CN108155560A - Asymmetric phase-shifted grating and DFB semiconductor laser - Google Patents
Asymmetric phase-shifted grating and DFB semiconductor laser Download PDFInfo
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- CN108155560A CN108155560A CN201611112090.9A CN201611112090A CN108155560A CN 108155560 A CN108155560 A CN 108155560A CN 201611112090 A CN201611112090 A CN 201611112090A CN 108155560 A CN108155560 A CN 108155560A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
- H01S5/12—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers
- H01S5/124—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers incorporating phase shifts
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
- H01S5/12—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers
- H01S5/125—Distributed Bragg reflector [DBR] lasers
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Abstract
This application discloses a kind of asymmetric phase-shifted grating and DFB semiconductor lasers, the phase-shifted grating includes phase shift and the first grating and the second grating positioned at phase shift both sides, the length of first grating is more than the second grating, and the etching depth of first grating and the second grating is identical and screen periods are equal；First grating and the second grating include the apodization section grating of adjacent phase shift setting, and the duty ratio of the apodization section grating gradually changes so that the index modulation of the phase-shifted grating is gradually reduced by two lateral phase shifts.DFB semiconductor laser of the application based on unsymmetric structure phase-shifted grating in phase shift both sides the etching depth of grating and screen periods under the same conditions, changes the position of phase shift, and phase shift is made to deviate the long center of chamber, is biased to laser output.It realizes the asymmetry of Output optical power, increases effective Output optical power of laser；And apodization section grating is introduced in the grating of phase shift both sides, effectively weaken the influence of effects of spatial, improve the single mode yield of DFB semiconductor laser.
Description
Technical field
The application belongs to semiconductor laser field, and in particular to a kind of unsymmetric structure phase-shifted grating and DFB half
Conductor laser.
Background technology
Distributed feed-back (DFB) semiconductor laser, has become essential light source in optical communication network, in DWDM and
It plays an important role in the various wavelength-division multiplex systems such as CWDM.
The light feedback of DFB semiconductor laser is provided by the Bragg grating integrated in the laser, and grating is produced on more
In ducting layer, there is periodic variation along the refractive index of cavity length direction.Bragg grating has different mode in laser chamber
Different reflectivity, it is usually high to the reflectivity near bragg wavelength in one section of region, far from the range of bragg wavelength
Reflectivity it is low.Therefore for different mode existing in laser chamber, loss includes internal loss and end face loss etc..With
The corresponding bragg wavelength of screen periods has minimum loss, gain threshold condition during according to laser lasing, Bradley lattice wave
The gain for threshold value that long corresponding pattern reaches lasing is also just minimum, therefore the cloth when Injection Current reaches the threshold current of laser
Glug pattern can lasing first.In this way, Bragg grating plays the role of good frequency-selecting, Bragg grating is considered as one
The wave filter of narrowband.
In tradition is based on the DFB semiconductor laser of Bragg grating in the case of same external Injection Current, need
Larger effective luminous power is obtained as much as possible, improve the utilization rate to Injection Current.In order to increase DFB semiconductor laser
Effective Output optical power, usually unsymmetric structure is introduced into phase-shifted grating DFB semiconductor laser, common unsymmetrical knot
Structure has：
1) the reflectivity size of two light output ends is asymmetric, i.e., highly reflecting films (HR) are plated on laser end face, another
The mode of coating anti reflection film (AR) realizes the asymmetry of both ends of the surface reflectivity on end face, reaches change DFB semiconductor laser
The purpose of the ratio between the output power of both ends of the surface；
2) grating phase shift is deviateed into filters center position, is biased to laser output.
It is that can plate highly reflecting films (HR) in laser end face if laser is discrete device for structure one,
Another end face plates the mode of anti-reflective film (AR) to distribute the output laser power of two end faces of laser.But highly reflecting films
The influence of random phase can be brought, leads to laser mode hopping.The negative effect that random phase generates laser is unable to control, mesh
Preceding not yet find effectively solves the method that random phase influences.In addition, for following photon integrated chip, i.e., various photonic devices
The chip integrated by selection region growth technology or docking growing technology, can not be realized by the method for plated film
The asymmetric output of Distributed Feedback Laser both ends of the surface laser.For structure two, phase shift deviates center and is biased to laser output, though
The luminous power of output terminal can be improved, but phase shift deviates the influence that center can aggravate effects of spatial, reduce single mode yield.
