CN114899697A

CN114899697A - Dual-wavelength cascaded semiconductor laser and preparation method thereof

Info

Publication number: CN114899697A
Application number: CN202210818810.2A
Authority: CN
Inventors: 李洵; 奚燕萍; 李文
Original assignee: Rizhao Ai Rui Optoelectronics Technology Co ltd
Current assignee: Rizhao Ai Rui Optoelectronics Technology Co ltd
Priority date: 2022-07-13
Filing date: 2022-07-13
Publication date: 2022-08-12
Anticipated expiration: 2042-07-13
Also published as: CN114899697B

Abstract

The invention discloses a dual-wavelength cascade semiconductor laser and a preparation method thereof, belonging to the field of semiconductor lasers. The invention achieves the purpose of effectively changing the gain peak wavelength by preparing the local platform strip or the channel and forming different active area layer thicknesses locally, thereby realizing the monolithic integration of the dual-wavelength laser. The cascade connection between different active regions can be realized through one-time epitaxy, and the method is simpler and has higher reliability and yield compared with a method needing multiple times of epitaxy. And the prefabricated structure for controlling the growth speed of each region does not need to adopt an additional medium masking layer, thereby avoiding the pollution elements introduced by the medium masking layer.

Description

Dual-wavelength cascaded semiconductor laser and preparation method thereof

Technical Field

The invention relates to the field of semiconductor lasers, in particular to a dual-wavelength cascade semiconductor laser and a preparation method thereof.

Background

With the rapid increase of emerging application requirements of cloud computing cloud storage, ultra-high-definition video and the like, an optical communication system gradually evolves towards a technical direction supporting larger transmission capacity and higher transmission rate, and the requirements provide higher requirements for the performances of chip integration design, high integration, miniaturization, low power consumption and the like of devices and module packaging. The chip integration technology of multi-wavelength mainly includes two types, the first type of hybrid integration, including that a chip is packaged into a discrete laser diode module TO-CAN and then wave combination is carried out through subsequent packaging, or chips of all channels in a gold box are firstly pasted TO a heat sink substrate in a transverse array mode, the chip interval is in millimeter magnitude at the moment, so that all channel lenses required by the subsequent hybrid integration have enough operating space TO carry out light path collimation, and then all channel optical signals are wave-combined and coupled TO an optical fiber through all elements of a spatial light path. The main problems of the mode are that the optical path elements are multiple, the optical path is complex, the size is large, and the packaging process is complex. The second type of monolithic integration is mainly realized by a mode that all wavelength channels are transversely arranged in an array, the interval of all the channels is dozens of microns, electric and optical crosstalk hardly exists among the channels, and the problem of the thermal crosstalk is mainly considered. The combination of the wavelengths of the channels requires the use of a combiner based on planar waveguide technology, such as arrayed waveguide grating AWG or multimode interferometer MMI. The chip manufacturing difficulty of the scheme is high, an active and passive integration process is needed, and the problems of low chip yield, high combiner loss and the like exist.

The wavelength difference of each channel needing to be integrated is different for different application systems. For the case that the wavelength difference is larger than the gain effective coverage of the active region of the material, different active region designs are generally required. On the other hand, different active regions, such as the gain region and the electro-absorption modulation region, need different active region designs. Generally, the ways of monolithic integration of different active regions mainly include termination coupling technology (BJG), Selective Area Growth (SAG) technology, Quantum Well Intermixing (QWI), and the like. The characteristics and the problems of the various techniques are illustrated by the monolithic integration of two different active regions AR1 and AR 2:

1) terminating coupling technique (BJG): the AR1 needs to be epitaxially grown first, then a standard photolithography and etching process is performed on the area where the AR2 needs to be grown, the portion of the AR1 is removed, and finally the AR2 is epitaxially grown again after the area of the AR1 is masked, as shown in fig. 1. The process needs to ensure that the waveguides of AR1 and AR2 are accurately butted, and the butting surface is smooth. The technology enables the design of the two active regions to be completely independent and respectively optimized to the best performance, but various challenges exist in the manufacturing process, the epitaxial growth needs to be carried out at least three times, each process link needs to be strictly controlled, and the manufacturing tolerance is small. The main problems are poor quality of the interface between the two active regions, optical loss and reflection problems caused by rough interface, and reliability problems caused by interface defects.

