CN102916340B - Phase-shift electric-control sampling grating semiconductor laser and setting method therefor - Google Patents
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Abstract
The invention proposes a phase-shift electric-control sampling grating semiconductor laser. A DFB (distributed feed back) semiconductor laser consists of a first sampling grating area, a second sampling grating area and a phase-shift area, wherein gratings in the two sampling grating areas are sampling bragg gratings (SBG), the phase-shift area is positioned in the middle, and the sampling period is 1-10 micrometers; electrodes of the two sampling grating areas are connected together and are isolated from an electrode of the phase-shift area; the effective refractive index and the length of the sampling grating areas are expressed by nSBG and nP, and the effective refractive index and the length of the phase-shift area are expressed by LSBG and LP; and the primary control on the hot-shot wavelength of the laser can be realized only by changing the sampling period P, so as to form the phase-shift electric-control SBG DFB semiconductor laser.
Description
Technical field
The invention belongs to photoelectron technical field, relate to optical fiber communication, integreted phontonics, photoelectric sensing and other optoelectronic information process; A kind of wavelength continuously adjustable sampling grating semiconductor laser and method to set up within the specific limits.
Background technology
Due to present to the demand sharp increase of optical communication network transmission capacity, dense wave division multipurpose (Dense wavelength division multiplexing, WDM) number of channel of system multiplexing gets more and more, and this communication system needs the laser light source with different excitation wavelength.Sharply to rise problem for reducing the energy consumption brought thus and maintenance cost, be inevitable integreted phontonics (Photonic integration circuit, PIC) selection.But high-performance light sources---the laser array used in the pic chip of current this large-scale integrated, can only depend on high-precision electronic bundle inscription technology and manufacture.For the true phase-shifted grating meeting ITU-T standard wave length, this electron beam inscribes the machining accuracy that technology needs more than at least 0.1 nanometer scale, can only adopt and process through improved especially electron beam exposure apparatus, its processing technology is slowly time-consuming, processing cost is very high, and the large-scale commercial that can not be used for laser is produced.
In addition, the excitation wavelength of ITU-T standard to laser proposes strict requirement, and in the semiconductor laser manufacturing process of reality, there is various accidentalia and make laser excitation wavelength depart from this requirement.Thus, when making multi-wavelength laser array, the normal wave length tuning device that adopts is as thermal tuning or mode such as change Injection Current and multi-electrode injection etc., and the excitation wavelength controlling laser strictly aims at ITU-T standard.These wave length tuning devices make the structure of laser become complicated, and difficulty of processing increases, and they also can cause the unbalanced problem of each laser Output of laser power in multi-wavelength laser array.
For the preliminary control of laser excitation wavelength, old reconstruction-equivalent chirp (Reconstruction-equivalent chirp, the REC) technology to flying teaching inventive of Nanjing University has very large advantage.Utilize this sampled-grating technology, the wavelength control that script can be replaced to need nanometer scale technique to realize by micron dimension processing technology, cost of manufacture has substantial degradation, and is particularly suitable for making the multi-wavelength semiconductor laser array in PIC equipment.For the meticulous adjustment of laser excitation wavelength, T. the method introducing phase-shifted region in the middle of Distributed Feedback Laser that the people such as Numai proposes then has very large advantage, Experimental report display, by changing the size injecting phase-shifted region electric current, can regulate laser excitation wavelength to reach 2.1nm continuously.Our theoretical research shows, under existing process conditions, the excitation wavelength continuous tuning range of this laser can up to 5 ~ 6nm.The advantage of this laser is in the process regulated continuously at excitation wavelength, the laser power variation exported when the thresholding electric current of laser and running current (twice is to three times of thresholding electric currents) is little, and its deficiency is difficult to make multi-wavelength laser array in this way.
Leading reference
[1] Tingye, L., Advances in optical fiber communications: an historical perspective. IEEE Journal on Selected Areas in Communications, 1983. 1(3): 356-371.
[2] Ishio, H., J. Minowa, and K. Nosu, Review and status of wavelength-division-multiplexing technology and its application. Journal of Lightwave Technology, 1984. 2(4): 448-463.
[3] Keiser, G.E., A Review of WDM Technology and Applications. Optical Fiber Technology, 1999. 5: p. 37.
