CN111903022A

CN111903022A - Semiconductor laser device and manufacturing method and equipment thereof

Info

Publication number: CN111903022A
Application number: CN201980022251.0A
Authority: CN
Inventors: 任正良; 黄利新; 操日祥
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2019-01-31
Filing date: 2019-01-31
Publication date: 2020-11-06
Also published as: WO2020155029A1

Abstract

A semiconductor laser device, a method and an apparatus for manufacturing the same. The semiconductor laser device includes: the device comprises a first laser and a second laser, wherein the first laser and the second laser are attached to the same substrate layer; the n-electrode of the first laser and the n-electrode of the second laser are independent of each other, and the p-electrode of the first laser and the p-electrode of the second laser are independent of each other; when a first signal is added to an electrode of the first laser, a current generated in the first laser forms a first current channel, when a second signal is added to an electrode of the second laser, a current generated in the second laser forms a second current channel, and the modulation of the first laser by the first signal and the modulation of the second laser by the second signal are independent of each other; the second laser includes a cap layer for achieving mutual isolation between the first current path and the second current path.

Description

Semiconductor laser device and manufacturing method and equipment thereof

Technical Field

The embodiment of the application relates to the field of communication, in particular to a semiconductor laser device and a manufacturing method and equipment thereof.

Background

At present, the demand for information is rapidly increasing, and the data rate and data capacity of optical fiber communication systems are rapidly increasing. Currently, a mainstream Gigabit Passive Optical Network (GPON) is gradually difficult to meet the continuously increasing demand of a high bandwidth service for bandwidth, and an operator needs to consider a new technology to provide higher bandwidth and better service, so as to improve user experience.

The evolution of the current mainstream GPON towards the higher rate 10GPON is a necessary trend. The receiving wavelength of the GPON is 1310 nanometers (nm), the transmitting wavelength of the GPON is 1490nm, the receiving wavelength of the 10GPON is 1270nm, and the transmitting wavelength of the 10GPON is 1577 nm. In the process of upgrading the GPON to the 10G GPON, an operator needs to consider various requirements, including problems of reusing existing resources, rapid deployment, backward and forward compatibility, and the like. In order to be compatible with smooth network upgrade and reduce construction cost, a combo PON combining a GPON and a 10G PON has emerged.

A combo optical device is a core device in a combo PON and is used for realizing conversion of optical and electrical signals. The combined optical device needs to include: the structure of the combined optical device is very complex due TO the emission transistor shells (TO) of 1490nm and 1577nm and the receiving TO of 1310nm and 1270nm and the corresponding isolators and filters, so that the cost of the combined optical device is greatly increased. In order to reduce the cost of the combined optics, new techniques are needed to reduce the cost.

The TO emission in both 1490nm and 1577nm bands is the largest cost component of the combined optics, requiring the fabrication of widely spaced dual wavelength lasers on the same chip. The prior art provides a laser structure for realizing dual-wavelength lasing by using two groups of independent quantum wells, two lasers provided by the prior art are respectively provided with a group of quantum wells with different gain peaks, the two groups of quantum wells with different gain peaks are epitaxially grown on the same substrate, and the two lasers share the same group of electrodes.

Although the dual-wavelength laser provided by the prior art can realize dual-wavelength lasing with a wider distance, the power of two wavelengths is difficult to balance, and one wavelength always dominates in the lasing process. Because the lasers with two wavelengths share the same group of electrodes, the two lasers cannot independently perform signal modulation, so that the two lasers cannot independently perform optimized design, and the performance index of the lasers is reduced.

Disclosure of Invention

The embodiment of the application provides a semiconductor laser device, a manufacturing method and equipment thereof, which are used for independently and optimally designing a single laser and improving the performance index of the laser.

In order to solve the above technical problem, an embodiment of the present application provides the following technical solutions:

in a first aspect, an embodiment of the present application provides a semiconductor laser device, including: the device comprises a first laser and a second laser, wherein the first laser and the second laser are attached to the same substrate layer; the n-electrode of the first laser and the n-electrode of the second laser are independent of each other, and the p-electrode of the first laser and the p-electrode of the second laser are independent of each other; when a first signal is added to an electrode of the first laser, a current generated in the first laser forms a first current channel, when a second signal is added to an electrode of the second laser, a current generated in the second laser forms a second current channel, and the modulation of the first laser by the first signal and the modulation of the second laser by the second signal are independent of each other; the second laser includes a cap layer for achieving mutual isolation between the first current path and the second current path.

In an embodiment of the present application, a semiconductor laser device includes: the device comprises a first laser and a second laser, wherein the first laser and the second laser are attached to the same substrate layer; the n-electrode of the first laser and the n-electrode of the second laser are independent of each other, and the p-electrode of the first laser and the p-electrode of the second laser are independent of each other; when a first signal is added to an electrode of a first laser, a current generated in the first laser forms a first current channel, when a second signal is added to an electrode of a second laser, a current generated in the second laser forms a second current channel, the modulation of the first laser by the first signal and the modulation of the second laser by the second signal are mutually independent, and the second laser comprises a cover layer used for realizing mutual isolation between the first current channel and the second current channel. Because two lasers are arranged in the semiconductor laser device in the embodiment of the application, the two lasers can form mutually isolated different current channels when signals are added, each laser can be independently and optimally designed according to the characteristics of the laser, and no electric crosstalk exists between the two lasers, so that each laser can independently add a modulation signal, and the performance index of the laser is promoted.

In one possible implementation of the first aspect, the first laser comprises: a first n-electrode and a first p-electrode; the second laser includes: a second n-electrode and a second p-electrode; the first signal is injected from the first p-electrode to the first laser and output from the first n-electrode; the second signal is injected from the second p-electrode to the second laser and output from the second n-electrode. In practical applications, the isolation of the current path between different lasers in the semiconductor laser device may be implemented based on a hierarchical structure inside the second laser, for example, a cover layer is disposed in the second laser for implementing the isolation between the first current path and the second current path, and the modulation of each signal on the corresponding laser is independent.

In one possible implementation of the first aspect, the first laser further comprises: the first n electrode and the first p electrode are positioned at two ends of the first epitaxial region; the second laser further comprises: a second epitaxial region, the second n-electrode and the second p-electrode being located at both ends of the second epitaxial region; the second n-electrode, the second p-electrode and the second epitaxial region are located on the same side of the cap layer; the first epitaxial region and the second epitaxial region are isolated from each other through the cover layer, and the first epitaxial region and the second epitaxial region are located on two sides of the cover layer. The epitaxial region in the laser in the embodiment of the present application refers to a hierarchical structure generated by epitaxial growth on a substrate layer, and a material layer corresponding to an epitaxial material can be generated when different epitaxial materials are used for epitaxial growth in the laser. The epitaxial region in the embodiment of the present application refers to a general term of the internal material layer of the laser, and a specific hierarchical structure may be generated when a specific epitaxial material is used for epitaxial growth.

In one possible implementation of the first aspect, the first epitaxial region includes: a first quantum well; the second epitaxial region includes: a second quantum well, the first quantum well and the second quantum well being formed by the same epitaxial growth; the first quantum well, the first p-electrode, the second n-electrode, the second quantum well, the second p-electrode, and the cap layer are all located above the substrate layer; the first n electrode is positioned below the substrate layer; the first p-electrode is positioned above the first quantum well; the cap layer is located between the first quantum well and the second quantum well; the second n-electrode is positioned below the second quantum well, and the second p-electrode is positioned above the second quantum well; the first p-electrode and the second n-electrode are separated by the capping layer; the first p-electrode and the second p-electrode are separated by the cover layer and the second quantum well. In the embodiment of the application, when a signal is applied to the electrode of each laser, each laser can form a current channel belonging to the respective laser, each laser can be independently and optimally designed according to the characteristics of the laser, no electric crosstalk exists between the two lasers, and therefore each laser can independently add a modulation signal, therefore, the performance index of the laser is improved.

In one possible implementation of the first aspect, the first epitaxial region further includes: a first lower separation limiting layer, a first upper separation limiting layer; the second epitaxial region further comprises: a second lower separation limiting layer, a second upper separation limiting layer; wherein the first lower separation limiting layer is located between the substrate layer and the first quantum well; the first upper separation confinement layer is located above the first quantum well and below the cap layer; the second lower separation confinement layer is located between the cap layer and the second quantum well; the second upper separation confinement layer is located above the second quantum well. In the embodiment of the present application, the upper separation limiting layer and the lower separation limiting layer are respectively defined according to the difference in the position distribution of the separation limiting layers in the laser. The separation limiting layer is used for enlarging the optical field distribution of the laser so as to reduce the optical field intensity of the quantum well region, further reduce the thermal effect of the device, enhance the limiting effect on electrons, and enable more carriers (electrons and holes) to be compounded in the quantum well (namely the active region) to generate photons.

In one possible implementation of the first aspect, the first epitaxial region further includes: a first grating layer; the second epitaxial region further comprises: a second grating layer; the first grating layer is provided with a first grating, and the second grating layer is provided with a second grating; the first grating layer is positioned above the first upper separation limiting layer; the second grating layer is positioned above the second upper separation limiting layer; the cover layer is located above the first grating layer. In the embodiment of the application, the first laser includes a grating layer therein, and the second laser also includes a grating layer therein. The grating layer is used for manufacturing gratings in the laser.