2) Selective area growth SAG technique: as shown in fig. 2 (a), the technique employs a patterned dielectric layer for masking, during the MOCVD growth process, the precursor organic compound gas is not consumed above the masking layer and diffuses to the unmasked region in the middle of the masking layer, so that the concentration of the gap is increased, and the growth rate is accelerated. A wider masking layer WL will therefore result in a thicker quantum well structure at the gap, resulting in a red-shifted bandgap wavelength compared to the active region within the narrow masking layer WR gap, i.e. the gain peak wavelength of AR1 is greater than that of AR2, as in fig. 2 (b). This technique can accomplish monolithic integration of multiple wavelength regions by one epitaxy. From the performance aspect, since the two regions are different only in the thickness of each layer due to the same epitaxy, it is difficult to optimize the performance of the two regions with different properties, such as one gain region and the other absorption region, simultaneously. Meanwhile, the method is influenced by the diffusion mode of the precursor near the masking dielectric layer, and the components and the surface appearance of the grown material are influenced by the dielectric layer and need to be accurately controlled. Moreover, the dielectric layer used for masking, such as silicon oxide or silicon nitride, introduces oxygen or nitrogen as a contaminant element, which is not favorable for laser operation.

3) Quantum Well Intermixing (QWI): the mutual expansion between the quantum well and the barrier of the active region causes the band gap to be increased, and the wavelength is blue-shifted compared with the non-mutual expansion region. This interdiffusion can be generally initiated in a number of ways, such as impurity-free vacancy induction, ion implantation induction, impurity diffusion induction, laser induction, and the like. The impurity-free vacancy induction process is relatively simple, low in cost and has certain advantages. As shown in FIG. 3, a dielectric film is deposited on the top of the region to be intermixed, and then high-temperature annealing is performed to induce Ga element in the top layer to diffuse into the dielectric film to form vacancies, namely the Ga element diffuses into the active region of the quantum well to cause intermixing. The quantum well intermixing method is difficult to accurately control the band gap change amount.

Disclosure of Invention

The invention aims to provide a dual-wavelength cascade semiconductor laser and a preparation method thereof, which adopt a non-planar platform strip substrate growth technology or a non-planar channel substrate growth technology to realize the monolithic integration of the dual-wavelength laser.

In order to solve the above problems, the present invention provides a dual wavelength cascaded semiconductor laser, which includes a first wavelength laser and a second wavelength laser which are cascaded and have different wavelengths; the active layer of the cascade connection of the first wavelength laser and the second wavelength laser is formed by one-time epitaxial growth on the patterned semiconductor structure; the patterned semiconductor structure is characterized in that the semiconductor structure corresponding to the first wavelength laser comprises a platform strip structure or a channel structure, and the semiconductor structure corresponding to the second wavelength laser does not have a patterned structure or does not have a channel structure or a platform strip structure; the platform strip structure comprises double channels etched on the semiconductor structure and platform strips between the double channels and protruding relative to the double channels; the channel structure includes a single channel etched on a semiconductor construction.

Preferably, the lasing wavelength of the laser is changed by changing any one or more of the width of the double channel, the width and the height of the mesa; or the width and/or the depth of the single channel are/is changed, so that the lasing wavelength of the laser is changed.

Preferably, the two-wavelength cascaded semiconductor laser further comprises a grating layer above or below the active layer.

Preferably, an absorption region is further included between the first wavelength laser and the second wavelength laser, the absorption region is in a laser segment with shorter wavelength, and the absorption region is an electrodeless absorption region or a reverse bias absorption region.

Preferably, the two-wavelength cascaded semiconductor laser comprises a ridge waveguide or a buried heterojunction structure.