Invention content
One embodiment of the application provides a kind of asymmetric phase-shifted grating, and the phase-shifted grating includes phase shift and positioned at phase shift two
The first grating and the second grating of side, the length of first grating are more than the second grating, first grating and the second grating
Etching depth it is identical and screen periods are equal；First grating and the second grating include the apodization section of adjacent phase shift setting
Grating, and the duty ratio of the apodization section grating gradually changes so that the index modulation of the phase-shifted grating is by two lateral phases
Shifting is gradually reduced.
In one embodiment, the length of the apodization section grating of first grating and the second grating is identical and index modulation is divided
Cloth is consistent.
In one embodiment, first grating or the second grating have further included and have been set to apodization section grating away from phase shift side
Uniform segment grating, the duty ratio of the uniform segment grating is a steady state value a, 0<a<1.0, wherein：
When the duty ratio of uniform segment grating is a steady state value a, 0<a<When 0.5, the duty ratio of the apodization section grating from phase shift to
Both sides are gradually increased to a along optical grating axial by 0；
When the duty ratio of uniform segment grating is steady state value an a, a=0.5, the duty ratio of the apodization section grating is from phase shift to two
Side is gradually increased to 0.5 by 0 along optical grating axial or gradually decreases to 0.5 by 1.0；
When the duty ratio of uniform segment grating is a steady state value a, 0.5<a<When 1, the duty ratio of the apodization section grating from phase shift to
Both sides gradually decrease to a along optical grating axial by 1.0.
Another embodiment of the application also provides a kind of DFB semiconductor laser, and the DFB semiconductor laser includes DFB
Laser cavity and several epitaxial layers above and below DFB laser cavities, DFB laser cavities include the grating set gradually etching resistance
Only layer, phase-shifted grating, grating coating, the phase-shifted grating include phase shift and the first grating and the second light positioned at phase shift both sides
The etching depth of grid, the first grating and the second grating is identical and screen periods are equal, and the length of first grating is more than second
Grating；First grating and the second grating include the apodization section grating of adjacent phase shift setting, and the apodization section grating
Duty ratio gradually change so that the index modulation of the phase-shifted grating is gradually reduced by two lateral phase shifts.
In one embodiment, the length of the apodization section grating of first grating and the second grating is identical and index modulation is divided
Cloth is consistent.
In one embodiment, first grating or the second grating have further included and have been set to apodization section grating away from phase shift side
Uniform segment grating, the duty ratio of the uniform segment grating is a steady state value a, 0<a<1.0, wherein：
When the duty ratio of uniform segment grating is a steady state value a, 0<a<When 0.5, the duty ratio of the apodization section grating from phase shift to
Both sides are gradually increased to a along optical grating axial by 0；
When the duty ratio of uniform segment grating is steady state value an a, a=0.5, the duty ratio of the apodization section grating is from phase shift to two
Side is gradually increased to 0.5 by 0 along optical grating axial or gradually decreases to 0.5 by 1.0；
When the duty ratio of uniform segment grating is a steady state value a, 0.5<a<When 1.0, the duty ratio of the apodization section grating is from phase shift
To both sides along optical grating axial a is gradually decreased to by 1.0.
In one embodiment, the both sides of the face of the DFB semiconductor laser are coated with anti-reflective film.
In one embodiment, the DFB semiconductor laser is buried heterostructure type laser or ridge waveguide lasers.
Compared with prior art, the application has the advantages that：
The asymmetric phase-shifted grating for introducing apodization is applied to single DFB semiconductor laser, plated film or is not coated with anti-in end face
In the case of reflectance coating, when phase shift being deviateed center and being biased to laser output, the asymmetric output of luminous power is realized, increase has
Imitate Output optical power；And by the consecutive variations of grating duty ratio, apodization is introduced at left and right sides of phase shift, effectively weakens space
The influence of hole-burning effect improves the single mode stability of Distributed Feedback Laser；
The asymmetric phase-shifted grating and DFB semiconductor laser for introducing apodization can be applied to highly integrated photon integrated chip
In, improve effective Output optical power of photon integrated chip end face.