In one possible implementation of the first aspect, the first epitaxial region further includes: a first contact layer, the first contact layer comprising: a first ridge waveguide; the second epitaxial region further comprises: a second contact layer, the second contact layer comprising: a second ridge waveguide; the first contact layer is located between the first grating layer and the first p-electrode; the second contact layer is located between the second grating layer and the second p-electrode. The contact layer may be made of P-type indium phosphide (P-InP). A ridge waveguide may be etched in the contact layer.

In one possible implementation of the first aspect, the first epitaxial region further includes: a first silicon dioxide layer; the second epitaxial region further comprises: a second silicon dioxide layer; the first silicon dioxide layer is positioned on the end face of the first ridge waveguide and positioned between the first grating layer and the first p electrode; the second silicon dioxide layer is located on an end face of the second ridge waveguide, and the second silicon dioxide layer is located between the second grating layer and the second p-electrode. Silicon dioxide is an insulating layer (also called a passivation layer) of the laser, and is mainly used to limit the current injection area.

In one possible implementation of the first aspect, the first ridge waveguide and the second ridge waveguide have the same thickness; the lowest plane where the first ridge waveguide is located is lower than the lowest plane where the second ridge waveguide is located. In the embodiment of the application, the first contact layer in the first laser and the second contact layer in the second laser are formed by simultaneous growth, and ridge waveguide etching is respectively carried out on the first contact layer and the second contact layer, so that a first ridge waveguide of the first laser and a second ridge waveguide of the second laser are formed. In order to ensure the epitaxial quality of the two quantum wells, the growth of the two quantum wells is completed in one time of epitaxy, but the first laser only uses the first quantum well without using the second quantum well when working, and the second laser only uses the second quantum well without using the first quantum well when working. In the embodiment of the present application, a portion of the hierarchical structure related to the second quantum well is etched away in order to fabricate the first laser, which may result in the second ridge waveguide being higher than the first ridge waveguide, and finally forming a staggered-height device shape.

In one possible implementation of the first aspect, the first laser and the second laser are arranged side-by-side on the substrate layer. In an embodiment of the application, a plurality of lasers are arranged side by side on the substrate layer. The side-by-side arrangement is a distribution mode of a plurality of lasers on a substrate layer, and two lasers can be formed on the substrate layer side by side through two times of epitaxial growth.

In one possible implementation of the first aspect, the second laser is superimposed on the first laser, and the first laser is disposed on the substrate layer. In the embodiment of the application, the semiconductor laser device can complete the growth of two quantum wells in one epitaxial growth, part of the quantum wells are etched by selective etching, and the wide-wavelength-interval dual-wavelength laser is manufactured by using different quantum wells, so that the epitaxial frequency is reduced, the performance index and the yield of the laser are favorably improved, and the manufacturing cost of the laser is reduced.

In a second aspect, an embodiment of the present application further provides a multi-wavelength laser, including: a semiconductor laser device.

In a second aspect of the present application, the multi-wavelength laser includes a semiconductor laser device having a structure as described in the foregoing first aspect and in various possible implementations, and the foregoing explanation of the first aspect and the various possible implementations is for details.

In a third aspect, an embodiment of the present application further provides a semiconductor chip, including: a semiconductor laser device.

In a third aspect of the present application, the semiconductor chip includes a constituent module of the semiconductor laser device having the structure as described in the foregoing first aspect and in various possible implementations, and the details are described in the foregoing description of the first aspect and the various possible implementations.

In a fourth aspect, an embodiment of the present application further provides an optical module, including: a semiconductor laser device.

In a fourth aspect of the present application, the optical module includes a component module of the semiconductor laser device having the structure described in the foregoing first aspect and various possible implementations, and the details are described in the foregoing description of the first aspect and various possible implementations.

In a fifth aspect, an embodiment of the present application further provides an Optical Line Terminal (OLT), including: an optical module.

In a fifth aspect of the present application, the constituent modules of the optical module included in the optical line terminal have the structures as described in the foregoing fourth aspect and in various possible implementations, which are described in detail in the foregoing description of the fourth aspect and in various possible implementations.

In a sixth aspect, an embodiment of the present application further provides an Optical Network Unit (ONU), including: an optical module.

In a sixth aspect of the present application, the constituent modules of the optical module included in the optical network unit have the structures as described in the foregoing fourth aspect and various possible implementations, which are described in detail in the foregoing description of the fourth aspect and various possible implementations.

In a seventh aspect, an embodiment of the present application further provides a method for manufacturing a semiconductor laser device, including: respectively manufacturing a first laser and a second laser on the same substrate layer, wherein the second laser comprises a cover layer, and a first current channel of the first laser and a second current channel of the second laser are isolated from each other through the cover layer; the first laser and the second laser are provided with n-electrodes that are independent of each other, and the first laser and the second laser are provided with p-electrodes that are independent of each other.

The semiconductor laser device can be generated through the manufacturing method provided by the embodiment of the application, the two lasers are arranged in the semiconductor laser device, the two lasers can form mutually isolated different current channels when signals are added, each laser can be independently and optimally designed according to the characteristics of the laser, and no electric crosstalk exists between the two lasers, so that each laser can independently add a modulation signal, and the performance index of the laser is favorably improved.

In a possible implementation of the seventh aspect, the fabricating the first laser and the second laser on the same substrate layer respectively includes: carry out epitaxy for the first time on the front of substrate layer, through epitaxial growth goes out first epitaxial structure for the first time, first epitaxial structure is from up including following hierarchical structure down: the laser comprises a first epitaxial region, a cover layer and a second epitaxial region, wherein the first epitaxial region belongs to the first laser, and the second epitaxial region belongs to the second laser; carrying out selective etching on the left side surface and the right side surface of the first epitaxial structure to obtain a second epitaxial structure; and carrying out selective etching on the right side surface of the second epitaxial structure to obtain a third epitaxial structure, wherein the cover layer on the right side surface of the third epitaxial structure is etched, and the cover layer is reserved on the left side surface of the third epitaxial structure. In this application embodiment, can use multiple epitaxial material at first time external delay, grow out first epitaxial structure through first epitaxy, this first epitaxial structure includes following hierarchical structure from bottom to top: the first epitaxial region, the cover layer and the second epitaxial region. The first epitaxial region belongs to the first laser, the second epitaxial region belongs to the second laser, the cover layer plays a role in isolating the first laser from the second laser, and the cover layer also plays a role in providing a substrate for the second laser. After the first epitaxial structure is obtained, selective etching is performed on the left and right side surfaces of the first epitaxial structure, for example, the left and right ends of the second epitaxial region in the first epitaxial structure may be etched away, and at this time, the second epitaxial structure may be obtained. And then, carrying out second selective etching to etch the cover layer on the right side surface of the second epitaxial structure, thereby obtaining a third epitaxial structure. The third epitaxial structure has two end faces: a right side and a left side, the cap layer on the right side of the third epitaxial structure being etched away, the cap layer remaining on the left side of the third epitaxial structure.

In one possible implementation of the seventh aspect, the configuring the first laser and the second laser with n-electrodes independent of each other and the configuring the first laser and the second laser with p-electrodes independent of each other includes: manufacturing a first p electrode above the first epitaxial region; manufacturing a second p electrode above the second epitaxial region; manufacturing a second n electrode on the cover layer on the left side surface of the third epitaxial structure, wherein the second n electrode and the second p electrode belong to the second laser; and thinning the back surface of the substrate layer, and manufacturing a first n electrode on the back surface of the substrate layer, wherein the first n electrode and the first p electrode belong to the first laser. In the embodiment of the application, when a signal is applied to the electrode of each laser, each laser can form a current channel belonging to the respective laser, each laser can be independently and optimally designed according to the characteristics of the laser, and no electric crosstalk exists between the two lasers, so that each laser can independently add a modulation signal, therefore, the performance index of the laser is improved.

In a possible implementation of the seventh aspect, the performing a first epitaxy on the front surface of the substrate layer, and growing a first epitaxial structure through the first epitaxy, further includes: carrying out first epitaxial growth on the front surface of the substrate layer to respectively grow a first lower separation limiting layer, a first quantum well, a first upper separation limiting layer, a first grating layer, the cover layer, a second lower separation limiting layer, a second quantum well, a second upper separation limiting layer and a second grating layer; wherein the first lower confinement layer, the first quantum well, the first upper confinement layer and the first grating layer all belong to the first epitaxial region; the second lower confinement layer, the second quantum well, the second upper confinement layer, and the second grating layer all belong to the second epitaxial region. In the embodiment of the application, the upper layer and the lower layer of the first quantum well respectively use the separation limiting layer, the upper layer and the lower layer of the second quantum well respectively use the separation limiting layer, and the separation limiting layers are respectively defined as the upper separation limiting layer and the lower separation limiting layer according to different position distributions of the separation limiting layers in the laser.

In a possible implementation of the seventh aspect, the method further includes: after growing the first grating layer on the first upper separation limiting layer, manufacturing a first grating on the first grating layer, wherein the first grating belongs to the first laser; and after growing the second grating layer on the second upper separation limiting layer, manufacturing a second grating on the second grating layer, wherein the second grating belongs to the second laser.

In a possible implementation of the seventh aspect, after the performing selective etching on the right side surface of the second epitaxial structure to obtain a third epitaxial structure, the method further includes: growing a protective layer on the cap layer on the left side of the third epitaxial structure. The protective layer may be silicon dioxide, and the main function of the protective layer is to ensure that the portion for manufacturing the second n electrode is not grown with a P-InP layer in the secondary epitaxy process.