[4] Chen, X.F., et al., Photonic integrated technology for multi-wavelength laser emission. Chinese Science Bulletin, 2011. 56(28-29): 3064-3071.
[5] Tennant, D. and T. Koch, Fabrication and uniformity issues in λ/4 shifted DFB laser arrays using e-beam generated contact grating masks. Microelectronic Engineering, 1996. 32(1-4): 331-341.
[6] Steingr¨ ber, R., et al., Continuously chirped gratings for DFB-lasers fabricated by direct write electron-beam lithography. Microelectronic Engineering, 2002. 61-62: 331-335.
[7] Sakano, S., et al., Tunable DFB laser with a striped thin-film heater. IEEE Photonics Technology Letters, 1992. 4(4): 321-323.
[8] Hansmann, S., et al., Static and Dynamic Properties of InGaAsP-InP Distributed-Feedback Lasers—a Detailed Comparison between Experiment and Theory. IEEE Journal of Quantum Electronics, 1994. 30(11): 2477-2484.
[9] Dutta, N., et al., Electronically tunable distributed feedback lasers. Applied Physics Letters, 1986. 48(22): 1501-1503.
[10] Dai, Y., et al., Sampled Bragg grating with desired response in one channel by use of a reconstruction algorithm and equivalent chirp. Optics Letters, 2004. 29(12): 1333－1335.
[11] Chen, X., et al., Analytical expression of sampled Bragg gratings with chirp in the sampling period and its application in dispersion management design in a WDM system. IEEE Photonics Technology Letters, 2000. 12(8): 1013－1015.
[12] Feng, J., et al., A novel method to achieve various equivalent chirp profiles in sampled Bragg gratings using uniform-period phase masks. Optics Communications, 2002. 205: 71-75.
[13] Dai, Y., et al., Equivalent phase shift in a fiber Bragg grating achieved by changing the sampling period. IEEE Photonics Technology Letters, 2004. 16(10): 2284-2296.
[14] Numai, T., 1.5 μm phase-controlled distributed feedback wavelength tunable optical filter. IEEE Journal of Quantum Electronics, 1992. 28(6): 1513-1519.
[15] H. Ghafouri-Shiraz, et al., Analysis of a λ/4-Phase-Shifted Double Phase-Shift-Controlled Distributed Feedback Wavelength Tunable Optical Filter. IEEE Journal of Quantum Electronics, 1997. 33(4): 556-561.
[16] Y. KOTAKI, et al., Tunable, narrow-linewidth and high-power lambda 4-shifted DFB laser. Electronics Letters, 1989. 25(15): 990-992.
[17] Nobuhiro Nunoya, et al. Novel tunable DFB laser with separated high coupling coefficient gratings. in 2006 International Conference on Indium Phosphide and Related Materials Conference. 2006: 68-71。
Summary of the invention
The object of the invention is to, ITU-T standard is met for making the excitation wavelength of semiconductor laser, propose a kind of sampled-grating technology that utilizes to carry out the preliminary control of noise spectra of semiconductor lasers excitation wavelength, then by changing the method for laser two sampled grating area and middle phase-shifted region Injection Current size, obtain different phase-shift value, and then the method for meticulous adjustment laser excitation wavelength and device, be manufacturing and designing of DFB semiconductor laser, propose a kind of new Structure and energy.
The object of the invention is to propose adjustable sampling grating semiconductor laser of a kind of excitation wavelength and preparation method thereof, sampled-grating technology is utilized to be provided with two sampled grating area, in the middle of two sampled grating area, be provided with a phase-shifted region form sampled-grating laser, inject control technology based on sampled-grating technology and phase shifted current and obtain wavelengthtunable distributed feedback (DFB) semiconductor laser and manufacture method.
Technical solution of the present invention is: based on the sampling grating semiconductor laser of phase shift electric control, and the DFB semiconductor laser structure described in it is made up of two sampled grating area and a phase-shifted region.Grating in sampled grating area, both sides is sampling Bragg grating (Sampled Bragg grating, SBG), middle phase-shifted region can not have grating, maybe can there is the SBG identical with sampled grating area, sampling period is from 1 micron to some tens of pm magnitude, the Electrode connection of two sampled grating area is together, but isolated with the electrode of phase-shifted region.