Description of the drawings
Fig. 1 is the structure diagram of symmetrical structure phase-shifted grating in the prior art；
Fig. 2 is the curve graph of the grating coefficient of coup and duty cycle relationship；
Fig. 3 is the structure diagram of unsymmetric structure phase-shifted grating in the application first embodiment；
Fig. 4 is the dimensional structure diagram of DFB semiconductor laser in the application second embodiment；
Fig. 5 is the side structure schematic view of DFB semiconductor laser in the application second embodiment.
Specific embodiment
The application is described in detail below with reference to specific embodiment shown in the drawings.But these embodiments are simultaneously
The application is not limited, structure that those of ordinary skill in the art are made according to these embodiments, method or functionally
Transformation is all contained in the protection domain of the application.
In each diagram of the application, for the ease of illustration, structure or partial certain sizes can be relative to other knots
Therefore structure or partial enlargement, are only used for the basic structure of the theme of diagram the application.
The term of the representation space relative position used herein such as "left", "right", " left side ", " right side " is for just
A unit as shown in the drawings or feature are described relative to another unit or the relationship of feature in the purpose of explanation.It is empty
Between the term of relative position can be intended to include different direction of the equipment in using or working other than orientation shown in figure.
If for example, the equipment in figure is overturn, other will be located at by being described as being located at the unit of other units or feature " right side "
Unit or feature " left side ".Therefore, exemplary term " right side " can include left side and both orientation of right side.Equipment can be with
Other modes are directed（It is rotated by 90 ° or other directions）, and correspondingly explain used herein and space correlation description.
Join shown in Fig. 1, introduce phase-shifted grating 10 ' of the prior art.The phase-shifted grating 10 ' is including being located in phase-shifted grating
The phase shift 11 ' of heart position and the first grating 12 ' and the second grating 13 ' positioned at phase shift both sides.
The first grating 12 ' and the second grating 13 ' are symmetrical arranged along phase shift 11 ' in the prior art, the first grating 12 ' and second
The length L of grating 13 '1And L2It is identical, etching depth H1And H2It is identical, periods lambda1And Λ2It is equal, duty ratio γ1And γ2It is constant
It is constant, and γ1And γ2It is equal.
Wherein, the duty ratio ratio shared in a cycle Λ for grating tooth width degree b, as shown in Figure 1, the first grating
12 ' duty ratio γ1=b1/Λ1, the duty ratio γ of the second grating 13 '2=b2/Λ2, wherein, grating tooth width degree b1=b2, periods lambda1
=Λ2, therefore, the duty ratio of the duty ratio of the first grating 12 ' and the second grating 13 ' is equal, i.e. γ1=γ2。
Fig. 2 show the curve graph of the grating coefficient of coup and duty cycle relationship, it can be seen that the coefficient of coup and duty ratio have
Correspondence, for pure index-coupled type DFB semiconductor laser, coefficient of coup κ is proportional to sin (π γ), wherein, κ
For the coefficient of coup of phase-shifted grating, the power of grating feedback is represented, γ is the duty ratio of phase-shifted grating.In identical etching depth
Under the conditions of, if the duty ratio γ of the first grating 12 ' and the second grating 13 '1And γ2It is equal, the first grating 12 ' and the second grating 13 '
Coefficient of coup κ1And κ2Also it is equal；In addition, under the conditions of identical etching depth, the first grating 12 ' and the second grating 13 '
Duty ratio γ1And γ2Meet γ1+γ2When=1, the coefficient of coup κ of the first grating 12 ' and the second grating 13 '1And κ2Also it is equal.