In one possible implementation of the seventh aspect, after the growing the protective layer on the cap layer on the left side of the third epitaxial structure, the method further includes: respectively carrying out secondary epitaxy on the first grating layer and the second grating layer, growing a first contact layer on the first grating layer through the secondary epitaxy, and growing a second contact layer on the second grating layer; etching a first ridge waveguide from the first contact layer and etching a second ridge waveguide from the second contact layer, wherein the first ridge waveguide belongs to the first epitaxial region and the second ridge waveguide belongs to the second epitaxial region; wherein the first contact layer is located between the first grating layer and the first p-electrode; the second contact layer is located between the second grating layer and the second p-electrode. In the embodiment of the application, only two times of epitaxial growth are needed, and the first contact layer and the second contact layer can be grown through the second time of epitaxy, the contact layer can be made of a P-InP material, and the ridge waveguide can be etched on the contact layer.

In one possible implementation of the seventh aspect, after the etching a first ridge waveguide from the first contact layer and a second ridge waveguide from the second contact layer, the method further includes: growing a first silicon dioxide layer on the first grating layer and the first ridge waveguide, and growing a second silicon dioxide layer on the second grating layer and the second ridge waveguide; wherein the first silicon dioxide layer belongs to the first epitaxial region and the second silicon dioxide layer belongs to the second epitaxial region. In the embodiment of the application, the first laser comprises a silicon dioxide layer, and the second laser also comprises a silicon dioxide layer. Silicon dioxide is an insulating layer (also called a passivation layer) of the laser, and is mainly used to limit the current injection area.

In one possible implementation of the seventh aspect, after growing a first silicon dioxide layer on the first grating layer and the first ridge waveguide and growing a second silicon dioxide layer on the second grating layer and the second ridge waveguide, the method further includes: cleaning the protective layer from the cap layer on the left side of the third epitaxial structure; etching away the first silicon dioxide layer on top of the first ridge waveguide and etching away the second silicon dioxide layer on top of the second ridge waveguide. In the embodiment of the application, only the top of the first ridge waveguide, the top of the second ridge waveguide and the lower part of the second n electrode are not covered by silica, so that silica distribution ensures that current injected into the second ridge waveguide can only flow out of the second n electrode, and current injected into the first ridge waveguide can only flow out of the first n electrode, so that the first laser and the second laser can have mutually isolated current channels, and the two lasers can independently add modulation signals.

In one possible implementation of the seventh aspect, the first p-electrode is located above the first silicon dioxide layer and above a top of the first ridge waveguide; the second p-electrode is located over the second silicon dioxide layer and over a top of the second ridge waveguide. After windowing the silicon dioxide layer, the silicon dioxide on the tops of the two ridge waveguides can be etched away, and a P electrode is added above the silicon dioxide layer, so that a current channel can be established between the P electrode and a hierarchical structure in the laser.

Drawings

Fig. 1 is a schematic structural diagram of a semiconductor laser device according to an embodiment of the present disclosure;

fig. 2 is a schematic view of another structure of a semiconductor laser device according to an embodiment of the present disclosure;

fig. 3 is a schematic view of another structure of a semiconductor laser device according to an embodiment of the present disclosure;

fig. 4 is a schematic block flow diagram illustrating a method for fabricating a semiconductor laser device according to an embodiment of the present disclosure;

fig. 5a is a schematic structural diagram in a manufacturing process of a dual-wavelength laser according to an embodiment of the present application;

fig. 5b is a schematic structural diagram of another manufacturing process of a dual-wavelength laser according to an embodiment of the present disclosure;

fig. 5c is a schematic structural diagram of another manufacturing process of a dual-wavelength laser according to an embodiment of the present disclosure;

fig. 5d is a schematic structural diagram of another manufacturing process of a dual-wavelength laser according to an embodiment of the present disclosure;

fig. 5e is a schematic structural diagram of another manufacturing process of a dual-wavelength laser according to an embodiment of the present disclosure;

fig. 5f is a schematic structural diagram of another manufacturing process of a dual-wavelength laser according to an embodiment of the present disclosure;

fig. 5g is a schematic structural diagram of another manufacturing process of a dual-wavelength laser according to an embodiment of the present disclosure.

Detailed Description

Embodiments of the present application are described below with reference to the accompanying drawings.

The terms "first," "second," and the like in the description and in the claims of the present application and in the above-described drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and are merely descriptive of the various embodiments of the application and how objects of the same nature can be distinguished. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Embodiments of the present disclosure provide a semiconductor laser device, which can be used to generate signals with at least two different wavelengths, depending on the number of lasers included in the semiconductor laser device.

The embodiment of the present application also provides a multi-wavelength laser, which may include the aforementioned semiconductor laser device. The multi-wavelength laser can be used for manufacturing multi-wavelength signals with wide intervals on the same chip. For example, the multi-wavelength laser may include: the dual wavelength laser may be, for example, 1490nm and 1577 nm.

The embodiment of the present application further provides a semiconductor chip, which may include the aforementioned semiconductor laser device.

An embodiment of the present application further provides an optical module, including: a semiconductor laser device.

An embodiment of the present application further provides an optical line terminal, including: the optical module described above.

An embodiment of the present application further provides an optical network unit, including: the optical module described above.

The optical line terminal and the optical network unit provided by the embodiment of the application can be components of a Passive Optical Network (PON) system, the optical line terminal is used for connecting a network backbone, and the optical network unit is used for connecting an area network or a home user.

Next, a semiconductor laser device provided in an embodiment of the present application will be exemplified. As shown in fig. 1, a semiconductor laser device 100 according to an embodiment of the present application includes: a first laser 101 and a second laser 102, wherein,

the first laser 101 and the second laser 102 are attached to the same substrate layer 103;

the n-electrode of the first laser 101 and the n-electrode of the second laser 102 are independent of each other, and the p-electrode of the first laser 101 and the p-electrode of the second laser 102 are independent of each other;

when a first signal is added to an electrode of the first laser 101, a current generated in the first laser 101 forms a first current channel, when a second signal is added to an electrode of the second laser 102, a current generated in the second laser 102 forms a second current channel, and the modulation of the first laser 101 by the first signal and the modulation of the second laser 102 by the second signal are independent of each other;

the second laser 102 comprises a cap layer 104, the cap layer 104 being used to achieve mutual isolation between the first current path and the second current path.

In the embodiment of the present application, the number of lasers included in the semiconductor laser device may be two or more, and fig. 1 illustrates an example in which two lasers are included in the semiconductor laser device. When three lasers are included in the semiconductor laser device, the structural features between the two lasers still satisfy the constraints of the above-mentioned composition structure and connection relationship of the two lasers shown in fig. 1, and in the following embodiments, the semiconductor laser device including two lasers is still exemplified, but the description is not limited to the composition structure of the semiconductor laser device provided in the embodiments of the present application.

In the embodiment of the application, the substrate layer can be made of n-type indium phosphide (n-InP) material, and a plurality of lasers in the semiconductor laser device can be commonly attached to the same substrate layer.

In the embodiments of the present application, each laser included in the semiconductor laser device is provided with an electrode belonging to the respective laser individually, i.e., the electrodes are not shared between different lasers. Specifically, the n-electrode of the first laser and the n-electrode of the second laser are independent from each other, that is, each laser has an n-electrode dedicated to the laser, and the n-electrodes are not shared among the plurality of lasers. Similarly, the p-electrode of the first laser 101 and the p-electrode of the second laser are independent of each other, i.e., each laser has a p-electrode dedicated to that laser, and the p-electrodes are not shared among the plurality of lasers. In the embodiments of the present application, a plurality of lasers in a semiconductor laser device are commonly attached to the same substrate layer, but each laser may form a current path belonging to the respective laser. The current channel refers to a current generated in the laser when a signal is applied to an electrode of the laser, and the current moves in the laser to form a current channel.

In an embodiment of the present application, the first signal may be used for modulation of a first laser, the second signal may be used for modulation of a second laser, and the first signal and the second signal are electrical signals that need to be added to electrodes of the laser to achieve modulation of the laser. Wherein the first signal may be added to the electrodes of the first laser and the second signal to the electrodes of the second laser. For example, when the same substrate layer to which the first laser and the second laser are attached is an n-type substrate, the first signal may be injected from the p-electrode of the first laser and the second signal may be injected from the p-electrode of the second laser. For example, when the same substrate layer to which the first laser and the second laser are attached is a p-type substrate, a first signal may be injected from the n-electrode of the first laser and a second signal may be injected from the n-electrode of the second laser. The manner in which the electrical signal is injected into the laser is used herein for example and not as a limitation to the present application.

In the embodiment of the application, the current channels of each laser are isolated from each other through the cover layer, wherein the isolation of the current channels of different lasers from each other means that the charge movement in different current channels is not affected by the charge movement in other lasers. When a signal is applied to the electrode of each laser in the embodiment of the application, each laser can form a current channel belonging to the laser, and each laser can be independently and optimally designed according to the characteristics of the laser. There is not electric crosstalk between first laser and the second laser, or electric crosstalk between first laser and the second laser is very little, can not influence the performance index of respective laser to every laser all can be independent adds modulation signal, consequently helps promoting the performance index of laser.

In some embodiments of the present application, each laser may have an n-electrode and a p-electrode, such as shown in fig. 1, the first laser 101 comprising: a first n-electrode 1011 and a first p-electrode 1012; the second laser 102 includes: a second n electrode 1021 and a second p electrode 1022;

a first signal is injected from the first p-electrode 1012 to the first laser 101 and is output from the first n-electrode 1011;

a second signal is injected from the second p-electrode 1022 to the second laser 102 and is output from the second n-electrode 1021.

