguide road 1801 and the second waveguide road 1802 in addition.The first waveguide road 1801 and the 3rd waveguide road 1803 are configured on the same straight line in addition, simultaneously corresponding to the refractive direction on each boundary face 1804,1805, can ways of connecting with the first waveguide road 1801 and the 3rd waveguide road 1803, the second waveguide road 1802 is bent to the garden arc.
For example the inclination angle of this boundary face 1804,1805 is set at respectively and satisfies Brewster angle, become the line symmetrical manner with Central Line simultaneously, the first waveguide road 1801 and the 3rd waveguide road 1803 are connected on the second waveguide road 1802 with respect to the second waveguide road 1802.
Can suppress bend loss like this, the bending of the light that simultaneously can the modifying factor refraction angle causes can improve the degree of freedom of waveguide road design the set positions of the 3rd optical waveguide 1803 at any part simultaneously.
In the 21 embodiment of Figure 10, the bending of the light that causes for the modifying factor refraction angle is illustrated by the method that the bending wave guide passage constitutes second waveguide region 1802, also can constitutes the first waveguide road 1801 or the crooked waveguide road of the 3rd waveguide road 1803 usefulness.
Because the 21 embodiment of Figure 35 is the variation example of Figure 28 structure, the material on the first waveguide road 1801, the second waveguide road 1802 and the 3rd waveguide road 1803 and shape etc. can be used the content of explanation in the above-described embodiments in addition.
Can be connected in series the structure of a plurality of Figure 35 in addition, can distribute the waveguide region of the material different like this and dispose, can realize having the optical waveguide of only using the unavailable new features of semiconductor with semiconductor.
Figure 36 is the stereogram of the integrated light guide road brief configuration of expression 22nd embodiment of the invention.
In Figure 36, on semiconductor substrate 1900, form the first waveguide road WG1, the second waveguide road WG2 and the 3rd waveguide road WG3, the second waveguide road WG2 is configured between the first waveguide road WG1 and the 3rd waveguide road WG3.Wherein can to set refractive index for identical mutually for the first waveguide road WG1 and the 3rd waveguide road WG3, and it is different mutually that the first waveguide road WG1 and the second waveguide road WG2 can set refractive index for.For example the first waveguide road WG1 and the 3rd waveguide road WG3 can constitute with semi-conducting material, and the second waveguide road WG2 can constitute with the material beyond the semiconductor.
The optical propagation direction that the boundary face of the first waveguide road WG1 and the second waveguide road WG2 can be configured to the relative first waveguide road WG1 tilts.The boundary face of the second waveguide road WG2 and the 3rd waveguide road WG3 can be configured to tilt with respect to the extended line of the anaclasis direction on the boundary face of the first waveguide road WG1 and the second waveguide road WG2 in addition.Under the situation that the boundary face that wherein makes the second waveguide road WG2 and the 3rd waveguide road WG3 tilts with respect to the extended line in the anaclasis direction on the boundary face of the first waveguide road WG1 and the second waveguide road WG2, the refractive direction of the light on the boundary face of the second waveguide road WG2 and the 3rd waveguide road WG3 can be set for consistent with the optical propagation direction of the 3rd waveguide road WG3.This external first waveguide road WG1 and the 3rd waveguide road WG3 go up and form laser diode.
Stacked core layer 1901 on semiconductor substrate 1900 just, the top coating layer 1902 of stacked and semiconductor substrate 1900 different conductivity types on core layer 1901.Have again as semiconductor substrate 1900, top coating layer 1902, for example can use InP,, for example can use GaInAsP as core layer 1901.For example can make semiconductor substrate 1901 be the n type in addition, make top coating layer 1902 be the p type.
Carry out etching and processing by the semiconductor substrate 1900 that sequential cascade is had core layer 1901 and top coating layer 1902, make the top of top coating layer 1902, core layer 1901 and semiconductor substrate 1900 form the shape of the first waveguide road WG1 and the 3rd waveguide road WG3. Make embedding layer 1903,1905 respectively in the first waveguide road WG1 and the growth of WG3 both sides, the 3rd waveguide road then, form and imbed heterostructure.Have again as embedding layer 1903,1905, for example can use the InP insulating barrier of doped F e.
Along the border of border, the second waveguide road WG2 and the 3rd waveguide road WG3 of the first waveguide road WG1 and the second waveguide road WG2 top of top coating layer 1902, core layer 1901 and semiconductor substrate 1900 between the first waveguide road WG1 and the 3rd waveguide road WG3 is removed respectively then.