Based on the DFB semiconductor laser for using phase-shifted grating 10 ' in the prior art, at DFB semiconductor laser both ends
Face all coating anti reflection films（AR, reflectivity are less than 1%）Or not in the case of plated film, two end face Output optical power P1And P2Phase
Deng i.e. P2:P1=κ1: κ2=sin(πγ1): sin(πγ2).To realize DFB semiconductor laser Output optical power it is non-
Symmetrical structure, can be by plating highly reflecting films (HR) on laser end face, coating anti reflection film (AR) on another end face, such as background
Described in technology, laser mode hopping can be caused in this way.Or grating phase shift is deviateed into filters center position, it is biased to laser output
End then as described in the background art, can aggravate the influence of effects of spatial, reduce single mode yield in this way.
Join shown in Fig. 3, introduce the phase-shifted grating 10 in the application first embodiment.The phase-shifted grating 10 includes phase shift 11
And the first grating 12 and the second grating 13 positioned at 11 both sides of phase shift.Wherein, phase shift 11 is true phase shift, and phase-shift phase can be
0（Uniform grating）, λ/4, λ/8 or λ, or the phase-shift phase of other numerical value, wherein λ are the output wavelength of phase-shifted grating.This
In application, it is preferred that the phase-shift phase of the phase shift 11 is λ/4, so as to effectively eliminate bimodulus degeneracy.Phase shift light in the application
The phase shift 11 of grid is true phase shift, different from the equivalent phase shift in sampled-grating.Phase-shifted grating application based on true phase shift
When the DFB semiconductor laser of unsymmetric structure, coupling efficiency is than the sampled-grating application based on equivalent phase shift in laser cavity
Big in the coupling efficiency of the DFB semiconductor laser of unsymmetric structure, chamber length, the DFB semiconductor laser modulating performance is more
It is good.
The first grating 12 and the second grating 13 are located at 11 both sides of phase shift, the first grating 12 and second respectively in present embodiment
The length L of grating 131And L2Difference, and L1＞ L2.The 11 off-centered range of phase shift is about 0 to 30%, i.e., and described
The length of one grating 12 accounts for the 50% to 80% of grating total length.The etching depth H of first grating 12 and the second grating 131And H2Phase
Together, periods lambda1And Λ2It is equal.So as to improve the Output optical power of 13 one end of i.e. the second grating of output terminal.First grating
12 and second grating 13 include the apodization section grating of adjacent phase shift setting, and the duty ratio of the apodization section grating gradually becomes
Change so that the index modulation of the phase-shifted grating is gradually reduced by two lateral phase shifts.By the consecutive variations of grating duty ratio,
Apodization is introduced in grating at left and right sides of the phase shift in certain length, forms what index modulation was gradually reduced by two lateral phase shifts
Distribution.It by introducing apodization, can effectively weaken the influence of effects of spatial, while effective Output optical power is increased, carry
High single mode stability.Also, it is also avoided that the shortwave loss of grating after introducing apodization and effectively inhibits bragg grating
Reflectance spectrum, and the oscillation of chirped fiber grating delay character can be reduced.
Wherein, duty ratio is grating tooth width degree shared ratio in one cycle, periods lambda in present embodiment1=Λ2,
By designing the grating tooth width degree b in the first grating 12 and the second grating 131And b2, the duty ratio of grating is adjusted, if the
The grating tooth width degree b of one grating 121Invariable, the duty ratio for making the first grating is a steady state value, the second grating whole or portion
It is divided into apodization section grating, grating tooth width degree b2It is gradually changed along optical grating axial, the second grating is made by the design for introducing apodization
Duty ratio gradually changes, to weaken the influence of effects of spatial.
The length L of the apodization section gratingAAnd LBLess than the length L of the first grating 121.In the present embodiment, described
The length of the apodization section grating of one grating 12 and the second grating 13 is identical, i.e. LA=LB, and first grating, 12 and second grating
13 Refractive index modulation distribution of apodization section grating and duty ratio γ1、γ2Variation be consistent.Certainly, if first light
The length of the apodization section grating of 12 and second grating 13 of grid differs or the apodization section grating of the first grating 12 and the second grating 13
Duty ratio γ1And γ2Variation it is not consistent, also can reach the purpose of the present invention.