The wide arrows in fig. 1 indicate the current paths generated when a signal is applied to the laser, and the current paths are schematic illustrations for explaining that the first current path and the second current path are in an isolated relationship. In practical applications, the isolation of the current path between different lasers in the semiconductor laser device may be implemented based on a hierarchical structure inside the second laser, for example, a cap layer 104 is disposed in the second laser, and the cap layer 104 is used to implement the mutual isolation between the first current path and the second current path.

In the present embodiment, the cap layer 104 may be used to isolate the first current path and the second current path from each other. The cap layer 104 may be an n-type doped material to ensure that the second laser 102 can form a complete PIN structure. The cap layer 104 may also serve as a supporting layer for the second n-electrode 1021 of the second laser 102, and the second current path may be formed independent of the first current path by the cap layer 104, for example, the second current path may include: a current generated by the second signal is injected into the second laser 102 from the second p-electrode 1022, and then flows out of the current path formed in the second n-electrode 1021 after passing through the cap layer 104.

In some embodiments of the present application, cap layer 104 comprises: an n-type indium phosphide (n-InP) layer and an Intrinsic indium phosphide (I-InP) layer, Intrinsic meaning undoped. The n-InP layer may be used to form a PIN junction of the second laser, and an intrinsic InP layer (also referred to as an I-InP layer) is disposed below the n-InP layer, and has a large resistance value, so as to effectively prevent a current from flowing from the second p-electrode 1022 to the first laser 101.

The laser structure that this application embodiment provided is PIN knot. Where P refers to a P-type doped (e.g., P-InP) layer, I refers to an intrinsic indium phosphide layer, and n is an n-type doped (e.g., n-InP) layer. Wherein the resistance of the n-type doped layer is less than that of the p-type doped layer and less than that of the intrinsic indium phosphide layer. The second laser may include a cap layer which may include an n-InP layer which acts as the desired n-doped layer for the second laser and an I-InP layer which acts to prevent the second laser injection current from flowing to the first laser.

In some embodiments of the present application, each laser may include: n-pole and p-pole, and the n-electrodes of all the lasers in the semiconductor laser device are independent of each other, and the p-electrodes of all the lasers are independent of each other, for example, the first laser 101 includes: the first n-electrode 1011 and the first p-electrode 1012, the second laser 102 includes: the second n-electrode 1021 and the second p-electrode 1022, the first n-electrode 1011 and the second n-electrode 1021 are two completely different n-electrodes, and similarly, the first p-electrode 1012 and the second p-electrode 1022 are two completely different p-electrodes.

When the number of lasers in the semiconductor laser device is 3, 3 different n-electrodes and 3 different p-electrodes need to be provided in the semiconductor laser device. The case where the semiconductor laser device includes 4 lasers is similar to the case of 3 lasers, and is not illustrated one by one here.

Based on the first current path and the second current path shown in fig. 1, a first signal is injected from the first p-electrode 1012 to the first laser 101 and output from the first n-electrode 1011, and a second signal is injected from the second p-electrode 1022 to the second laser 102 and output from the second n-electrode 1021. Therefore, in the embodiment of the present application, the signal modulation of the first laser is not related to the second laser, so that the signal modulation of the first laser can be performed independently. Similarly, the second laser may be independently signal-modulated in this embodiment. If the number of the lasers in the semiconductor laser device is 3, the embodiment of the application can also perform independent signal modulation on the 3 lasers, so that the 3 lasers can be independently and optimally designed according to the characteristics of the lasers, and the performance index of the lasers can be improved.

In some embodiments of the present application, please refer to fig. 2, in which the first laser further includes: a first epitaxial region 1013, a first n-electrode 1011 and a first p-electrode 1012 located at both ends of the first epitaxial region 1013;

the second laser further comprises: a second epitaxial region 1023, a second n-electrode 1021 and a second p-electrode 1022 are positioned at both ends of the second epitaxial region 1023; second n-electrode 1021, second p-electrode 1022, and second epitaxial region 1023 are on the same side of cap layer 104;

the first and

second epitaxial regions

1013, 1023 are isolated from each other by the cap layer 104, and the first and

second epitaxial regions

1013, 1023 are located on either side of the cap layer 104.

The epitaxial region in the laser refers to a hierarchical structure generated by epitaxial growth on a substrate layer, and a material layer corresponding to different epitaxial materials can be generated when the epitaxial growth is performed by using the epitaxial materials in the laser. For example, when the epitaxial material is a semiconductor material, the epitaxial region generated may include: multiple Quantum Wells (MQWs), which may also be referred to simply as quantum wells. The epitaxial region in the embodiment of the present application refers to a general name of the internal material layer of the laser, and a specific hierarchical structure may be generated when a specific epitaxial material is used for epitaxial growth, which is described in detail in an example of a manufacturing method of the laser in the subsequent embodiment.

As shown in fig. 2, the second laser includes a cap layer 104, the first epitaxial region 1013 and the second epitaxial region 1023 are isolated from each other by the cap layer 104, and the first epitaxial region 1013 and the second epitaxial region 1023 are located on two sides of the cap layer 104, for example, in fig. 2, the first epitaxial region 1013 is located below the cap layer 104 and the second epitaxial region 1023 is located above the cap layer 104, so that the first laser and the second laser respectively form mutually isolated current channels. In addition, the cover layer 104 may provide the function of an n-type doped layer for the second laser, and the second n-electrode 1021, the second p-electrode 1022 and the second epitaxial region 1023 are located on the same side of the cover layer 104, so that a current channel generated on the second laser is isolated above the cover layer 104, so that the second laser may form a separate current channel.

In some embodiments of the present application, as shown in fig. 3, another schematic structural diagram of a semiconductor laser device provided in embodiments of the present application is shown. The first laser includes a first quantum well 4 (e.g., MQWs1 as shown in fig. 3) therein, e.g., the first epitaxial region includes: a first quantum well 4. The second laser comprises a second quantum well 11 (e.g. MQWs2 as shown in fig. 3), for example the second epitaxial region comprises a second quantum well, and both quantum wells may be formed simultaneously by a first epitaxial growth on a substrate layer when the semiconductor laser device is fabricated.

Further, the first quantum well 4 and the second quantum well 11 use different semiconductor materials. For example, Al is used for the first quantum well_0.105Ga_0.195In_0.7As material and Al As second quantum well_0.161Ga_0.102In_0.737As material, the material composition of the two quantum wells is different. Thus, the first quantum well 4 and the second quantum well 11 have different lasing wavelengths, for example, the lasing wavelength of the first quantum well 4 is around 1577nm and the lasing wavelength of the second quantum well 11 is around 1490 nm.

As shown in fig. 3, the first quantum well 4, the first p-electrode 7, the second n-electrode 9, the second quantum well 11, the second p-electrode 14, and the cap layer are all located above the substrate layer 2 (e.g., n-InP1 shown in fig. 3);

the first n electrode 1 is positioned below the substrate layer 2;

the first p-electrode 7 is located above the first quantum well 4;

the cover layer is positioned between the first quantum well 4 and the second quantum well 11;

the second n-electrode 9 is positioned below the second quantum well 11, and the second p-electrode 14 is positioned above the second quantum well 11;

the first p-electrode 7 and the second n-electrode 9 are separated by a capping layer;

the first p-electrode 7 and the second p-electrode 14 are separated by a capping layer, the second quantum well 11.

Wherein, as shown in fig. 3, the cap layer includes: an n-InP layer 8a and an I-InP layer 8b, the n-InP layer 8a being used to form the PIN structure of the second laser 102 and the I-InP layer 8b being used to increase electrical isolation. In fig. 3, the first n-electrode 1 is located below the substrate layer 2, the first p-electrode 7 and the second n-electrode 9 are separated by the cover layer, the first p-electrode 7 and the second p-electrode 14 are separated by the cover layer and the second quantum well 11, so that the first n-electrode of the first laser and the second n-electrode of the second laser are separated from each other, the first p-electrode of the first laser and the second p-electrode of the second laser are separated from each other, the first p-electrode of the first laser and the second n-electrode of the second laser are separated from each other, so that the first current path in the first laser and the second current path in the second laser are separated from each other, and in the embodiment of the present application, when a signal is applied to the electrode of each laser, since each laser can form a current path belonging to its own laser, each laser can carry out independent optimal design according to self characteristics, and no electric crosstalk exists between the two lasers, so that each laser can independently add a modulation signal, and the performance index of the laser is promoted.

Further, in some embodiments of the present application, a separate confinement layer (SCH) is included in the first laser and a separate confinement layer is included in the second laser. Specifically, a separate confinement layer is used for each of the upper and lower layers of the first quantum well in the first laser, and a separate confinement layer is used for each of the upper and lower layers of the second quantum well in the second laser. As shown in fig. 3, the first epitaxial region further includes: a first lower separation limiting layer 3, a first upper separation limiting layer 5; the second epitaxial region further includes: a second lower separation limiting layer 10, a second upper separation limiting layer 12; wherein,

a first lower separation confinement layer 3 is located between the substrate layer 1 and the first quantum well 4;

the first upper separation limiting layer 5 is positioned above the first quantum well 4 and below the cover layer;

a second lower separation confinement layer 10 is located between the cap layer and the second quantum well 11;

a second upper separation confinement layer 12 is located over the second quantum well 11.