Usually one of sampled-grating the ± 1 grade of sub-gratings is selected to penetrate channel as swashing; In addition, swash to penetrate and zero level channel does not occur to swash and penetrates for ensureing to only have selected sharp channel of penetrating, when selecting to make the semi-conducting material of laser, the center, gain region of semi-conducting material being arranged on and selected sharply penetrating channel bragg wavelength place and away from zero level channel bragg wavelength.
1, common uniform sampling grating
Fig. 1 is the schematic diagram of common uniform sampling template, and wherein a is the length having grating part in the sampling period, and P is the sampling period.Mathematically, the index modulation of a sampling Bragg grating
can be expressed as
(1)
Here,
with
refractive index modulation depth and the screen periods of seed grating respectively,
represent complex conjugate.Shan in Fig. 1
, according to Fourier analysis, can be represented by the formula
(2)
The m level Fourier coefficient of sampled-grating
can be expressed as
(3)
Wushu (2) and (3) substitute into formula (1), can obtain
(4)
From formula (4), a sampled-grating can regard the superposition of many shadow gratings (a shadow grating pair answers a channel) as.The cycle of m level shadow grating
can be expressed as
(5)
Therefore in m level shadow grating, bragg wavelength
can be expressed as
(6)
for effective refractive index.Sampling duty ratio
be defined as the length of uniform grating and the ratio of sampling period, be also
(7)
If the form of sampling is periodic square wave, according to the result of theory calculate above, namely formula (1) is known to (4), in any one-level sub-gratings except 0 grade of a sampled-grating, index modulation intensity in the ± 1 grade of sub-gratings is maximum, so when making Distributed Feedback Laser by sampled-grating structure, one of the ± 1 grade of sub-gratings is usually selected to penetrate channel as swashing.In sampled-grating the ± 1 grade of sub-gratings, index modulation intensity
with the pass of sampling duty ratio be
（8）
The relation of index modulation intensity and sampling duty ratio in ± 1 grade of sub-gratings, as shown in Figure 2.From formula (8) and the known duty ratio of Fig. 2
when=0.5, in the ± 1 grade of sub-gratings, index modulation intensity is maximum, the strongest to the feedback effect of the ± 1 grade of sub-gratings bragg wavelength.Duty ratio
depart from more than 0.5, in the ± 1 grade of sub-gratings, index modulation intensity is less, then more weak to the feedback effect of the ± 1 grade of sub-gratings bragg wavelength.
For the-1 grade of sub-gratings, formula (5) and (6) are changed to
(9)
(10)
For common uniform grating, its bragg wavelength
can be expressed as
(11)
As can be seen from formula (9) to (11), similarly control the size of bragg wavelength, need to change screen periods in common uniform grating
size, as long as and change the size of sampling period P in sampled-grating.In semiconductor laser, the former is approximately nanometer more than 200, and the latter is several microns and arrives some tens of pm, the latter's one to two orders of magnitude larger than the former.Therefore control the size of bragg wavelength equally, utilize sampled-grating (with its ± 1 grade of sub-gratings) come much easier than with uniform grating.
2, phase shift electric control method
The structure of phase shift electric control sampled-grating laser device, schematically can be represented by Fig. 3.Its design feature is described below: the grating in the sampled grating area on both sides is sampling Bragg grating (Sampled Bragg grating, SBG), and middle phase-shifted region does not have grating, can have the SBG identical with sampled grating area yet.The Electrode connection of sampled grating area is together, but isolated with the electrode of phase-shifted region.The effective refractive index of sampled grating area and phase-shifted region and length, use respectively
with
,
with
represent.
The gain center of active layer be arranged on sampled-grating ± bragg wavelength of one of 1 grade of sub-gratings
place's (usually selecting at the bragg wavelength place of-1 grade of sub-gratings, so illustrate for-1 grade of sub-gratings here), has
（12）
When different current density is injected in sampled grating area and phase-shifted region, due to the plasma effect of free carrier,
with
by difference, thus at phase-shifted region by generation phase shift
, size is
（13）
From formula (10), when seed light grid cycle remains unchanged, as long as change the sampling period
psize, just can realize the preliminary control to laser excitation wavelength.