The invention also provides a preparation method of the dual-wavelength cascade semiconductor laser, which comprises the following steps:

s1, epitaxially growing a buffer layer on the N-type substrate;

s2, respectively manufacturing Bragg gratings corresponding to the required working wavelength in a first area where the first wavelength laser is located and a second area where the cascaded second wavelength lasers with different lasing wavelengths are located, and burying the gratings;

s3, etching double channels in the first area to form a platform strip, or etching the first area to form a single channel; etching is not carried out on the second area, or double channels are etched in the second area to form a platform strip, or a single channel is etched in the second area;

s4, epitaxially growing an active region;

s5, epitaxially growing a P-type top layer and an ohmic contact layer;

and S6, etching the first electric isolation channel, electrically contacting and windowing, manufacturing a P-side pattern electrode, thinning the back and manufacturing an N-side electrode.

s1, epitaxially growing a buffer layer on the N-type substrate;

s2, etching double channels in a first area where the first wavelength laser is located to form a platform strip, or etching the first area to form a single channel; etching is not carried out on a second area where a second wavelength laser with different cascade lasing wavelengths is located, or a double-channel is etched in the second area to form a platform strip, or a single channel is etched in the second area;

s3, epitaxially growing an active region, a buffer layer and a grating layer, and respectively manufacturing Bragg gratings corresponding to the required working wavelength in the first region and the second region;

s4, epitaxially growing a P-type top layer and an ohmic contact layer;

and S5, etching the first electric isolation channel, electrically contacting and windowing, manufacturing a P-side pattern electrode, thinning the back and manufacturing an N-side electrode.

Preferably, the P-side electrode length of the shorter emission wavelength side laser is reduced, thereby forming an electrodeless absorption region between the first wavelength laser and the second wavelength laser; or, the step of etching the first electrical isolation channel further comprises etching a second electrical isolation channel, which is used for electrically isolating the shorter light-emitting wavelength side laser from the P-side electrode of the absorption region, and manufacturing mutually independent P-side electrodes on the two sections of lasers and the absorption region.

Preferably, the method further comprises fabricating a ridge waveguide before etching the first electrically isolated via.

The method has the advantages that the local bench strips or the channels are prepared, and the speed of epitaxial growth on the local bench strips or the channels is controlled to be increased or reduced in the local area, so that different thicknesses of active area layers are formed locally, and the purpose of effectively changing the wavelength of a gain peak value is achieved. The cascade connection between different active regions or between the active region and the passive region is realized through one-time epitaxy, and the method is simpler and has higher reliability and yield compared with a method needing multiple times of epitaxy. The prefabricated structure for controlling the growth speed of each area does not need to adopt an additional medium masking layer, but is carried out by etching the related platform strip or channel on the substrate, thereby avoiding the pollution element introduced by the medium masking layer. The prepared dual-wavelength cascade integrated device can output signals on the same optical path, and can realize wave combination in a compact structure on the premise of realizing independent work of each working wavelength.

Drawings

FIG. 1: schematic of a cross-section of a terminated coupling technique;

in fig. 2: (a) growing a top view of the masking pattern of the medium for the selected area, (b) growing a schematic cross-sectional view for the selected area;

FIG. 3: quantum well intermixing cross-sectional schematic;

FIG. 4: the cross section of the dual-wavelength cascade semiconductor laser is schematically shown;

in fig. 5: (a) the structure of the substrate based on the platform strip growth technology is shown schematically, (b) the structure of the substrate based on the channel growth technology is shown schematically;

in fig. 6: (a) and (b) quantum well thickness and energy band characteristics for two cascaded monolithically integrated active regions;

FIG. 7: a preparation flow chart of a dual-wavelength cascade semiconductor laser.

In the figure, 401-a first wavelength laser, 402-a second wavelength laser, 403-a light-emitting end face, 404-a backlight end face, 405-a first P-side electrode, 407-a second P-side electrode, 406-a first N-side electrode, 408-a second N-side electrode, 501-a first region, 502-a second region, 503-a stripe, 504-a double channel, 505-a single channel, 601 a first well layer, 602-a second well layer.

Detailed Description

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

The invention provides a dual-wavelength cascade semiconductor laser, as shown in fig. 4, a first wavelength laser 401 (direct modulation laser) with a lasing wavelength of λ 1 and a second wavelength laser 402 (direct modulation laser) with a lasing wavelength of λ 2 are monolithically integrated on the same substrate, an optical exit end face 403 is coated with an antireflection film, a backlight end face 404 is coated with a film that needs to be selected according to the application, such as a high-reflection film, an antireflection film, or a cleavage state, etc., a pump of the first wavelength laser 401 is provided by a first P-side electrode 405 and a first N-side electrode 406, and a pump of the second wavelength laser 402 is provided by a second P-side electrode 407 and a second N-side electrode 408. The first wavelength laser 401 and the second wavelength laser 402 have different target gain peak wavelengths, and can be implemented by using the existing integration technology, such as termination coupling technology (BJG) and selective area growth technology (SAG), in the manufacturing method thereof. Compared with the prior art, the method for realizing the growth based on the platform strip or the channel only needs one-time epitaxial growth without end face butt joint required by BJG, so the manufacture is simple, and the pollution element of the medium masking layer required by the SAG method is not introduced.