In fig. 3, the upper and lower layers adjacent to the first quantum well 4 are separation limiting layers, the upper and lower layers adjacent to the second quantum well 11 are separation limiting layers, and the upper and lower separation limiting layers are defined as an upper separation limiting layer and a lower separation limiting layer, respectively, depending on the position distribution of the separation limiting layers in the laser. The separation limiting layer is used for enlarging the optical field distribution of the laser so as to reduce the optical field intensity of the quantum well region, further reduce the thermal effect of the device, enhance the limiting effect on electrons, and enable more carriers (electrons and holes) to be compounded in the quantum well (namely the active region) to generate photons.

Further, in some embodiments of the present application, a grating layer is included in the first laser, and a grating layer is also included in the second laser. The grating layer is used for manufacturing gratings in the laser, and the manufacturing process and technology of the gratings in the embodiment of the application are not described in detail.

As shown in fig. 3, the first epitaxial region further includes: a first grating layer 6 (e.g. grating layer 1 in fig. 3); the second epitaxial region further includes: a second grating layer 13 (e.g. grating layer 2 in fig. 3); wherein,

a first grating is manufactured on the first grating layer 6, and a second grating is manufactured on the second grating layer 13;

the first grating layer 6 is positioned above the first upper separation limiting layer 5;

the second grating layer 13 is located above the second upper separation limiting layer 12;

the cover layer is located above the first grating layer 6.

Wherein, as shown in fig. 3, the cap layer includes: an n-InP layer 8a and an I-InP layer 8b, the n-InP layer 8a being used to form the PIN structure of the second laser 102 and the I-InP layer 8b being used to increase electrical isolation. A first grating is formed on the first grating layer 6 shown in fig. 3, a second grating is formed on the second grating layer 13, and the first grating and the second grating are not shown in fig. 3, which is only described here and is not meant to limit the embodiments of the present application.

Further, in some embodiments of the present application, a contact layer is included in the first laser and a contact layer is also included in the second laser. The contact layer may be made of P-type indium phosphide (P-InP). A ridge waveguide may be etched in the contact layer. As shown in fig. 3, the first epitaxial region further includes: a first contact layer, the first contact layer comprising: a first ridge waveguide 16 a; the second epitaxial region further includes: a second contact layer, the second contact layer comprising: a second ridge waveguide 16 b;

the first contact layer is located between the first grating layer 6 and the first p-electrode 7;

the second contact layer is located between the second grating layer 13 and the second p-electrode 14.

In fig. 3, a P-InP material may be used for the contact layer, and a ridge waveguide may be etched on the contact layer, and the manufacturing process and technology of the ridge waveguide are not described in detail in this embodiment. The ridge waveguide is used for limiting an injection channel of laser current, and restraining the mode of the laser to ensure that the laser carries out single-mode lasing.

Further, in some embodiments of the present application, a silicon dioxide layer is included in the first laser and a silicon dioxide layer is also included in the second laser. Silicon dioxide is an insulating layer (also called a passivation layer) of the laser, and is mainly used to limit the current injection area. As shown in fig. 3, the first epitaxial region further includes: a first silicon dioxide layer 15 a; the second epitaxial region further includes: a second silicon oxide layer 15 b; wherein,

the first silicon dioxide layer 15a is located on the end face of the first ridge waveguide 16a, and the first silicon dioxide layer 15a is located between the first grating layer 6 and the first p-electrode 7;

the second silicon oxide layer 15b is located on the end face of the second ridge waveguide 16b, and the second silicon oxide layer 15b is located between the second grating layer 13 and the second p-electrode 14.

In which the silicon dioxide on top of the first ridge waveguide 16a and the second ridge waveguide 16b shown in fig. 3 is etched away, so that the first p-electrode 7 can be fabricated on top of the first ridge waveguide 16a and the second p-electrode 14 can be fabricated on top of the second ridge waveguide 16 b. In fig. 3, only the top of the first ridge waveguide 16a, the top of the second ridge waveguide 16b and the lower part of the second n-electrode 9 are not covered by silica, based on the distribution of silica described above, it can be ensured that the current injected from the second ridge waveguide 16b can only flow out from the second n-electrode 9, the current injected from the first ridge waveguide 16a can only flow out from the first n-electrode 1, and the first laser and the second laser can have mutually isolated current channels, so that the two lasers can independently add modulation signals.

In some embodiments of the present application, the first ridge waveguide 16a and the second ridge waveguide 16b have the same thickness;

the first ridge waveguide 16a is located at a lower lowest plane than the second ridge waveguide 16 b.

As shown in fig. 3, a first contact layer in the first laser and a second contact layer in the second laser are simultaneously grown, and ridge waveguide etching is performed on the first contact layer and the second contact layer, respectively, so as to form a first ridge waveguide of the first laser and a second ridge waveguide of the second laser. In addition, the first ridge waveguide and the ridge waveguide may have the same ridge waveguide width or different ridge waveguide widths, as long as the two ridge waveguides can ensure transverse mode lasing of the laser, and there is no strict limitation on the ridge waveguide width.

In some embodiments of the present application, the first ridge waveguide 16a and the second ridge waveguide 16b have the same thickness, and the two ridge waveguides are arranged in a staggered manner, and the lowest plane of the first ridge waveguide 16a is lower than that of the second ridge waveguide 16b, measured by the lowest plane of each ridge waveguide. In order to ensure the epitaxial quality of the two quantum wells, the growth of the two quantum wells is completed in one time of epitaxy, but the first laser only uses the first quantum well without using the second quantum well when working, and the second laser only uses the second quantum well without using the first quantum well when working. In the embodiment of the present application, a portion of the hierarchical structure related to the second quantum well is etched away in order to fabricate the first laser, which may result in the second ridge waveguide being higher than the first ridge waveguide, and finally forming a staggered-height device shape.

In some embodiments of the present application, the first laser and the second laser are in a side-by-side arrangement on the substrate layer.

The semiconductor laser device provided by the embodiment of the application is provided with at least two lasers, the lasers are all attached to the same substrate layer, and the plurality of lasers are arranged on the substrate layer side by side. The side-by-side arrangement is a distribution mode of a plurality of lasers on a substrate layer, and two lasers can be formed on the substrate layer side by side through two times of epitaxial growth.

In some embodiments of the present application, as shown in fig. 1 or fig. 2, the second laser 102 is superimposed on the first laser 101, and the first laser 101 is disposed on the substrate layer 103.

In the semiconductor laser device shown in fig. 3, two lasers are stacked. Two quantum wells (namely active regions) are arranged below the ridge waveguide of the second laser 102, only one quantum well (namely an active region) is arranged below the ridge waveguide of the first laser 101, the two lasers are not attached to the same substrate layer, the two lasers do not share other epitaxial region structures, and four electrodes of the two lasers are completely separated. The structure characteristics enable the semiconductor laser device to complete the growth of two quantum wells in one epitaxial growth, then etch a part of the quantum wells through selective etching, and manufacture the wide-wavelength-interval dual-wavelength laser by using different quantum wells, thereby reducing the epitaxial times, being beneficial to improving the performance index and the yield of the laser and reducing the manufacturing cost of the laser.

The foregoing embodiments describe the semiconductor laser device provided in the present application, and next, a method for manufacturing the semiconductor laser device is described, as shown in fig. 4, the method for manufacturing the semiconductor laser device provided in the embodiments of the present application includes the following steps:

401. and respectively manufacturing a first laser and a second laser on the same substrate layer, wherein the second laser comprises a cover layer, and a first current channel of the first laser and a second current channel of the second laser are mutually isolated through the cover layer.

In the embodiment of the application, the substrate layer can be made of an n-InP material, and a plurality of lasers in the semiconductor laser device can be commonly attached to the same substrate layer.

In the embodiment of the present application, a plurality of lasers may be fabricated on the same substrate layer, for example, when a semiconductor laser device includes three lasers, the structural feature between the two lasers still satisfies the constraint of the composition structure and the connection relationship of the two lasers shown in fig. 1, and in the subsequent embodiments, the semiconductor laser device includes two lasers for illustration, but the description is not limited to the composition structure of the semiconductor laser device provided in the embodiment of the present application.

In the embodiment of the application, a cover layer is arranged between the first laser and the second laser, and a first current channel of the first laser and a second current channel of the second laser are isolated from each other through the cover layer. In the case where each laser in the semiconductor laser device does not share an electrode, although a plurality of lasers in the semiconductor laser device are commonly attached to the same substrate layer, each laser may form a current path belonging to the respective laser. The current channel refers to a current generated in the laser when a signal is applied to an electrode of the laser, and the current moves in the laser to form a current channel. The isolation of the current paths of each laser from each other means that the charge movement in the different current paths is not affected by the charge movement in the other lasers. When applying signals on the electrode of each laser in the embodiment of the application, because each laser can form the current channel belonging to each laser, each laser can be independently and optimally designed according to the characteristics of the laser, no electric crosstalk exists between the two lasers, or the electric crosstalk between the two lasers is very small, and the performance indexes of the lasers are not influenced, therefore, each laser can independently add modulation signals, and the performance indexes of the lasers are promoted.