By with shape corresponding to the second waveguide road WG2, the organic material of BCB etc. is imbedded between the first waveguide road WG1 and the 3rd waveguide road WG3, formed the second waveguide road WG2 that is connected on the first waveguide road WG1 and the 3rd waveguide road WG3 on the semiconductor substrate 1900.
This external allocation position that corresponds respectively to the first waveguide road WG1 and the 3rd waveguide road WG3, on top coating layer 1902, form electrode 1906,1907, form electrode 1908 by the back side simultaneously, can on the first waveguide road WG1 and the 3rd waveguide road WG3, form laser diode respectively at semiconductor substrate 1900.
In the 22 embodiment of Figure 36, be that example is illustrated the method that electrode 1906～1908 is set with the structure of Figure 28, but also can electrode be set the structure of above-mentioned Figure 26 or Figure 33～Figure 35.
In the 22 embodiment of Figure 36, owing to be that an active layer that is used for injection current is arranged on the structure on the semiconductor waveguide road, so the material of the first waveguide road WG1, the second waveguide road WG2 and the 3rd waveguide road WG3 and shape etc. can be used the content of explanation in the above-described embodiments.
For example have again and can form diffraction grating, give wavelength selectivity, can make distributed feed-back type (DFB) semiconductor laser and distributed reflectors (DBR) etc. in semiconductor waveguide road part.
Use the material of temperature coefficient for bearing of refractive index in addition as the second waveguide road WG2, can utilize wavelength selectivity to make vibration wavelength single, can obtain temperature change and the constant laser of wavelength simultaneously.
As described above described, adopt the words of the 3rd execution mode of the present invention, even the different mutually material of refractive index is inserted between the fiber waveguide zone, also can suppress the reflection of boundary face, can improve simultaneously the design freedom of wave guide direction, when making the integrated light guide road, can use the crystalline orientation that is suitable for cleavage, etching and imbeds etc. effectively neatly, can be simply and easily realize having optical waveguide and the Optical devices of only using the unavailable new features of semiconductor.
The possibility of utilizing on the industry
As described above, adopt words of the present invention, utilization is in semiconductor substrate, refractive index is applied to transmission region and/or waveguide area with it to the different material of the dependence of temperature, can provide processing and integrated easy, have an optical semiconductor photoreactive semiconductor integrated circuit of only using the unavailable new features of semiconductor.

Claims (49)

1. semiconductor laser is characterized in that having:
The gain regions that wavelength selectivity is arranged;
With described gain regions optical coupled, the transmission region that does not have wavelength selectivity that effective refractive index is different with described gain regions to the dependence of temperature; With
Make the reflector space of the light reflection of propagating at described transmission region.
2. semiconductor laser is characterized in that having:
The gain regions that wavelength selectivity is arranged;
With described gain regions optical coupled, have the effective refractive index material different with described gain regions to the dependence of temperature, there is not the transmission region of gain and wavelength selectivity; With
Make the reflector space that does not have gain of the light reflection of propagating at described transmission region.
3. semiconductor laser is characterized in that having:
The gain regions that wavelength selectivity is arranged;
With described gain regions optical coupled, have the effective refractive index structure different with described gain regions to the dependence of temperature, there is not the transmission region of gain and wavelength selectivity; With
Make the reflector space that does not have gain of the light reflection of propagating at described transmission region.
4. as the described semiconductor laser of claim 1～3, it is characterized in that,
Described reflector space is speculum or the diffraction grating with periodic structure.
5. semiconductor laser is characterized in that having:
First gain regions that wavelength selectivity is arranged;
With the described first gain regions optical coupled, have the effective refractive index material different with described gain regions to the dependence of temperature, there is not the transmission region of gain and wavelength selectivity; With
With described transmission region optical coupled, second gain regions of wavelength selectivity is arranged.
6. semiconductor laser is characterized in that having:
First gain regions that wavelength selectivity is arranged;
With the described first gain regions optical coupled, have the effective refractive index structure different with described gain regions to the dependence of temperature, there is not the transmission region of gain and wavelength selectivity; With
With described transmission region optical coupled, second gain regions of wavelength selectivity is arranged.
7. as each described semiconductor laser in the claim 3,4 or 6, it is characterized in that,
Described structure is at least one the different structure in a layer structure, bed thickness or the waveguide degree of having a lot of social connections.
8. as each described semiconductor laser in the claim 1～7, it is characterized in that,
The product absolute value of the difference of the temperature differential coefficient of the effective refractive index temperature differential coefficient of described gain regions and the effective refractive index of described transmission region and the length of described transmission region is 7.5 * 10 -4More than [μ m/K].