The growth material system used In the present invention is not particularly limited, and an InP-AlGaInAs-InGaAsP material system, a GaAs-InGaAs-AlGaAs material system, a GaAs- (In) GaAsP- (Al) GaInP material system, a sapphire-InGaN-AlGaN material system, or the like can be used.

In one embodiment, the dual wavelength cascaded semiconductor laser is fabricated based on a mesa stripe growth technique. Referring to fig. 5 (a), the

first regions

501 and 502 are used to form two laser segments with different lasing wavelengths, the two laser segments share the same substrate, and different patterns are respectively formed on the semiconductor structures on the substrate at the bottom of the two laser segments by using a common photolithography and etching technique. The dual channel 504 is etched in the first region 501 to form a mesa stripe 503, and the second region 502 is not etched.

The etched platform strips 503 cause the substrate structure to be locally uneven, so that the growth elements are unevenly distributed in the area near the platform strips, the growth speed of the epitaxial material in the area above the platform strips is lower than that in the area above a large-area non-etched plane area, and the thickness t of the first well layer 601 of the quantum well active area above the platform strips is formed ₁ A second well layer 602 of thickness t less than the active area of the quantum well over the other large area uniform portions of the substrate ₂ As shown in fig. 6 (a) and (b), respectively.

Width W of the platform 503 _m Height H of mesa stripe 503, and width W of double-sided channel 504 _d The method is used for controlling the thickness of each layer of the two active multi-quantum well regions, so that the energy band structure is changed, and different gain peak wavelengths are formed. As shown in fig. 6, the energy of the sub-bands of both electrons and holes increases with the decrease of the well thickness, the difference of the transition energy levels between the sub-bands increases, and the corresponding transition wavelength decreases. Thereby forming a reduced peak wavelength of gain of the active region over the mesa compared to the peak wavelength of gain of the active region over the planar region.

The two sections of lasers both comprise grating layers, and the grating layers can be positioned below an active region, namely an N-side grating, and also can be positioned above the active region, namely a P-side grating. Optionally, the optical field and carriers of the laser are confined by using a ridge waveguide mode or a buried heterojunction mode.

Referring to fig. 5 (b), a first region 501 and a second region 502 are used for forming two sections of lasers with different lasing wavelengths, the two sections of lasers share the same substrate, and different patterns are respectively formed on semiconductor structures on the substrate at the bottom of the two sections of lasers by using a common photoetching and etching technology. A single channel 505 is etched in the first region 501 and the second region 502 is not etched.

The etched channel 505 causes the substrate structure to be locally uneven, so that growth elements are unevenly distributed in the area near the channel, the growth speed of epitaxial materials in the channel and the area above the channel is higher than that of the epitaxial materials in the large-area non-etched planar area, and the thickness of the well layer forming the quantum well active region in the channel is larger than that of the well layer forming the quantum well active region above other large-area even parts of the substrate. The trend of the resulting band structure with layer thickness can likewise be represented by fig. 6.

Width W of channel _d2 The depth H2 of the channel is used for controlling the thickness of each layer of the two multi-quantum well active regions, so that the energy band structure is changed, and different gain peak wavelengths are formed. As shown in fig. 6, the energy of the sub-bands of both electrons and holes decreases with the increase of the well thickness, the difference in transition energy level between the sub-bands decreases, and the corresponding transition wavelength increases. Thereby forming an increase in the active region gain peak wavelength over the channel region as compared to the active region gain peak wavelength over the planar region.

Optionally, the two-segment laser includes a grating layer, and the grating layer may be located below the active region, i.e., an N-side grating, or above the active region, i.e., a P-side grating. Optionally, the optical field and carriers of the laser are confined by using a ridge waveguide mode or a buried heterojunction mode.