In some embodiments of the present application, step 401 manufactures a first laser and a second laser on the same substrate layer, respectively, including:

a1, performing first epitaxy on the front surface of the substrate layer, and growing a first epitaxial structure through the first epitaxy, wherein the first epitaxial structure comprises the following hierarchical structure from bottom to top: the laser comprises a first epitaxial region, a cover layer and a second epitaxial region, wherein the first epitaxial region belongs to a first laser, and the second epitaxial region belongs to a second laser;

a2, performing selective etching on the left side surface and the right side surface of the first epitaxial structure to obtain a second epitaxial structure;

and A3, performing selective etching on the right side surface of the second epitaxial structure to obtain a third epitaxial structure, wherein the cover layer on the right side surface of the third epitaxial structure is etched away, and the cover layer is remained on the left side surface of the third epitaxial structure.

Wherein, at first provide the substrate layer, then carry out epitaxy for the first time on the front of substrate layer, can use multiple epitaxial material at first time external delay, through first epitaxial growth first epitaxial structure, this first epitaxial structure from down up includes following hierarchical structure: the first epitaxial region, the cover layer and the second epitaxial region. The first epitaxial region belongs to the first laser, the second epitaxial region belongs to the second laser, the cover layer plays a role in isolating the first laser from the second laser, and the cover layer also plays a role in providing a substrate for the second laser.

After the first epitaxial structure is obtained, selective etching is performed on the left and right side surfaces of the first epitaxial structure, for example, the left and right ends of the second epitaxial region in the first epitaxial structure may be etched away, and at this time, the second epitaxial structure may be obtained. And then, carrying out second selective etching to etch the cover layer on the right side surface of the second epitaxial structure, thereby obtaining a third epitaxial structure. The third epitaxial structure has two end faces: a right side and a left side, the cap layer on the right side of the third epitaxial structure being etched away, the cap layer remaining on the left side of the third epitaxial structure.

402. The first laser and the second laser are provided with n-electrodes that are independent of each other, and the first laser and the second laser are provided with p-electrodes that are independent of each other.

In the embodiments of the present application, the first laser and the second laser are provided separately with electrodes belonging to the respective lasers, i.e. no electrode is shared between the different lasers.

Further, in some embodiments of the present application, in the implementation scenario of performing steps a1 to A3, step 402 configures independent n-electrodes for the first laser and the second laser, and independent p-electrodes for the first laser and the second laser, including:

b1, manufacturing a first p electrode above the first epitaxial region;

b2, manufacturing a second p electrode above the second epitaxial region;

b3, manufacturing a second n electrode on the cover layer on the left side face of the third epitaxial structure, wherein the second n electrode and the second p electrode belong to a second laser;

and B4, thinning the back surface of the substrate layer, and manufacturing a first n electrode on the back surface of the substrate layer, wherein the first n electrode and the first p electrode belong to the first laser.

As shown in fig. 3, the first n-electrode 1 is located below the substrate layer 2, the first p-electrode 7 and the second n-electrode 9 are separated by the cover layer, the first p-electrode 7 and the second p-electrode 14 are separated by the cover layer and the second quantum well 11, so that the first n-electrode of the first laser and the second n-electrode of the second laser are separated from each other, the first p-electrode of the first laser and the second p-electrode of the second laser are separated from each other, the first n-electrode of the first laser and the second p-electrode of the second laser are separated from each other, the first p-electrode of the first laser and the second n-electrode of the second laser are separated from each other, so that the first current path in the first laser and the second current path in the second laser are separated from each other, in the embodiment of the present application, when a signal is applied to the electrode of each laser, since each laser can form the current path of its own laser, each laser can carry out independent optimal design according to self characteristics, and no electric crosstalk exists between the two lasers, so that each laser can independently add a modulation signal, and the performance index of the laser is promoted.

In some embodiments of the present application, step 401 performs a first epitaxy on the front side of the substrate layer, and the step 401 may further include, in addition to the foregoing steps a1 to A3, by growing a first epitaxial structure by the first epitaxy:

a4, carrying out first epitaxial growth on the front surface of the substrate layer to respectively grow a first lower separation limiting layer, a first quantum well, a first upper separation limiting layer, a first grating layer, a cover layer, a second lower separation limiting layer, a second quantum well, a second upper separation limiting layer and a second grating layer; wherein,

the first lower separation limiting layer, the first quantum well, the first upper separation limiting layer and the first grating layer all belong to a first epitaxial region;

the second lower separation limiting layer, the second quantum well, the second upper separation limiting layer and the second grating layer all belong to a second epitaxial region.

In fig. 3, the upper and lower layers of the first quantum well are each a separation limiting layer, the upper and lower layers of the second quantum well are each a separation limiting layer, and the upper and lower separation limiting layers are defined as an upper separation limiting layer and a lower separation limiting layer according to the difference in the position distribution of the separation limiting layers in the laser.

Further, in some embodiments of the present application, after the step a4 is executed, the method for manufacturing a semiconductor laser device provided by the embodiments of the present application may further include the following steps:

a5, after growing a first grating layer on the first upper separation limiting layer, manufacturing a first grating on the first grating layer, wherein the first grating belongs to a first laser;

and A6, growing a second grating layer on the upper surface of the second upper separation limiting layer, and then manufacturing a second grating on the second grating layer, wherein the second grating belongs to a second laser.

A first grating is formed on the first grating layer 6 shown in fig. 3, a second grating is formed on the second grating layer 13, and the first grating and the second grating are not shown in fig. 3.

In some embodiments of the present application, after the step a3 performs selective etching on the right side surface of the second epitaxial structure to obtain a third epitaxial structure, the method for manufacturing a semiconductor laser device provided in the embodiments of the present application may further include the following steps:

a7, growing a protective layer on the cap layer on the left side of the third epitaxial structure.

The protective layer may be silicon dioxide, and the main function of the protective layer is to ensure that the portion for manufacturing the second n electrode is not grown with a P-InP layer in the secondary epitaxy process.

In some embodiments of the present application, after the step a7 grows the protective layer on the cap layer on the left side of the third epitaxial structure, the method for manufacturing the semiconductor laser device provided by the embodiment of the present application may further include the following steps:

a8, performing secondary epitaxy on the first grating layer and the second grating layer respectively, growing a first contact layer on the first grating layer through the secondary epitaxy, and growing a second contact layer on the second grating layer;

a9, etching a first ridge waveguide from the first contact layer, and etching a second ridge waveguide from the second contact layer, wherein the first ridge waveguide belongs to the first epitaxial region, and the second ridge waveguide belongs to the second epitaxial region; wherein,

the first contact layer is positioned between the first grating layer and the first p electrode;

the second contact layer is located between the second grating layer and the second p-electrode.

In the embodiment of the present application, the method for manufacturing the semiconductor laser device only needs to perform two times of epitaxial growth, the first time of epitaxial growth is described in detail in the foregoing steps a1 to a7, and the second time of epitaxial growth is described in step A8. Through the second epitaxy, a first contact layer and a second contact layer can be grown, the contact layer can be made of P-InP materials, ridge waveguides can be etched on the contact layer, and the manufacturing process and the technology of the ridge waveguides are not described in detail in the embodiment of the application.

In some embodiments of the present application, after the step a9 etches a first ridge waveguide from the first contact layer and a second ridge waveguide from the second contact layer, the method for manufacturing a semiconductor laser device provided by the embodiments of the present application may further include the following steps:

a10, growing a first silicon dioxide layer on the first grating layer and the first ridge waveguide, and growing a second silicon dioxide layer on the second grating layer and the second ridge waveguide; wherein,

the first silicon dioxide layer belongs to the first epitaxial region, and the second silicon dioxide layer belongs to the second epitaxial region.

The first laser comprises a silicon dioxide layer, and the second laser also comprises a silicon dioxide layer. Silicon dioxide is an insulating layer (also called a passivation layer) of the laser, and is mainly used to limit the current injection area.

Further, in some embodiments of the present application, after the step a10 grows the first silicon dioxide layer on the first grating layer and the first ridge waveguide, and grows the second silicon dioxide layer on the second grating layer and the second ridge waveguide, the method for manufacturing the semiconductor laser device provided by the embodiment of the present application may further include the following steps:

a11, cleaning the protective layer from the cover layer on the left side surface of the third epitaxial structure;

a12, etching away the first silicon dioxide layer on top of the first ridge waveguide, and etching away the second silicon dioxide layer on top of the second ridge waveguide.

In which the silicon dioxide on top of the first ridge waveguide 16a and the second ridge waveguide 16b shown in fig. 3 is etched away, so that the first p-electrode 7 can be fabricated on top of the first ridge waveguide 16a and the second p-electrode 14 can be fabricated on top of the second ridge waveguide 16 b. In fig. 3, only the top of the first ridge waveguide 16a, the top of the second ridge waveguide 16b and the lower part of the second n-electrode 9 are not covered by silica, so that the silica distribution ensures that the current injected into the second ridge waveguide 16b can only flow out from the second n-electrode 9, and the current injected into the first ridge waveguide 16a can only flow out from the first n-electrode 1, so that the first laser and the second laser can have mutually isolated current channels, and the two lasers can independently add modulation signals.

In some embodiments of the present application, the first p-electrode is located over the first silicon dioxide layer and over a top of the first ridge waveguide; the second p-electrode is located over the second silicon dioxide layer and over a top of the second ridge waveguide.

After windowing the silicon dioxide layer, the silicon dioxide on the tops of the two ridge waveguides can be etched away, and a P electrode is added above the silicon dioxide layer, so that a current channel can be established between the P electrode and a hierarchical structure in the laser.

In order to better understand and implement the above-described scheme of the embodiments of the present application, the following description specifically illustrates a corresponding application scenario.

In order to make the objects, technical solutions and advantages of the embodiments of the present application more clearly understood, the embodiments of the present application are described in further detail below with reference to the accompanying drawings and the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the embodiments of the application and are not intended to limit the embodiments of the application.