In the sampling period
pwhen determining, in sampled grating area, phase-shifted region Injection Current
,
sum, namely laser works electric current (
+
) under the condition that remains unchanged, by formula (13) known change
with
ratio just can change the size introducing phase shift, the numerical value of any adjustment excitation wavelength in energy gap (the being generally 2 ~ 5nm) scope of sampled-grating ± 1 grade sub-gratings.For reducing the crosstalk between sampled grating area, phase-shifted region Injection Current, improving the effect changing and introduce phase shift meticulous adjustment laser excitation wavelength, between sampled grating area and phase-shifted region, electric isolution can also be carried out with He isotopic geochemistry.In introducing phase shift size within the scope of 0.25 π ~ 1.75 π, laser thresholding electric current and the laser power variation that laser exports when normal work (operating current is at 2 ~ 3 times of thresholding electric currents) very little.
Phase shift in the present invention owing to being distributed on whole phase-shifted region, because of but the phase shift of gradual change accumulation, hole burning effect common in phase shifted laser can be suppressed better compared with the phase shift of sudden change.
The second is based on the sampling grating semiconductor laser of phase shift electric control, and its structure is identical with above-mentioned DFB semiconductor laser basic structure with feature.Difference is that the sampling duty ratio of the sampled grating area that two length is identical is different, the sampling duty ratio of front portion
be 0.5, latter part of sampling duty ratio
it is the optimization value between 0.2 to 0.5.
From formula (8) and the known duty ratio of Fig. 2
when=0.5, in the ± 1 grade of sub-gratings, index modulation intensity is maximum, the strongest to the feedback effect of the ± 1 grade of sub-gratings bragg wavelength.Duty ratio
depart from more than 0.5, then in the ± 1 grade of sub-gratings, index modulation intensity is less, more weak to the feedback effect of the ± 1 grade of sub-gratings bragg wavelength.
Therefore, when swash penetrate power certain, latter part of sampling duty ratio
depart from more than 0.5, the laser power effectively exported from this sampled grating area, side is larger.When end face coating cannot be carried out, optimize latter part of sampling duty ratio
, the laser power that laser effectively exports from this side end face, sampled grating area one can be improved.
The third is based on the sampling grating semiconductor laser of phase shift electric control, and its structure is identical with described DFB semiconductor laser basic structure with feature.Difference is that the length of the sampled grating area that two sampled-gratings are identical is different.
When the sampled-grating of laser sampled grating area is identical, the longer feedback effect to excitation wavelength of sampled-grating section length is stronger.When the sampled grating area length stays constant of laser side of the present invention, opposite side sampled-grating section length is less then larger from the laser power of this side outgoing.
Therefore, when swash penetrate power certain and end face coating cannot be carried out, optimize the length of this laser two sampled grating area, just can improve the laser power that laser effectively exports from side, length shorter sampled grating area.
Above-mentioned three kinds of sampling grating semiconductor lasers based on phase shift electric control are unit lasers, can form single chip integrated phase shift electric control sampling grating semiconductor laser array.
The laser array be made up of such semiconductor laser,, working temperature identical at operating current is identical, the thresholding electric current of each laser and Output of laser power can keep roughly equal, and this brings very large convenience to the lasing modulation of laser array, coupling and transmission.
Above-mentioned three kinds of sampling grating semiconductor laser arrays based on phase shift electric control form PIC transmitting chip module, it is by the sampling grating semiconductor laser array of laser monitoring device array, phase shift electric control, modulator array (note: do not need modulator array during directly modulation), power equalizer array and multiplexer, by selection area epitaxial growth or docking growing technology, growth is integrated into and same epitaxial wafer obtains successively.
The invention has the beneficial effects as follows: sampled-grating combine with technique electrical pumping controls to introduce phase shift, can control the excitation wavelength of laser neatly, and make the performance that laser keeps superior.Sampled-grating technology is utilized with the control of the sampling period of large one to two orders of magnitude of contrast seed light grid cycle, can effectively to realize the basic controlling to laser excitation wavelength.To the excitation wavelength deviation that uncontrollable factor in chip of laser Material growth process causes, then control to introduce phase shift size by electrical pumping and carry out meticulous adjustment.In the sizeable situation of introducing phase shift, as when 0.25 π ~ 1.75 π, both ensure that single mode laser swashed the realization of penetrating, and also made the sampled-grating laser of structural similarity (being only that the sampling period is different with introducing phase shift) have close thresholding and swash and penetrate characteristic.The laser array be made up of such semiconductor laser, when introducing that phase shift size is not within the scope of 0.25 π ~ 1.75 π, operating current is identical, working temperature is identical, the Output of laser power of each laser can keep roughly equal, and this brings very large convenience to the lasing modulation of laser array, coupling and transmission.Semiconductor laser array in the present invention, has an enormous advantage in the development of PIC transmitting chip module.In wavelength continuous tuning range, the thresholding electric current of unit laser changes hardly, and the laser power exported under identical operating current also changes not quite, and thus this multi-wavelength laser array has superior transmission, modulation and coupled characteristic.In addition, make use of sampled-grating technology, have substantial degradation to the requirement of machining accuracy, thus this multi-wavelength laser array has lower manufacturing cost.