9. as each described semiconductor laser in the claim 1～8, it is characterized in that,
Described transmission region is made of the material different with semi-conductive effective refractive index temperature differential coefficient.
10. as each described semiconductor laser in the claim 1～9, it is characterized in that,
Described transmission region is made of for negative material effective refractive index temperature differential coefficient.
11. as each described semiconductor laser in the claim 1～10, it is characterized in that,
Described gain regions has the diffraction grating that is formed by the real part of complex refractivity index or imaginary part or both periodic perturbations.
12. the semiconductor laser described in claim 11 is characterized in that,
The length of described transmission region is configured to by the definite longitudinal mode spacing of the length sum of the diffraction grating effective length of described gain regions and described transmission region wideer than the stopband width of described diffraction grating.
13. the semiconductor laser described in claim 11 or 12 is characterized in that,
The coupling coefficient of the diffraction grating of described gain regions is greater than 300cm -1
14. as each described semiconductor laser in the claim 1～13, it is characterized in that,
Described gain regions, described transmission region and described reflector space are stacked.
15. as each described semiconductor laser in the claim 1～13, it is characterized in that,
Described gain regions and described transmission region are coupled by the light chopper parts.
16. as each described semiconductor laser in the claim 1～15, it is characterized in that,
Described transmission region be up and down or about in the waveguide line structure of at least one side with light limitation structure.
17. a semiconductor laser is characterized in that having:
Semiconductor substrate;
On described semiconductor substrate, form, have the active layer of distribution catoptric arrangement;
The coating layer that on described active layer, forms;
Remove the removal zone of the part of described active layer and described coating layer; With
Be embedded in the described removal zone temperature compensating layer that effective refractive index is different with described active layer to the dependence of temperature.
18. a semiconductor laser is characterized in that having:
Semiconductor substrate;
Be layered in the distributed Bragg reflecting layer on the described semiconductor substrate;
Be layered on the described distributed Bragg reflecting layer, have the active layer of distribution catoptric arrangement;
Be layered on the described active layer temperature compensating layer that effective refractive index is different with described active layer to the dependence of temperature; With
Be layered in the reflector on the described temperature compensating layer.
19. a semiconductor laser is characterized in that having:
Semiconductor substrate;
On described semiconductor substrate, form, the active layer of distribution catoptric arrangement is arranged;
On described active layer, form, be provided with the coating layer on inclined plane in described active layer end; With
On described coating layer, form the temperature compensating layer that effective refractive index is different with described active layer to the dependence of temperature.
20. an integrated light guide road is characterized in that having:
First optical waveguide;
With the described first optical waveguide optical coupled, second optical waveguide that refractive index is different with described first optical waveguide; With
To cross the mode of described first optical waveguide, only separate the slot part of predetermined distance configuration apart from the interface of described first optical waveguide and described second optical waveguide,
Set apart from the interval at described interface and the width of described slot part, make hyporeflexia on the border of described first optical waveguide and described second optical waveguide.
21. an integrated light guide road is characterized in that having:
First optical waveguide that on semiconductor substrate, forms;
On described semiconductor substrate, form second optical waveguide that refractive index is different with described first optical waveguide; With
Be configured in the border of described first optical waveguide and described second optical waveguide, separating the mode of slot part and vertical waveguide direction with described first optical waveguide, the semiconductor board that on described semiconductor substrate, forms,
Set the width of described slot part and the thickness of described semiconductor board, make at the light of the boundary reflection of described first optical waveguide and described slot part because of weakening at the light of the boundary reflection of described slot part and described semiconductor board and at the light of the boundary reflection of described semiconductor board and described second optical waveguide.
22. integrated light guide as claimed in claim 21 road is characterized in that,
Fill material with refractive index different with the refractive index of described first optical waveguide at described slot part, the refractive index of described first optical waveguide and described semiconductor board is identical, and described second optical waveguide is identical with the refractive index of the material that is filled into described slot part, and refractive index and the width of establishing described slot part respectively are N 1, d 1, the refractive index of described semiconductor board and thickness are N 2, d 2, establishing the waveguide light wavelength is λ, its relation satisfies
N 1d 1＞λ/2n、N 2d 2＞λ/2m、N 1d 1+N 2d 2＜λ/4(2l+1)
(l, m, n are the integer that satisfies the n+m=l relation)
Or
N 1d 1＜λ/2n、N 2d 2＜λ/2m、N 1d 1+N 2d 2＞λ/4(2l+1)
(l, m, n are the integer that satisfies the n+m=l-1 relation).