Specifically, 12 or second grating 13 of the first grating, which further includes, is set to apodization section grating away from 11 side of phase shift
Uniform segment grating.Due to the length L of the first grating 121More than the length L of the second grating 132If then second grating 13 is complete
Portion is apodization section grating, then is only provided with uniform segment grating on the first grating 12；It is cut if 13 top of the second grating is divided into
Toe section grating is then both provided with uniform segment grating on the first grating 12 and the second grating 13.
In present embodiment, the duty ratio γ of uniform segment grating3For a steady state value a, 0<a<1.0, on the first grating 12
The duty ratio γ of apodization section grating1And the duty ratio γ of the second apodization section grating on grating 131Gradually become along optical grating axial
Change.Wherein：
As the duty ratio γ of uniform segment grating3For a steady state value a, 0<a<When 0.5, the duty ratio of the apodization section grating is from phase shift
11 are gradually increased to a to both sides along optical grating axial by 0；
As the duty ratio γ of uniform segment grating3During for steady state value an a, a=0.5, the duty ratio of the apodization section grating is from phase shift 11
0.5 is gradually increased to by 0 or gradually decrease to 0.5 by 1.0 to both sides along optical grating axial；
As the duty ratio γ of uniform segment grating3For a steady state value a, 0.5<a<When 1, the duty ratio of the apodization section grating is from phase shift
To both sides along optical grating axial a is gradually decreased to by 1.0.
Since coefficient of coup κ is proportional to sin (π γ), wherein, κ is the coefficient of coup of phase-shifted grating, represents grating feedback
Power, γ are the duty ratio of phase-shifted grating, meanwhile, coefficient of coup κ is also proportional to the etching depth H of grating.In present embodiment
Under conditions of etching depth H is equal, the duty ratio γ of the first grating 121And second grating 13 duty ratio γ2Along optical grating axial
Gradually change, then the first grating 12, the second grating 13 apodization section grating coefficient of coup κ1、κ2It is gradually changed along optical grating axial,
The coefficient of coup κ of the apodization section grating of first grating 12 and the second grating 131And κ2Differ.Also, the first grating 12 and the second light
The coefficient of coup κ of the apodization section grating of grid 131And κ2Gradually increase from phase shift to both sides, so as to effectively weaken spatial hole burning
The influence of effect.And when the unsymmetric structure phase-shifted grating is applied in DFB semiconductor laser, in dfb semiconductor laser
Device both ends of the surface are plated with anti-reflective film（AR, reflectivity are less than 1%）Or not in the case of plated film, two end face Output optical power
P1And P2Differ.
Therefore, under conditions of etching depth is equal, the length L of the first grating of position 12 by designing phase shift1
With the length L of the second grating 132It is unequal, you can to realize the asymmetric output of luminous power, partly led using the DFB of the phase-shifted grating
The Output optical power that both ends then can be achieved in body laser is different.Meanwhile by being introduced in the first grating 12 and the second grating 13
Apodization so that the duty ratio of the first grating 12 and the second grating 13 gradually changes, and realize respectively along the direction away from phase shift 11
The coefficient of coup of 11 both sides grating of phase shift becomes larger along the direction away from phase shift 11, then can effectively weaken effects of spatial
Influence.
Preferably, phase shift 11 is more biased towards the output terminal of the second grating 12 and the length of the first grating 12 in present embodiment
L1More than the length L of the second grating 132, then the Output optical power P of 13 1 side end face of the second grating2More than 12 side of the first grating
The Output optical power P of end face1, i.e. P2:P1＞ 1.
Also, the duty ratio γ of uniform grating in present embodiment3For optimum taking air ratio 0.5, the apodization of the first grating 12
The duty ratio γ of section grating1And second grating 13 apodization section grating duty ratio γ2From phase shift 11 to both sides by 0 gradually increase
0.5 is gradually decreased to 0.5 or by 1.0, then the coefficient of coup κ of the first grating 121And second grating 13 coefficient of coup κ2Also certainly
Phase shift 11 gradually increases to both sides, to weaken the influence of effects of spatial.