In the above two embodiments, the dual channel 504 is etched in the first region 501 to form the mesa stripe 503, and the second region 502 is not etched; and a single channel 505 is etched in the first region 501, and the second region 502 is not etched. However, in other embodiments, a dual-channel forming mesa may be etched in the first region 501, while a single channel is etched in the second region 502; or double channels are etched in the first region 501 and the second region 502 to form strips, and the parameters of the strips or the double-side channels in the two regions are different, namely the width and the height of the strips in the two regions and the width of the channels on the two sides are different, wherein at least one of the three is different; or a single channel is formed in the first region 501 and the second region 502 by etching, and the parameters of the single channel in the two regions are different, that is, the width or the depth of the channel in the two regions are different.

In the dual-wavelength cascaded semiconductor laser of the above embodiment, a section of electrodeless absorption region may be added between two sections of lasers, and the absorption region retains the stacking structure of the laser on the shorter emission wavelength side. The electrodeless absorbing region serves to absorb and feed back signals on the relatively short wavelength side so that it has a negligible minor effect on longer wavelength lasers.

According to the backlight detection requirement, a reverse bias electrode can be added in the absorption region, namely the applied voltage of the P-side electrode is smaller than that of the N-side electrode. The two sections of lasers and the P-side electrode of the absorption region are mutually independent, and the shorter light-emitting wavelength side laser and the N-side electrode of the absorption region can be shared.

The gratings in the above embodiments may be prepared by any method known in the art, including but not limited to: 1) firstly, epitaxially growing a grating layer, then writing in a grating in an EBL exposure mode, and then etching; 2) writing the grating in a holographic exposure mode, and then etching; 3) nano-imprinting technology; 4) and (3) prefabricating periodic grooves, epitaxially growing a grating four-element layer, directly forming a grating structure and the like.

In the above embodiments, epitaxial growth techniques such as metal organic chemical vapor phase epitaxy (MOCVD), Molecular Beam Epitaxy (MBE), and Liquid Phase Epitaxy (LPE) may be used.

Next, a specific method for manufacturing a two-wavelength cascade semiconductor laser based on a mesa or trench growth technique will be described.

In one embodiment, the dual-wavelength cascaded semiconductor laser uses an N-side grating, and the preparation method comprises:

s1, epitaxially growing a buffer layer on the N-type substrate;

s3, etching double channels in the first area to form a platform strip, not etching the second area, and reserving a large-area plane area;

s4, epitaxially growing an active region;

s5, epitaxially growing a P-type top layer and an ohmic contact layer;

The first electric isolation channel is used for realizing electric isolation of the P-side electrodes of the first wavelength laser and the second wavelength laser. Etching the double channels to form the platform strips or etching to form the single channel by adopting a common photoetching and etching process; the bragg grating may be fabricated using any method known in the art. The epitaxial growth can be performed by Metal Organic Chemical Vapor Deposition (MOCVD), Molecular Beam Epitaxy (MBE), Liquid Phase Epitaxy (LPE), or other epitaxial growth techniques.

A step of forming a ridge waveguide may be further included between steps S5 and S6.

In step S6, forming an electrodeless absorption region between two sections of lasers may be achieved by shortening the P-side electrode length of the shorter emission wavelength side laser. If the absorption section needs to add an electrode to serve as an on-line detector, step S6 further includes a process of etching a second electrically isolated channel, and when preparing the P-side patterned electrode, P-side electrodes independent of each other are formed in the two sections of the laser and the absorption region. The second electrically isolated channel is used to electrically isolate the shorter emission wavelength side laser from the P-side electrode of the absorption region.

In another embodiment, the dual-wavelength cascaded semiconductor laser uses a P-side grating, and the preparation method comprises:

s1, epitaxially growing a buffer layer on the N-type substrate;

s2, etching double channels in a first area where the first wavelength laser is located to form a platform strip, not etching a second area where the second wavelength laser is located, and reserving a large-area plane area;

s3, epitaxially growing an active region, a buffer layer and a grating layer, and respectively manufacturing Bragg gratings corresponding to the required working wavelength in the two regions;

s4, epitaxially growing a P-type top layer and an ohmic contact layer;

The first isolation channel is used for realizing the electrical isolation of the P-side electrodes of the first wavelength laser and the second wavelength laser. Etching double channels to form a platform strip or etching to form a single channel by adopting a common photoetching and etching process; the bragg grating may be fabricated using any method known in the art. The epitaxial growth can be performed by Metal Organic Chemical Vapor Deposition (MOCVD), Molecular Beam Epitaxy (MBE), Liquid Phase Epitaxy (LPE), or other epitaxial growth techniques.