23. integrated light guide as claimed in claim 21 road is characterized in that,
Fill the material with refractive index different with the refractive index of described first optical waveguide at described slot part, refractive index and the width of establishing described slot part respectively are N 1, d 1, the refractive index of described semiconductor board and thickness are N 2, d 2, establishing the waveguide light wavelength is λ, its relation satisfies
N 1d 1+N 2d 2＝±λ/(2π)[cos -1{±(N 1 2+N 2 2)/(N 1+N 2) 2}+2mπ]
N 1d 1-N 2d 2＝λ/2n
(wherein m, n are integers).
24. an integrated light guide road is characterized in that having:
First optical waveguide that on semiconductor substrate, forms;
On described semiconductor substrate, form second optical waveguide that refractive index is different with described first optical waveguide;
Be configured in the border of described first optical waveguide and described second optical waveguide, to separate the mode of first slot part and vertical waveguide direction, first semiconductor board that on described semiconductor substrate, forms with described first optical waveguide; With
Separating the mode of second slot part and vertical waveguide direction with described first semiconductor board, second semiconductor board that on described semiconductor substrate, forms,
Set the width of described first slot part and described second slot part and the thickness of described first semiconductor board and described second semiconductor board, make at the light of the boundary reflection of described first optical waveguide and described first slot part because of at the light of the boundary reflection of described first slot part and described first semiconductor board, at the light of the boundary reflection of described first semiconductor board and described second slot part, weaken at the light of the boundary reflection of described second slot part and described second semiconductor board and at the light of the boundary reflection of described second semiconductor board and described second optical waveguide.
25. integrated light guide as claimed in claim 24 road is characterized in that,
The thickness of described first semiconductor board and described second semiconductor board is different mutually, or the width of described first slot part and described second slot part is different mutually.
26. as claim 24 or 25 described integrated light guide roads, it is characterized in that,
Fill material at described first slot part with described second slot part with refractive index different with the refractive index of described first optical waveguide, described first optical waveguide, described first semiconductor board are identical with the refractive index of described second semiconductor board, and described second optical waveguide, described first slot part are identical with the refractive index of described second slot part, and refractive index and the width of establishing described first slot part respectively are N 1, d 1, the refractive index of described first semiconductor board and thickness are N 2, d 2, establishing the waveguide light wavelength is λ, its relation satisfies
N 1d 1＞λ/2n、N 2d 2＞λ/2m、N 1d 1+N 2d 2＜λ/4(2l+1)
(l, m, n are the integer that satisfies the n+m=l relation)
Or
N 1d 1＜λ/2n、N 2d 2＜λ/2m、N 1d 1+N 2d 2＞λ/4(2l+1)
(l, m, n are the integer that satisfies the n+m=l-1 relation).
27. as each described integrated light guide road in the claim 24～26, it is characterized in that,
Fill material at described first slot part with described second slot part with refractive index different with the refractive index of described first optical waveguide, described first optical waveguide, described first semiconductor board are identical with the refractive index of described second semiconductor board, and described second optical waveguide, described first slot part are identical with the refractive index of described second slot part, and refractive index and the thickness of establishing described second semiconductor board are N 2, d 4, establishing the waveguide light wavelength is λ, its relation satisfies
λ/2n-λ/16＜N 2d 4＜λ/2n+λ/16
(n is an integer).
28. as each described integrated light guide road in the claim 24～27, it is characterized in that,
Fill material at described first slot part with described second slot part with refractive index different with the refractive index of described first optical waveguide, described first optical waveguide, described first semiconductor board are identical with the refractive index of described second semiconductor board, and described second optical waveguide, described first slot part are identical with the refractive index of described second slot part, if the refractive index of described second slot part and width are N1, d3, if the waveguide light wavelength is λ, its relation satisfies
λ/2(n+1/4)＜N1d3＜λ/2(n+1)
(n is an integer).
29. as each described integrated light guide road in the claim 24～28, it is characterized in that,
Fill material at described first slot part and described second slot part, separate respectively with the slot part of the described second slot part same widths with the semiconductor board of the described second semiconductor board same thickness and dispose repeatedly along wave guide direction with refractive index different with the refractive index of described first optical waveguide.
30. as each described integrated light guide road in the claim 21～29, it is characterized in that,
Described second optical waveguide is made of the material with negative refractive index temperature differential coefficient.
31. an integrated light guide road is characterized in that,
The mutual subtend configuration in each described integrated light guide road in 2 claims 21～30, the end face of described second optical waveguide interconnects.
32. an integrated light guide road is characterized in that,
The described integrated light guide of claim 31 road repeatedly is connected in series repeatedly.