Join shown in Fig. 3, Fig. 4, introduce DFB semiconductor laser 100 in second of embodiment of the application.The DFB is partly led
Body laser 100 include DFB laser cavities and several epitaxial layers above and below DFB laser cavities, DFB laser cavities include according to
Grating etching barrier layer 20, phase-shifted grating 10, the grating coating 30 of secondary setting, the interior grating for playing modeling of DFB laser cavities
It is phase-shifted grating 10, wherein, phase-shifted grating 10 is identical with the unsymmetric structure phase-shifted grating 10 in first embodiment, this
Place is no longer repeated.The length L of right side laser output, i.e. the second grating 13 is biased in phase shift 11 in phase-shifted grating 102It is more than
The length L of first grating 121, to realize the asymmetric output of the luminous power at 100 both ends of Distributed Feedback Laser, increase right side laser is defeated
The Output optical power of outlet.And introduce apodization in 11 both sides of phase shift so that the apodization of the first grating 12 and the second grating 13
The coefficient of coup of section grating becomes larger from phase shift to both sides, to weaken the influence of effects of spatial.
Formation of the DFB semiconductor laser 100 above and below DFB laser cavities has several epitaxial layers, such as this implementation
In mode, the epitaxial layer below DFB laser cavities includes substrate 31, buffer layer 32, lower limit layer 33, multiple quantum well layer 34 and the upper limit
Preparative layer 35, the epitaxial layer above DFB laser cavities include vallum etching barrier layer 41 and vallum layer 42.
The epitaxial material of epitaxial layer be III-V race's compound semiconductor material and IV-VI race's compound semiconductor material, such as
InGaAsP/InP, InAlGaAs/InP, AlGaAs/GaAs, InGaAs/InGaP, GaAsP/InGaP etc..
DFB semiconductor laser 100 is according only to the duty ratio for needing to design two sections of gratings of phase shift or so in present embodiment,
And the techniques such as 100 epitaxial structure of DFB semiconductor laser and electrode preparation are same as the prior art, below to present embodiment
In to preparing phase-shifted grating 10 with nano impression in DFB laser cavities the step of be described in detail.
Wherein, the making of phase-shifted grating 10 includes the following steps：
By one layer of nano impression glue of photoresist spinner spin coating on grating layer, the thickness of nano impression glue is according to the etching depth of grating need
It wants and determines, and by the rotating speed and time control of photoresist spinner；
Grating pattern on nano-imprint stamp is transferred on nano impression glue, is formed on nano impression glue and introduces above-mentioned cut
The asymmetric phase-shifted grating pattern of toe；
Nano-imprint stamp is sloughed, asymmetric phase-shifted grating structure described herein is formed on nano impression glue；
It is etched using ICP, the structure imprinted on glue is transferred to grating layer, the asymmetric phase shift light is formed on grating layer
Grid, so as to which phase-shifted grating 10 be made.
Next, the preparation process of DFB semiconductor laser in present embodiment 100 is described in detail.
Pass through MOCVD epitaxy technology, in 300 μm of N-shaped InP substrate 31, epitaxial growth successively：
Thickness 400nm, doping concentration 1.5 × 1018cm-2N-shaped InP as buffer layer 32；
The InGaAsP lower limit layers 33 of thickness 50nm；
InGaAsP multiple quantum well layers 34 are strained, multiple quantum well layer 34 includes 5 Quantum Well, potential well layer thickness in present embodiment
5nm ,+1.5% compressive strain, barrier layer thickness 10nm, -0.6% tensile strain, potential well layer and barrier layer alternating growth；
Thickness 40nm, doping concentration 2 × 1017cm-2P-type InGaAsP upper limiting layers 35；
Thickness 25nm, doping concentration 2 × 1017cm-2P-type InP gratings etching barrier layer 20；
The p-type InGaAsP phase-shifted gratings 10 of thickness 50nm, the making of the phase-shifted grating 10 are as described above；
Thickness 90nm, doping concentration 3 × 1017cm-2P-type InP gratings coating 30；
The p-type InGaAsP vallums etching barrier layer 41 of thickness 25nm；
1.6 μm of thickness, doping concentration 3 × 1017cm-2P-type InP vallums layer 42.