Accompanying drawing explanation
The sampling template schematic diagram of Fig. 1, uniform sampling grating.
The relation of the index modulation intensity in Fig. 2, ± 1 grade of sub-gratings and sampling duty ratio.
Fig. 3, phase shift electric control sampled-grating laser structure schematic diagram.
Fig. 4, phase shift electric control sampled-grating laser sampling template schematic diagram.
Fig. 5, two ultraviolet light beam interfere through sampling template and make sampled-grating schematic diagram.
Specific implementation method:
1, obtain the key of phase shift electric control sampling grating semiconductor laser in the present invention, be the making of sampled-grating structure, concrete method is
First, on grating mask plate, design and sampling tessellation required for making.As shown in Figure 4, the feature of sampling tessellation is: the sampled-grating along whole laser structure is all sampling period identical uniform sampling grating, but the phase-shifted region in the middle of sampled grating area, can be the sampled-grating identical with sampled grating area, also can be do not have grating.
Then with the ultraviolet light beam that two bundles are relevant, through the laggard row two-beam interference of sampling template, two-beam interference pattern and sampling tessellation are transcribed on photoresist simultaneously, as shown in Figure 5.1:n-InP substrate 2:n-InP resilient coating 3: lower limit layer 4: multiple quantum well active layer 5: upper limiting layer 6:U-InP+1.3 μm of InGaAsP layer (for making SBG grating) 7: photoresist 8: sampling template.
2, the structure of phase shift electric control sampling grating semiconductor laser
Phase shift electric control sampling grating semiconductor laser device, from bottom to up successively: n-electrode, N-shaped InP-base bottom material, extension N-shaped InP resilient coating, undoped Lattice Matching InGaAsP lower limit layer, strain InGaAsP multiple quantum well active layer, undoped Lattice Matching InGaAsP upper limiting layer, sampled-grating layer, the p-type InP layer of secondary epitaxy growth, the ohmic contact layer of p-type InGaAs and p-electrode.
The making of the phase shift electric control sampling grating semiconductor laser 3, in the present invention
Below with operation wavelength in 1550nm scope, the manufacturing process of phase shift electric control sampling grating semiconductor laser, illustrates laser of the present invention and comprises the concrete manufacture method of photo emissions module chip of this laser array.
(1) making of grating mask plate: according to prior design, uses common microelectronic technique to make sampling tessellation mask plate.
(2) phase shift electric control sampling grating semiconductor laser, carries out secondary epitaxy growth by metal-organic chemical vapor deposition method (Metal-organic chemical vapor deposition, MOCVD) technology and has carried out making.Its details is described below: first once extension N-shaped InP resilient coating (thickness 200nm, doping content about 1.1 ' 10 on N-shaped InP substrate material
18cm
-2), undoped Lattice Matching InGaAsP lower limit layer that 100nm is thick, strain InGaAsP Multiple Quantum Well (light wavelength of fluorescence 1.52 microns, 7 quantum well: the thick 8nm of trap, 0.5% compressive strain, build thick 10nm, lattice matched materials) and the thick p-type Lattice Matching InGaAsP(doping content about 1.1 ' 10 of 100nm
17cm
-3) upper limiting layer.Next by designed sampling optical mask plate, by the method that typical exposure exposes in conjunction with double-beam holographic interference, sampled-grating design transfer on the photoresist on upper limiting layer, then impose material etch, form required asymmetric sampling grating structure on upper limiting layer top.After preparing grating is good, then by secondary epitaxy growth p-type InP layer (thickness 1700nm, doping content about 1.1 ' 10
18cm
-2) and p-type InGaAs (thickness 100nm, doping content is greater than 1 ' 10
19cm
-2) ohmic contact layer.After epitaxial growth terminates, utilize common photoetching in conjunction with selective wet chemical etching, complete the making of ridge waveguide, ridge waveguide length is generally hundreds of micron dimension, and ridge is wide 2 microns, and ridge lateral sulcus is wide 20 microns, dark 1.5 microns.And then with plasma enhanced chemical vapor deposition method (Plasma-Enhanced Chemical Vapor Deposition, PECVD), around ridge waveguide, deposit the SiO that one deck 300nm is thick
2layer or organic substance BCB insulating barrier.Then utilize photoetching and selective wet chemical etching again, remove the SiO above laser ridge
2layer or organic substance BCB insulating barrier, expose its InGaAs ohmic contact layer; Use the method for magnetron sputtering again, above whole laser structure, plate the Au that thick Ti and 400nm of 100nm is thick respectively, in conjunction with photoetching process and selective wet chemical etching, the ohmic contact layer exposing InGaAs above vallum forms Ti-Au metal P electrode.In addition, after whole laser wafer is thinned to 150 μm, the Au-Ge-Ni(Au:Ge:Ni component ratio that 500nm is thick on the below evaporation of base material is 84:14:2) alloy is as n-electrode.Whether phase-shifted region has grating both of these case to be all exist, but from the impact of performance of laser, and effect when not having a grating also very well or better.