A step of forming a ridge waveguide may be further included between steps S4 and S5.

In step S5, forming an electrodeless absorption region between two sections of lasers may be achieved by shortening the P-side electrode length of the shorter emission wavelength side laser. If the absorption section needs to add an electrode to function as an on-line detector, step S5 further includes a process of etching a second electrically isolated channel, and when preparing the P-side patterned electrode, P-side electrodes are fabricated independently in the two laser sections and the absorption region. The second electrically isolated channel is used to electrically isolate the shorter emission wavelength side laser from the P-side electrode of the absorption region.

The above description is about the preparation method of forming the mesa stripe in the first region where the first wavelength laser is located by etching, and reserving the large-area planar region without etching in the region where the second wavelength laser is located. However, in other embodiments, a single channel may be formed in the first region by etching, and the second region is not etched; or etching double channels in the first region to form a platform strip, and simultaneously etching the second region to form a single channel; or double channels are etched in the first area and the second area to form the platform strips, and the parameters of the platform strips or the channels on two sides of the two areas are different, namely the width and the height of the platform strips of the two areas and the width of the channels on two sides are different, wherein at least one of the three is different; or a single channel is formed in the first area and the second area by etching, and the parameters of the single channel in the two areas are different, namely the width or the depth of the channel in the two areas are different. It is only necessary to prepare corresponding patterns as needed in the step of preparing the patterned semiconductor construct.

In the embodiment, the existing various 10G PON OLTs need to be compatible downward, that is, to support both the conventional low-speed ONU and the ONU with a 10G rate, a 10G 1577nm band laser and a 2.5G or 1.25G 1490nm band laser are usually adopted for downlink, where the 1577nm band laser is a laser with a light-emitting wavelength in the range of 1575-1580nm, and the 1490nm band laser is a laser with a light-emitting wavelength in the range of 1480-1500 nm. In the embodiment, the monolithic integration of the 1490nm band laser and the 1577nm band laser is completed through the same epitaxial growth, and the output is output through the same optical path near the output end face of the 1490nm band, so that the wave combination is completed in a compact and low-cost manner.

In the embodiment, the lasers of the two wave bands are monolithically integrated in the same device, and a ridge waveguide structure, an N-side or P-side grating and an InP-AlGaInAs-InGaAsP material system are adopted.

In this embodiment, a method for manufacturing an N-side dual-wavelength cascaded semiconductor laser is shown in fig. 7, and includes:

s1, epitaxially growing an InP buffer layer and a grating layer on the N-type InP substrate;

s2, writing Bragg grating electron beam Exposure (EBL) in a 1490nm region and a 1577nm region, etching the InGaAsP grating, and burying the grating;

s3, common photoetching and etching double channels are adopted in a 1490nm area to form a platform strip, the 1577nm area is not etched, and a large-area plane area is reserved;

s4, epitaxially growing an AlGaInAs active region, a P-type InP cladding layer, an InGaAsP ohmic contact layer and an InGaAs ohmic contact layer;

s5, forming a ridge waveguide by standard photoetching and etching;

s6, etching the electric isolation channel and opening the contact window of the ridge top;

and S7, manufacturing a P-side pattern electrode, thinning the back and manufacturing an N-side electrode.

According to the application requirement, for example, 1490nm needs to add an absorption section near 1577nm, the P-side electrode length can be reduced in step S7, so that no electrode is located above the absorption section. If the absorption section requires the addition of electrodes for on-line detector function, the 1490nm gain and the electrical isolation between the absorption sections can be added in step S6, and the 1490nm P-side pattern electrode can be changed in step S7, i.e., two separate P-side electrodes are used.