In above-mentioned 100 both ends of the surface of DFB semiconductor laser all coating anti reflection films（AR, reflectivity are less than 1%）In the case of,
Two end face Output optical power P1And P2It differs, you can realize the asymmetry of Output optical power, increase DFB semiconductor laser 100
Effective Output optical power.
Further, InGaAsP ohmic contact layers 43 and p-type electricity can also be further formed in the top of vallum layer 42
Pole 44, preparation process is same as the prior art, is no longer described in detail herein.
DFB semiconductor laser 100 in present embodiment is illustrated by taking ridge waveguide structure as an example, in other implementations
Buried heterostructure type structure can also be designed in mode, no longer citing is described in detail herein.
It should be understood that it is applied in the above embodiment with the unsymmetric structure phase-shifted grating based on apodization section grating
It is illustrated for DFB semiconductor laser 100, such DFB semiconductor laser 100 can carry out plated film in both ends of the surface.
Photon integrated chip in other embodiment, such as detector array, laser array, modulator array and multiplexer photon
Device, such photonic device is prepared by selection region growth technology or docking growing technology, in integrating process,
Effective Output optical power can not be increased, therefore the position of phase shift is changed simultaneously by the application by plating highly reflecting films or anti-reflective film
Apodization is introduced, then asymmetric phase-shifted grating can be applied in highly integrated photon integrated chip, effective to improve end face
Output optical power.
DFB semiconductor laser 100 of the application based on unsymmetric structure phase-shifted grating, the grating in phase shift both sides etch
Under conditions of depth and screen periods are constant, the position for changing phase shift causes the length of the first grating to be more than the second grating so that
DFB semiconductor laser 100 can realize the asymmetry of Output optical power, increase effective Output optical power of laser.And
Apodization section grating is introduced in the first grating and the second grating so that the coefficient of coup gradually increases along the direction away from phase shift, has
Effect weakens the influence of effects of spatial.By the selection of phase shift position, uniform segment grating in the first grating and the second grating
The apodization journey of the selection of duty ratio, the ratio between the length of optimization design apodization section grating and entire grating length and apodization section grating
Degree realizes the both ends of the surface Output optical power P of different numerical value1And P2The ratio between.
The application is had the advantages that by the above embodiment：
Unsymmetric structure phase-shifted grating based on apodization section grating is applied to single DFB semiconductor laser 100, is not plated in end face
Film or in the case of being coated with anti-reflective film, increases effective Output optical power of laser, improves DFB semiconductor laser 100
Efficiency, reduce the influence of effects of spatial, improve the stability of DFB semiconductor laser 100；
Unsymmetric structure phase-shifted grating and DFB semiconductor laser 100 based on apodization section grating can be applied to highly integrated
In photon integrated chip, effective Output optical power of photon integrated chip end face is improved.
It should be appreciated that although this specification is described in terms of embodiments, but not each embodiment only includes one
A independent technical solution, this description of the specification is merely for the sake of clarity, and those skilled in the art should will say
For bright book as an entirety, the technical solution in each embodiment may also be suitably combined to form those skilled in the art can
With the other embodiment of understanding.
Those listed above it is a series of be described in detail only for the application feasibility embodiment specifically
Bright, they are not limiting the protection domain of the application, all equivalent implementations made without departing from the application skill spirit
Or change should be included within the protection domain of the application.
Claims (8)
1. a kind of asymmetric phase-shifted grating, which is characterized in that the phase-shifted grating include phase shift and positioned at phase shift both sides first
Grating and the second grating, the length of first grating are more than the etching depth of the second grating, first grating and the second grating
It is equal to spend identical and screen periods；First grating and the second grating include the apodization section grating of adjacent phase shift setting, and
And the duty ratio of the apodization section grating gradually changes so that the index modulation of the phase-shifted grating is gradual by two lateral phase shifts
Reduce.
2. asymmetric phase-shifted grating according to claim 1, which is characterized in that first grating and the second grating are cut
The length of toe section grating is identical and Refractive index modulation distribution is consistent.