(3) based on the making of the photo emissions module chip of semiconductor laser array of the present invention
Laser monitoring device array, the multi-wavelength laser array, modulator array, power equalizer array and the multiplexer that form based on semiconductor laser of the present invention, by selection area epitaxial growth or docking growing technology, growth is integrated on same epitaxial wafer successively, just can make integrated photo emissions module chip.By design make laser in laser monitoring device array side sampled-grating sampling duty ratio be 0.5, modulator array side sampled-grating sampling duty ratio be not equal to 0.5 optimization calculated value.Or make laser be greater than modulator array side sampled-grating section length in the sampled-grating section length of laser monitoring device array side, sampled-grating section length gets the optimization calculated value of needs.Under the prerequisite that these two kinds of methods can make photo emissions module chip obtain at monitor array and certain sharply penetrate power, ensure normal work, make more swash penetrate power and export from modulator array direction.
For keeping the unimodular property of laser, actual in use process of the present invention, by select to do to swash penetrate channel ± design of one of 1 grade of channel at the center, gain region of semi-conducting material, thus makes 0 grade of main limit mould away from gain region.
Claims (9)
1., based on a sampling grating semiconductor laser for phase shift electric control, it is characterized in that the DFB semiconductor laser structure adopted is made up of first and second two sampled grating area and a phase-shifted region; Grating in sampled grating area, both sides is sampling Bragg grating SBG, and centre is phase-shifted region, and the sampling period is from 1 micron to some tens of pm magnitude; The Electrode connection of two sampled grating area is together, but isolated with the electrode of phase-shifted region; Index modulation intensity in uniform sampling grating, is expressed as
Know from formula (4), sampled-grating is equivalent to the superposition of many shadow gratings, a shadow grating pair answers a channel; The cycle of m level shadow grating is expressed as
Therefore, in m level shadow grating, bragg wavelength is expressed as
N
efffor effective refractive index, sampling duty ratio γ is defined as the length of uniform grating and the ratio of sampling period, namely
In any one-level sub-gratings except 0 grade of a sampled-grating, the index modulation intensity in the ± 1 grade of sub-gratings is maximum, so when making Distributed Feedback Laser by sampled-grating structure, selects one of the ± 1 grade of sub-gratings to penetrate channel as swashing; In sampled-grating the ± 1 grade of sub-gratings, index modulation intensity Δ n
± 1with the pass of sampling duty ratio be
For the-1 grade of sub-gratings, formula (5) and (6) are changed to
The effective refractive index of sampled grating area and phase-shifted region and length, use n respectively
sBGand n
p, L
sBGand L
prepresent; The gain center of laser active layer be arranged on sampled-grating ± bragg wavelengths of one of 1 grade of sub-gratings
bplace
When different current density is injected in sampled grating area and phase-shifted region, due to the plasma effect of free carrier, n
sBGand n
pby difference, thus at phase-shifted region by generation phase shift theta, size is
From formula (10), when shadow screen periods remains unchanged, as long as change the size of sampling period P, just can realize the preliminary control to laser excitation wavelength;
When the sampling period, P determined, in sampled grating area, phase-shifted region Injection Current I
s, I
psum, i.e. laser works electric current (I
s+ I
p) under the condition that remains unchanged, by formula (13) known change I
sand I
pratio just can change the size introducing phase shift, sampled-grating ± 1 grade sub-gratings energy gap, be generally 2 ~ 5nm scope in the numerical value of any adjustment excitation wavelength;
Wherein Δ n
sand Λ
0be refractive index modulation depth and the screen periods of seed grating respectively, c.c. represents complex conjugate, F
mbe the m level Fourier coefficient of sampled-grating, a is the length having grating part in the sampling period, and P is the sampling period.