The embodiment of the application provides a 1490nm and 1577nm dual-wavelength laser. The dual-wavelength laser is internally provided with two lasers, each laser comprises a ridge waveguide, two groups of quantum wells are arranged below one ridge waveguide, and only one group of quantum wells is arranged below the other ridge waveguide; the four electrodes of the two lasers are completely separated, and each laser can independently add a modulation signal. The dual-wavelength laser provided by the embodiment of the application not only can realize wide-interval dual-wavelength lasing, but also can realize independent tuning of two wavelengths, and has the advantages of compact structure and low cost.

In the embodiment of the present application, the emission wavelength of the dual-wavelength laser may be 1490nm and 1577nm, and is also applicable to other wavelengths, for example, any interval in the 1200-1700nm band may use the design scheme of the dual-wavelength laser provided in the embodiment of the present application, but when the wavelength interval is small (for example, less than 20nm), the same quantum well is used to implement fabrication of different wavelengths, and it is not necessary to use the structure of the dual laser.

The structure of a 1490nm and 1577nm dual wavelength laser is described with reference to fig. 3, which is a cross-sectional view of the laser shown in fig. 3. The dual wavelength laser device comprises from bottom to top in sequence: a first n-electrode 1, a substrate layer 2(n-InP1), a first lower confinement layer 3(SCH1), a multiple quantum well 14(MQWs 1), a first upper confinement layer 5(SCH2), a first grating layer 6 (grating layer 1), a first p-electrode 7, a cap layer (e.g., comprising n-InP28a and I-InP8b), a second n-electrode 9, a second lower confinement layer 10(SCH3), a second active region 11(MQWs 2), a second upper confinement layer 12(SCH4), a second grating layer 13 (grating layer 2), a second p-electrode 14, a silicon dioxide layer (comprising 15a and 15b in fig. 3), a contact layer (comprising 16a and 16b in fig. 3).

The cover layer may include an n-InP layer and an I-InP layer, the cover layer and the upper layers 9-14, 15b, and 16b together form a complete second laser structure, the lower layers 1-7, 15a, and 16a together form a complete first laser structure, and the two lasers are attached to the same substrate layer n-InP 1. The current generated by the second signal is injected from the second ridge waveguide (W2) and finally flows out from the second n-electrode 9 through the cover layer without passing through the No. 1-6 epitaxial region below, and similarly, the current generated by the first signal is injected from the first ridge waveguide (W1) and finally flows out from the first n-electrode 1 through the substrate layer 2, so that the first laser and the second laser respectively have mutually isolated current channels.

The left hand laser shown in fig. 3 is the second laser and may include structures numbered 8-14, 15b, 16b, and the right hand laser shown in fig. 3 is the first laser and may include structures numbered 1-7, 15a, 16 a. Wherein the right side 15a and the left side 15b in fig. 3 are grown together, the second laser has structures 1-6 below, but the second laser operates independently of the first laser, which only functions as a carrying platform. Likewise, the first laser operates independently of the second laser.

In the present embodiment, the four electrodes of the two lasers are completely separated, the second n-electrode 9 and the second p-electrode 14 together form the electrodes required for the second active region 11(MQWs 2), and the first n-electrode 1 and the first p-electrode 7 together form the electrodes required for the first active region 4(MQWs 1). Each laser can independently add modulation signals without crosstalk.

Wherein silicon dioxide is an insulating layer (also called passivation layer) mainly used to confine the current injection region, only above the ridge waveguide (W1, W2) and below the second n-electrode 9 are not covered by silicon dioxide. Such a distribution of silicon dioxide ensures that the current injected at W2 can only flow from the second n-electrode 9 and the current injected at W1 can only flow from the first n-electrode 1.

In the embodiment of the present application, the widths of the two ridge waveguides are W1 and W2, respectively, and the distance between the two ridge waveguides can be adjusted according to actual requirements and process conditions. From the cross-sectional view shown in fig. 3, it can be seen that two active regions (MQWs 1 and MQWs2) exist below one ridge waveguide, only one active region (MQWs 1) exists below the other ridge waveguide, the lasing wavelengths of different active regions are different, the lasing wavelength of the active region (i.e., quantum well) is related to the material composition of the active region, and in the dual-wavelength laser structure provided in the embodiment of the present application, the two quantum wells adopt different material compositions, so that different lasing wavelengths can be realized.

In the embodiment of the present application, the two lasers can be independently signal-modulated, which is determined by the overall design structure, the cap layer includes an n-InP layer and an I-InP layer, and forms a complete laser structure together with the above reference numbers 9-14, 15b, and 16b, and current is injected from the second ridge waveguide (W2) and finally flows out from the second n electrode 9 through the cap layer. This current does not pass through the underlying epitaxial region nos. 1-6, also independent of the right first ridge waveguide (W1), the second p-electrode 7. The first n electrode 1, the epitaxial region 2-6, the second p electrode 7 and the first ridge waveguide (W1) form a complete laser structure, and current is injected from the first ridge waveguide (W1) to pass through the epitaxial region 6-2 and finally flows out of the first n electrode 1. The current circulation paths of the two lasers do not overlap with each other, so that crosstalk does not exist between the current circulation paths, and modulation signals can be added independently.

As can be known from the above illustration of the dual-wavelength laser, two lasers that the dual-wavelength laser includes in the embodiment of the present application do not share other epitaxial region structures except attaching to the same substrate, so that two lasers can carry out independent optimal design according to their characteristics, and the performance index of the laser is promoted.

It should be noted that both lasers are grown on the same substrate layer 2, and the cap layer 8 includes: an n-InP layer and an I-InP layer. The n-InP layer may be used to form a PIN junction of the second laser, and an undoped I-InP layer is disposed below the n-InP layer, which has a relatively high resistance and effectively prevents a current from flowing from the second p-electrode 1022 to the first laser 101.

The following is an example of a method for manufacturing a dual-wavelength laser, for example, a method for manufacturing a dual-wavelength laser with 1490nm and 1577nm may mainly include the following steps:

step S1, performing primary epitaxy, and growing two groups of quantum wells, an upper separation limiting layer, a lower separation limiting layer and a grating layer on the substrate, wherein the upper separation limiting layer, the lower separation limiting layer and the grating layer are required by the dual-wavelength laser;

step S2, selective area etching, wherein the selective area is etched to an n-InP layer close to MQWs 2;

step S3, further selecting area etching, and etching off the n-InP layer on one side;

step S4, manufacturing gratings aiming at the two groups of quantum wells;

step S5, secondary epitaxial growth of a contact layer;

and step S6, finishing ridge etching and windowing of the laser, and manufacturing four electrodes of the dual-wavelength laser.

Specifically, please refer to fig. 5a to 5g in the manufacturing process from step S1 to step S6.

Referring to fig. 5a, firstly, an epitaxy is performed on an n-InP substrate, and the epitaxial material includes a first lower confinement layer 3(SCH1), a first active region 4(MQWs 1), a first upper confinement layer 5(SCH2), a first grating layer 6 (grating layer 1), a cap layer (n-InP28a and I-InP8b), a second n-electrode 9, a second lower confinement layer 10(SCH3), a second active region 11(MQWs 2), a second upper confinement layer 12(SCH4), and a second grating layer 13 (grating layer 2).

The epitaxial region of the selected area is then etched to the cap layer using a selective etching technique, as shown in figure 5 b.

As shown in fig. 5c, a second selective etching is then performed to etch away the cap layer on one side.

As shown in fig. 5d, a protective layer, typically silicon dioxide, is next grown on the cap layer, the main function of this protective layer being to ensure that the left part for making the second n-electrode 9 is not grown with a P-InP layer during the second epitaxy. A grating suitable for the first active region (MQWs 1) is fabricated on the first grating layer 6 (grating layer 1), and a grating suitable for the second active region (MQWs 2) is fabricated on the second grating layer 13 (grating layer 2).

After the wafer is cleaned, selective epitaxy is performed to grow an upper contact layer of P-InP in the regions other than the n-InP cap layer, as shown in fig. 5 e. The contact layer P-InP is grown on the upper surfaces of the gratings 1 and 2, only on the gratings 1 and 2, and the cap layers (n-InP and I-InP) are not grown on the regions because of the protective layers.

The ridge waveguides of both lasers are next etched and a silicon dioxide layer 15 is grown over the entire wafer, as shown in figure 5 f.

As shown in fig. 5g, a windowing operation is then performed to etch away the silicon dioxide on top of the two ridge waveguides and clean the protective layer from the cap layer.

As shown in fig. 3, finally, a first p electrode 7, a second n electrode 9 and a second p electrode 14 are manufactured on the front surface of the wafer, then the n-InP substrate layer 2 is thinned, and finally, a first n electrode 1 is manufactured on the back surface of the substrate layer 2. The n-InP substrate layer 2 is thinned, the first n electrode is manufactured after the thinned n-InP substrate, a wafer process can be adopted, the wafer is finally cleaved into one laser, the cleavage is difficult for the excessively thick substrate, and the cleavage precision and the requirements can be met only by thinning the substrate.