3. asymmetric phase-shifted grating according to claim 1, which is characterized in that first grating or the second grating also wrap
It includes and is set to the uniform segment grating that apodization section grating deviates from phase shift side, the duty ratio of the uniform segment grating is a steady state value
A, 0<a<1.0, wherein：
When the duty ratio of uniform segment grating is a steady state value a, 0<a<When 0.5, the duty ratio of the apodization section grating from phase shift to
Both sides are gradually increased to a along optical grating axial by 0；
When the duty ratio of uniform segment grating is steady state value an a, a=0.5, the duty ratio of the apodization section grating is from phase shift to two
Side is gradually increased to 0.5 by 0 along optical grating axial or gradually decreases to 0.5 by 1.0；
When the duty ratio of uniform segment grating is a steady state value a, 0.5<a<When 1, the duty ratio of the apodization section grating from phase shift to
Both sides gradually decrease to a along optical grating axial by 1.0.
4. a kind of DFB semiconductor laser, the DFB semiconductor laser includes DFB laser cavities and above DFB laser cavity
With several epitaxial layers of lower section, DFB laser cavities include the grating etching barrier layer, phase-shifted grating, the grating coating that set gradually,
It is characterized in that, the phase-shifted grating include phase shift and the first grating and the second grating positioned at phase shift both sides, the first grating and
The etching depth of second grating is identical and screen periods are equal, and the length of first grating is more than the second grating；Described first
Grating and the second grating include the apodization section grating of adjacent phase shift setting, and the duty ratio of the apodization section grating gradually becomes
Change so that the index modulation of the phase-shifted grating is gradually reduced by two lateral phase shifts.
5. DFB semiconductor laser according to claim 4, which is characterized in that first grating and the second grating
The length of apodization section grating is identical and Refractive index modulation distribution is consistent.
6. DFB semiconductor laser according to claim 4, which is characterized in that first grating or the second grating are also
Include and be set to the uniform segment grating that apodization section grating deviates from phase shift side, the duty ratio of the uniform segment grating is constant for one
Value a, 0<a<1.0, wherein：
When the duty ratio of uniform segment grating is a steady state value a, 0<a<When 0.5, the duty ratio of the apodization section grating from phase shift to
Both sides are gradually increased to a along optical grating axial by 0；
When the duty ratio of uniform segment grating is steady state value an a, a=0.5, the duty ratio of the apodization section grating is from phase shift to two
Side is gradually increased to 0.5 by 0 along optical grating axial or gradually decreases to 0.5 by 1.0；
When the duty ratio of uniform segment grating is a steady state value a, 0.5<a<When 1.0, the duty ratio of the apodization section grating is from phase shift
To both sides along optical grating axial a is gradually decreased to by 1.0.
7. DFB semiconductor laser according to claim 4, which is characterized in that the both sides of the DFB semiconductor laser
End face is coated with anti-reflective film.
8. DFB semiconductor laser according to claim 4, which is characterized in that the DFB semiconductor laser is buries
Heterojunction type laser or ridge waveguide lasers.
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|---|---|---|---|---|
| CN103337788A (en) * | 2013-04-24 | 2013-10-02 | 南京大学 | DFB semiconductor laser based on asymmetric structure of reconstruction-equivalent chirp and preparation method thereof |
| CN103762500A (en) * | 2013-11-27 | 2014-04-30 | 南京大学 | Asymmetric equivalent apodization sampling optical grating and laser based on reconstruction-equivalent chirp |
| CN104917051A (en) * | 2015-05-29 | 2015-09-16 | 江苏微宁科技有限公司 | Distributed coupling coefficient DFB laser based on reconstruction-equivalent chirp technology and array thereof |
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2016
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|---|---|---|---|---|
| CN103337788A (en) * | 2013-04-24 | 2013-10-02 | 南京大学 | DFB semiconductor laser based on asymmetric structure of reconstruction-equivalent chirp and preparation method thereof |
| CN103762500A (en) * | 2013-11-27 | 2014-04-30 | 南京大学 | Asymmetric equivalent apodization sampling optical grating and laser based on reconstruction-equivalent chirp |
| CN104917051A (en) * | 2015-05-29 | 2015-09-16 | 江苏微宁科技有限公司 | Distributed coupling coefficient DFB laser based on reconstruction-equivalent chirp technology and array thereof |
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