2., according to the sampling grating semiconductor laser of claim 1 based on phase shift electric control, it is characterized in that selecting one of sampled-grating the ± 1 grade of sub-gratings to penetrate channel as swashing; The center, gain region of semi-conducting material is arranged on and selected sharply penetrates channel bragg wavelength place and away from zero level channel bragg wavelength.
3., according to the sampling grating semiconductor laser of claim 2 based on phase shift electric control, it is characterized in that the sampling duty ratio of the sampled grating area that two length is identical is different, the sampling duty ratio γ of the first sampled-grating
lbe the sampling duty ratio γ of the 0.5, second sampled-grating
rit is the value between 0.2 to 0.5.
4. the sampling grating semiconductor laser based on phase shift electric control according to one of 1-3 of claim, is characterized in that forming DFB semiconductor laser single-chip integration array by described phase shift electric control sampling grating semiconductor laser.
5. the sampling grating semiconductor laser based on phase shift electric control according to claim 4, it is characterized in that the PIC transmitting chip module that laser single-chip integration array is formed, by laser monitoring device array, the described sampling grating semiconductor laser single-chip integration array based on phase shift electric control, modulator array, power equalizer array and multiplexer, be integrated on same epitaxial wafer by selection area epitaxial growth or docking growth.
6. the sampling grating semiconductor laser based on phase shift electric control according to 1 of claim, when it is characterized in that duty ratio is 0.5, in the ± 1 grade of sub-gratings, index modulation intensity is maximum, the strongest to the feedback effect of the ± 1 grade of sub-gratings bragg wavelength; Duty ratio departs from more than 0.5, then in the ± 1 grade of sub-gratings, index modulation intensity is less, more weak to the feedback effect of the ± 1 grade of sub-gratings bragg wavelength.
7. the sampling grating semiconductor laser based on phase shift electric control according to 3 of claim, it is characterized in that when swash penetrate power certain, the sampling duty ratio γ of front portion
lbe 0.5, latter part of sampling duty ratio γ
rdepart from more than 0.5, the laser power effectively exported from rear portion sampled grating area is larger; When end face coating cannot be carried out, optimize latter part of sampling duty ratio γ
r, the laser power that laser effectively exports from this side end face, sampled grating area one can be improved.
8. the sampling grating semiconductor laser based on phase shift electric control according to 2 of claim, is characterized in that sampled grating area is longer, stronger to the feedback effect of the ± 1 grade of sub-gratings bragg wavelength; When the sampled grating area length stays constant of described laser side, when swash penetrate power certain, opposite side sampled-grating section length is less then larger from the laser power of this side outgoing; When end face coating cannot be carried out, optimize the length of two sampled grating area, the laser power that laser effectively exports from the side end face, sampled grating area one that length is shorter can be improved.
9. the sampling grating semiconductor laser based on phase shift electric control according to claim 6, it is characterized in that the crosstalk for reducing between sampled grating area, phase-shifted region Injection Current, improve the effect changing and introduce phase shift meticulous adjustment laser excitation wavelength, also between sampled grating area and phase-shifted region, carry out electric isolution with He isotopic geochemistry; In introducing phase shift size within the scope of 0.25 π ~ 1.75 π, laser threshold current and normal work, operating current at 2 ~ 3 times of threshold currents time the laser laser power variation that exports very little.
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| CN113991423A (en) * | 2021-09-27 | 2022-01-28 | 南京华飞光电科技有限公司 | Semiconductor laser based on distributed phase compensation technology |
| CN116683291B (en) * | 2023-08-02 | 2023-10-03 | 中国科学院半导体研究所 | Phase shift multi-wavelength semiconductor laser and preparation method thereof |
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