This application embodiment has accomplished the preparation of wide interval dual wavelength laser through twice epitaxial growth on same substrate, and two dual wavelength laser arrange side by side and the height is straggly, in order to guarantee the epitaxial quality of two quantum wells, just accomplished the growth of two quantum wells at an epitaxy time, but left side laser during operation has only used quantum well 2, and right side during operation has only used quantum well 1. The right side laser is fabricated by etching away the portion associated with the quantum well 2, and therefore is shorter than the left side ridge waveguide, resulting in a staggered shape that is not the same height. Two active regions are arranged below one laser ridge waveguide, only one active region is arranged below one laser, the two lasers do not share other epitaxial region structures except that the two lasers are attached to the same substrate, and four electrodes of the two lasers are completely separated. The dual-wavelength laser can complete the growth of two active regions in one epitaxial growth, part of the active regions are etched by selective etching, and the dual-wavelength laser with wide wavelength intervals is manufactured by using different active regions, so that the epitaxial frequency is reduced, the performance index and the yield of the laser are improved, and the manufacturing cost of the laser is reduced. Four completely separated electrodes ensure that the two lasers can work independently and add modulation signals. The two lasers do not share other epitaxial regions except the substrate, so that the design of the two lasers can be independently optimized, and the performance indexes of the lasers are improved.

The above description is only a specific implementation of the embodiments of the present application, and is not intended to limit the embodiments of the present application. The embodiments of the present application can be used for all dual wavelength laser designs, not just limited to the communication band. The wavelength range in the embodiment of the present application is arbitrary wavelength interval within 1200-1600nm, and if other substrates are used, all the wavelength bands that can be grown by other substrates can be covered.

It should be noted that the semiconductor laser device provided in the embodiments of the present application is also applicable to multi-wavelength lasers, such as lasers with three or four active regions, for example, multi-wavelength lasers with wavelength coverage range between 1200 nm and 1600 nm.

It should be noted that for simplicity of description, the foregoing methods are described as a series of acts or combination of acts, but those skilled in the art will recognize that the present application is not limited by the order of acts, as some steps may occur in other orders or concurrently depending on the application. Further, those skilled in the art should also appreciate that the embodiments described in the specification are preferred embodiments and that the acts and modules referred to are not necessarily required in this application.

It should be noted that the above-described embodiments of the apparatus are merely schematic, where the units described as separate parts may or may not be physically separate, and the parts shown as units may or may not be physical units, may be located in one place, or may be distributed on multiple units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.

Claims

A semiconductor laser device, comprising: a first laser and a second laser, wherein,

the first laser and the second laser are attached to the same substrate layer;

the n-electrode of the first laser and the n-electrode of the second laser are independent of each other, and the p-electrode of the first laser and the p-electrode of the second laser are independent of each other;

when a first signal is added to an electrode of the first laser, a current generated in the first laser forms a first current channel, when a second signal is added to an electrode of the second laser, a current generated in the second laser forms a second current channel, and the modulation of the first laser by the first signal and the modulation of the second laser by the second signal are independent of each other;

the second laser includes a cap layer for achieving mutual isolation between the first current path and the second current path.
The semiconductor laser device according to claim 1, wherein the first laser comprises: a first n-electrode and a first p-electrode;

the second laser includes: a second n-electrode and a second p-electrode;

the first signal is injected from the first p-electrode to the first laser and output from the first n-electrode;

the second signal is injected from the second p-electrode to the second laser and output from the second n-electrode.
The semiconductor laser device according to claim 2, wherein the first laser further comprises: the first n electrode and the first p electrode are positioned at two ends of the first epitaxial region;

the second laser further comprises: a second epitaxial region, the second n-electrode and the second p-electrode being located at both ends of the second epitaxial region; the second n-electrode, the second p-electrode and the second epitaxial region are located on the same side of the cap layer;

the first epitaxial region and the second epitaxial region are isolated from each other through the cover layer, and the first epitaxial region and the second epitaxial region are located on two sides of the cover layer.
A semiconductor laser device as claimed in claim 3, wherein the first epitaxial region comprises: a first quantum well; the second epitaxial region includes: a second quantum well, the first quantum well and the second quantum well being formed by the same epitaxial growth;

the first quantum well, the first p-electrode, the second n-electrode, the second quantum well, the second p-electrode, and the cap layer are all located above the substrate layer;

the first n electrode is positioned below the substrate layer;

the first p-electrode is positioned above the first quantum well;

the cap layer is located between the first quantum well and the second quantum well;

the second n-electrode is positioned below the second quantum well, and the second p-electrode is positioned above the second quantum well;

the first p-electrode and the second n-electrode are separated by the capping layer;

the first p-electrode and the second p-electrode are separated by the cover layer and the second quantum well.
The semiconductor laser device of claim 4, wherein the first epitaxial region further comprises: a first lower separation limiting layer, a first upper separation limiting layer; the second epitaxial region further comprises: a second lower separation limiting layer, a second upper separation limiting layer; wherein,

the first lower separation confinement layer is located between the substrate layer and the first quantum well;

the first upper separation confinement layer is located above the first quantum well and below the cap layer;

the second lower separation confinement layer is located between the cap layer and the second quantum well;

the second upper separation confinement layer is located above the second quantum well.
The semiconductor laser device of claim 5, wherein the first epitaxial region further comprises: a first grating layer; the second epitaxial region further comprises: a second grating layer; wherein,

a first grating is manufactured on the first grating layer, and a second grating is manufactured on the second grating layer;

the first grating layer is positioned above the first upper separation limiting layer;

the second grating layer is positioned above the second upper separation limiting layer;

the cover layer is located above the first grating layer.
The semiconductor laser device of claim 6, wherein the first epitaxial region further comprises: a first contact layer, the first contact layer comprising: a first ridge waveguide;

the second epitaxial region further comprises: a second contact layer, the second contact layer comprising: a second ridge waveguide;

the first contact layer is located between the first grating layer and the first p-electrode;

the second contact layer is located between the second grating layer and the second p-electrode.
The semiconductor laser device of claim 7, wherein the first epitaxial region further comprises: a first silicon dioxide layer; the second epitaxial region further comprises: a second silicon dioxide layer; wherein,

the first silicon dioxide layer is positioned on the end face of the first ridge waveguide and is positioned between the first grating layer and the first p electrode;

the second silicon dioxide layer is located on an end face of the second ridge waveguide, and the second silicon dioxide layer is located between the second grating layer and the second p-electrode.
The semiconductor laser device according to claim 7, wherein the first ridge waveguide and the second ridge waveguide have the same thickness;

the lowest plane where the first ridge waveguide is located is lower than the lowest plane where the second ridge waveguide is located.
A semiconductor laser device as claimed in any one of claims 1 to 9, characterized in that the first laser and the second laser are arranged side by side on the substrate layer.
A semiconductor laser device as claimed in any one of claims 1 to 10, characterized in that the second laser is superimposed on the first laser and the first laser is arranged on the substrate layer.
A multi-wavelength laser, comprising: a semiconductor laser device as claimed in any one of claims 1 to 10.
A semiconductor chip, comprising: a semiconductor laser device as claimed in any one of claims 1 to 10.
A light module, characterized in that the light module comprises: a semiconductor laser device as claimed in any one of claims 1 to 10.
An optical line terminal, characterized in that the optical line terminal comprises: a light module as claimed in claim 14.
An optical network unit, comprising: the optical module of claim 14.
A method of manufacturing a semiconductor laser device, the method comprising:

respectively manufacturing a first laser and a second laser on the same substrate layer, wherein the second laser comprises a cover layer, and a first current channel of the first laser and a second current channel of the second laser are isolated from each other through the cover layer;

the first laser and the second laser are provided with n-electrodes that are independent of each other, and the first laser and the second laser are provided with p-electrodes that are independent of each other.
The method of claim 17, wherein fabricating the first laser and the second laser on the same substrate layer, respectively, comprises:

carry out epitaxy for the first time on the front of substrate layer, through epitaxial growth goes out first epitaxial structure for the first time, first epitaxial structure is from up including following hierarchical structure down: the laser comprises a first epitaxial region, a cover layer and a second epitaxial region, wherein the first epitaxial region belongs to the first laser, and the second epitaxial region belongs to the second laser;

carrying out selective etching on the left side surface and the right side surface of the first epitaxial structure to obtain a second epitaxial structure;

and carrying out selective etching on the right side surface of the second epitaxial structure to obtain a third epitaxial structure, wherein the cover layer on the right side surface of the third epitaxial structure is etched, and the cover layer is reserved on the left side surface of the third epitaxial structure.
The method of claim 18, wherein configuring the first laser and the second laser with n-electrodes and the first laser and the second laser with p-electrodes independent of each other comprises:

manufacturing a first p electrode above the first epitaxial region;

manufacturing a second p electrode above the second epitaxial region;

manufacturing a second n electrode on the cover layer on the left side surface of the third epitaxial structure, wherein the second n electrode and the second p electrode belong to the second laser;

and thinning the back surface of the substrate layer, and manufacturing a first n electrode on the back surface of the substrate layer, wherein the first n electrode and the first p electrode belong to the first laser.
The method of claim 19, wherein said performing a first epitaxy on the front side of the substrate layer by which a first epitaxial structure is grown further comprises:

carrying out first epitaxial growth on the front surface of the substrate layer to respectively grow a first lower separation limiting layer, a first quantum well, a first upper separation limiting layer, a first grating layer, the cover layer, a second lower separation limiting layer, a second quantum well, a second upper separation limiting layer and a second grating layer; wherein,

the first lower separation confinement layer, the first quantum well, the first upper separation confinement layer and the first grating layer all belong to the first epitaxial region;

the second lower confinement layer, the second quantum well, the second upper confinement layer, and the second grating layer all belong to the second epitaxial region.