33., it is characterized in that described first optical waveguide has as each described Optical devices in the claim 21～32:
The core layer that on described semiconductor substrate, forms;
Be layered on the described core layer top coating layer that conductivity type is different with described semiconductor substrate;
First electrode that on the coating layer of described top, forms; With
Second electrode that forms at the back side of described semiconductor substrate.
34. as each described Optical devices in the claim 24～33, it is characterized in that,
Described first optical waveguide (or either party at least of described second optical waveguide) has wavelength selectivity.
35. Optical devices is characterized in that having:
Each described integrated light guide road in the claim 24～34.
36. an integrated light guide road is characterized in that having:
The first fiber waveguide zone;
The wave guide direction that is configured to the relative described first fiber waveguide zone with the boundary face in the described first fiber waveguide zone tilts, refractive index and the second different fiber waveguide zone of first fiber waveguide zone; With
With with the boundary face in the described second fiber waveguide zone in refractive direction and the consistent mode of wave guide direction, the 3rd fiber waveguide zone of configuration and the boundary face in the described second fiber waveguide zone.
37. an integrated light guide road is characterized in that, comprising:
Have first optical waveguide and the 3rd optical waveguide of first refractive index and be configured in described first optical waveguide and described the 3rd optical waveguide between the second fiber waveguide zone with second refractive index,
The boundary face that described first optical waveguide and the described second fiber waveguide zone connect into described first optical waveguide and the described second fiber waveguide zone is not orthogonal to the direction of described first optical waveguide,
On the anaclasis direction extended line on the boundary face in described first optical waveguide and the described second fiber waveguide zone, the boundary face that described second fiber waveguide zone and described the 3rd optical waveguide connect into described second fiber waveguide zone and described the 3rd fiber waveguide zone is not orthogonal to described extended line
Anaclasis direction in the boundary face of described second fiber waveguide zone and described the 3rd optical waveguide is consistent with the direction of described the 3rd optical waveguide.
38. integrated light guide as claimed in claim 37 road is characterized in that,
The direction of the direction of described first optical waveguide and described the 3rd optical waveguide is parallel to each other.
39. integrated light guide as claimed in claim 37 road is characterized in that,
The direction of the direction of described first optical waveguide and described the 3rd optical waveguide is vertical mutually.
40. as each described integrated light guide road in the claim 37～39, it is characterized in that,
The boundary face in described first optical waveguide and the described second fiber waveguide zone is equal with respect to the direction angulation of described the 3rd optical waveguide with respect to the boundary face of the direction angulation of described first optical waveguide and described second fiber waveguide zone and described the 3rd optical waveguide, and establishing described first refractive index is N 1, described second refractive index is N 2, the boundary face in described first optical waveguide and the described second fiber waveguide zone satisfies with respect to the direction angulation θ of described first optical waveguide
4θ B/5≤θ≤θ B+2/3(θ A-θ B)
θ B＝tan -1(N 2/N 1)
θ A＝sin -1(N 2/N 1)。
41. integrated light guide as claimed in claim 40 road is characterized in that,
θ＝θ B。
42. as each described integrated light guide road in the claim 37～41, it is characterized in that,
The described second fiber waveguide zone has waveguiding structure.
43. integrated light guide as claimed in claim 42 road is characterized in that,
The described second fiber waveguide zone has circular shape.
44. as each described integrated light guide road in the claim 37～43, it is characterized in that,
Described first optical waveguide and described the 3rd optical waveguide constitute with semiconductor, and the described second fiber waveguide zone constitutes with the material beyond the semiconductor.
45. as each described integrated light guide road in the claim 37～44, it is characterized in that,
If described first refractive index is N 1, described second refractive index is N 2, refractive index ratio N 2/ N 1Or N 1/ N 2Below 0.9.
46. an integrated light guide road is characterized in that,
Each described integrated light guide road is connected in series in a plurality of claims 37～45.
47. as each described Optical devices in the claim 37～46, it is characterized in that,
The some at least of described first optical waveguide or described the 3rd optical waveguide has:
The core layer that on semiconductor substrate, forms;
Be layered on the described core layer top coating layer that conductivity type is different with described semiconductor substrate;
First electrode that on the coating layer of described top, forms; With
Second electrode that forms at the back side of described semiconductor substrate.
48. as each described Optical devices in the claim 37～47, it is characterized in that,
Described first optical waveguide or described the 3rd optical waveguide some at least has wavelength selectivity.
49. Optical devices is characterized in that having:
Each described integrated light guide road in the claim 37～48.
CNB200480000980XA 2003-03-31 2004-03-30 Optical semiconductor device and optical semiconductor integrated circuit Expired - Fee Related CN100377455C (en)

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CN100377455C (en) 2008-03-26

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