In this embodiment, the method for manufacturing a P-side dual-wavelength cascaded semiconductor laser includes:

s1, epitaxially growing an InP buffer layer on the N-type InP substrate;

s2, forming a platform strip in a 1490nm area by adopting common photoetching and etching double channels, not etching the 1577nm area, and reserving a large-area plane area;

s3, epitaxially growing an AlGaInAs active region, an InP buffer layer and an InGaAsP grating layer;

s4, writing Bragg grating electron beam Exposure (EBL) in a 1490nm region and a 1577nm region, and etching InGaAsP grating;

s5, grating burying is carried out, and epitaxial growth of P-type InP cladding layer, InGaAsP and InGaAs ohmic contact layer is carried out;

s6, forming a ridge waveguide by standard photoetching and etching;

s7, etching the electric isolation channel and opening the contact window of the ridge top;

and S8, manufacturing a P-side pattern electrode, thinning the back and manufacturing an N-side electrode.

According to the application requirement, for example, 1490nm needs to add an absorption section near 1577nm, the P-side electrode length can be reduced in step S8, so that no electrode is located above the absorption section. If the absorption section requires the addition of electrodes for on-line detector function, the 1490nm gain and the electrical isolation between the absorption sections can be added in step S7, and the 1490nm P-side pattern electrode can be changed in step S8, i.e., two separate P-side electrodes are used.

The technical principle of the present invention is described above in connection with specific embodiments. The description is made for the purpose of illustrating the principles of the invention and should not be construed in any way as limiting the scope of the invention. Based on the explanations herein, those skilled in the art will be able to conceive of other embodiments of the present invention without inventive effort, which would fall within the scope of the present invention.

Claims

1. A dual-wavelength cascade semiconductor laser is characterized in that the dual-wavelength cascade semiconductor laser comprises a first wavelength laser and a second wavelength laser which are cascaded and have different wavelengths; the active layer of the cascade connection of the first wavelength laser and the second wavelength laser is formed by one-time epitaxial growth on the patterned semiconductor structure; the patterned semiconductor structure is characterized in that the semiconductor structure corresponding to the first wavelength laser comprises a platform strip structure or a channel structure, and the semiconductor structure corresponding to the second wavelength laser does not have a patterned structure or does not have a channel structure or a platform strip structure; the platform strip structure comprises double channels etched on the semiconductor structure and platform strips between the double channels and protruding relative to the double channels; the channel structure includes a single channel etched on a semiconductor construction.

2. The dual wavelength cascaded semiconductor laser of claim 1, wherein a lasing wavelength of the laser is changed by changing any one or more of a width of the double channel, a width and a height of the mesa; or the width and/or the depth of the single channel are/is changed, so that the lasing wavelength of the laser is changed.

3. The dual wavelength cascaded semiconductor laser of claim 1, further comprising a grating layer, the grating layer being above or below the active layer.

4. The dual wavelength cascaded semiconductor laser of claim 1, further comprising an absorption region between the first wavelength laser and the second wavelength laser, the absorption region being in a shorter wavelength laser band, the absorption region being an electrodeless absorption region or a reverse biased absorption region.

5. The dual wavelength cascaded semiconductor laser of claim 1, wherein the dual wavelength cascaded semiconductor laser comprises a ridge waveguide or a buried heterojunction structure.

6. A method for preparing a dual-wavelength cascade semiconductor laser is characterized by comprising the following steps:

s1, epitaxially growing a buffer layer on the N-type substrate;

s4, epitaxially growing an active region;

s5, epitaxially growing a P-type top layer and an ohmic contact layer;

7. A method for preparing a dual-wavelength cascade semiconductor laser is characterized by comprising the following steps:

s1, epitaxially growing a buffer layer on the N-type substrate;

s4, epitaxially growing a P-type top layer and an ohmic contact layer;

8. The manufacturing method according to any one of claims 6 to 7, wherein the lasing wavelength of the laser is changed by changing any one or more of the width of the double channel, the width and the height of the mesa; or the width and/or the depth of the single channel are/is changed, so that the lasing wavelength of the laser is changed.

9. The production method according to any one of claims 6 to 7, wherein a P-side electrode length of the shorter emission wavelength side laser is shortened to form an electrodeless absorption region between the first wavelength laser and the second wavelength laser; or, the step of etching the first electrical isolation channel further comprises etching a second electrical isolation channel, which is used for electrically isolating the shorter light-emitting wavelength side laser from the P-side electrode of the absorption region, and manufacturing mutually independent P-side electrodes on the two sections of lasers and the absorption region.

10. A method of manufacturing as claimed in any of claims 6 to 7, further comprising fabricating a ridge waveguide prior to etching the first electrically isolated via.