A monolithic integrated light emitting chip and its manufacturing method

Abstract

The present application discloses a monolithic integrated optical transmitter chip and a method for manufacturing the same, relating to the technical field of semiconductor devices. The chip comprises a substrate, a passive waveguide layer, a first laser layer, a second laser layer, a modulator layer, a cladding layer, and a contact layer. The passive waveguide layer is formed by etching according to a predetermined pattern and comprises two input branches and one output branch. The first laser layer is disposed on one of the input branches, and the second laser layer and the modulator layer are disposed on the other optical signal input branch. The paths of the two input branches are coupled to the paths of the output branches. Gratings are disposed on the two laser layers, and the cladding layer and the contact layer are disposed above these functional layers. The present application integrates two different laser layers in the chip, and combines the optical signals emitted by the different laser layers for output through a passive waveguide layer with a predetermined pattern. The technical solution of the present application effectively reduces the cost of the optical transmitter module, reduces power consumption, and improves product reliability.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor devices, and in particular to a monolithic integrated light emitting chip and a method for manufacturing the same. Background Art

[0002] Passive optical networks (PON) are the future direction of access network development. This is primarily due to the bandwidth they provide, which can meet the needs of various broadband services now and in the future, making them widely favored solutions for broadband access. Furthermore, they offer relatively low costs, both in terms of equipment costs and operational and maintenance overhead. Comprehensive economic and technical analysis indicates that PON is the primary technology for implementing fiber-to-the-building (FTTB) and fiber-to-the-home (FTTH) deployments.

[0003] In order to achieve a smooth evolution of a large number of Gigabit Passive Optical Networks (GPON) in the existing network to 10G Passive Optical Networks (XGPON), the industry has proposed a combined passive optical network solution (Combo PON). This solution integrates two generations of PON into a single board and optical module to achieve compatibility between the two PON technologies, such as compatibility between GPON and XG-PON, and compatibility between GPON and symmetric 10G Passive Optical Network (XGS-PON). Currently, in the Combo PON solution, the two light source devices used for GPON and 10G GPON are combined into a dual-channel in one optical module and output from the same optical port. Figure 4 As shown in the figure, since the light source devices of the two wavelengths need to be manufactured independently, and the technology and process required to package and integrate the light source devices of the two wavelengths λ1 and λ2 in the same optical module for combined output are relatively complex, the cost of the Combo PON optical transmitter module is relatively high. This is specifically reflected in the difficulty in coupling the independently manufactured light source devices and the high precision required for welding. The coupling structure needs to be precisely designed during the manufacturing process to improve the combining effect, and high-precision welding is required during integration to ensure the product yield. In addition, the use of discrete devices also leads to high power consumption and poor reliability of the module, and large loss of the optical fiber used to transmit the optical signal. These problems have limited the widespread use of Combo PON. Summary of the Invention

[0004] The purpose of this application is to provide a monolithic integrated optical transmitter chip and its preparation method for Combo PON, integrating two different laser layers in the chip and combining the optical signals emitted by the different laser layers through a passive waveguide layer with a predetermined pattern to output the combined optical signals, thereby reducing manufacturing costs, reducing power consumption, and improving product reliability.

[0005] The technical solution of the present application is to provide a method for manufacturing a monolithic integrated light emitting chip, the method comprising:

[0006] Step 1: Prepare a substrate, grow a passive waveguide material on the substrate, and etch the passive waveguide material layer according to a predetermined pattern to form a passive waveguide layer, wherein the passive waveguide layer includes a first input branch, a second input branch, and an output branch, wherein a first laser region and a first amplifier region are divided in the region where the first input branch is located, a second laser region, a modulator region, and a second amplifier region are divided in the region where the second input branch is located, and a third amplifier region is divided in the region where the output branch is located;

[0007] Step 2: growing a short-wavelength quantum well material layer at least in the region where the first input branch is located, and selectively removing the short-wavelength quantum well material in regions other than the first laser region and the first amplifier region to form a first laser layer and a first amplifier layer;

[0008] Step 3: forming a pair of selective area epitaxial growth masks with a specific spacing on both sides of the second laser region and the second amplifier region, respectively, and then growing a long-wavelength quantum well material layer at least in the region where the second input branch and the output branch are located, and selectively removing the long-wavelength quantum well material in the region other than the second laser region, the modulator region, the second amplifier region, and the third amplifier region, to form a second laser layer, a modulator layer, a second amplifier layer, and a third amplifier layer;

[0009] Step 4, forming a first grating layer and a second grating layer on the first laser layer and the second laser layer respectively;

[0010] In step 5, cladding layers and contact layers are grown on each functional layer from bottom to top, and the contact layers in areas other than the laser area, amplifier area, and modulator area are covered with a mask, and the cladding layers and contact layers in uncovered areas are p-doped.

[0011] Furthermore, step 1 also includes:

[0012] A buffer layer is grown on the substrate, and the buffer layer is located between the passive waveguide layer and the substrate.

[0013] Furthermore, the length of the selective area epitaxial mask pairs on both sides of the second laser region is the same as the length of the second laser region, the length of the selective area epitaxial mask pairs on both sides of the second amplifier region is the same as the length of the second amplifier region, and the specific spacing between the two pairs of selective area epitaxial mask pairs meets the condition: the emission wavelength of the modulator layer and the third amplifier layer is 30 to 100 nm shorter than the emission wavelength of the second laser layer and the second amplifier layer.

[0014] Furthermore, the preparation method further comprises: selectively removing the contact layer in areas other than the areas where the laser layer, the amplifier layer and the modulator layer are located.

[0015] Furthermore, the first laser layer uses a short-wavelength quantum well material InGaAsP or InGaAlAs with a bandgap wavelength of 1450 to 1510 nm;

[0016] The second laser layer uses a long wavelength quantum well material InGaAsP or InGaAlAs, with a band gap wavelength of 1450 to 1510 nm;

[0017] The bandgap wavelength of the passive waveguide layer is 1100 nm to 1400 nm;

[0018] The Bragg wavelength of the first grating layer is 1450 to 1510 nm, and the Bragg wavelength of the second grating layer is 1530 to 1580 nm.

[0019] The present application also provides a monolithic integrated light emitting chip manufactured using the method for manufacturing a monolithic integrated light emitting chip, the monolithic integrated light emitting chip comprising:

[0020] The monolithic integrated light emitting chip comprises: a substrate, a passive waveguide layer, a first laser layer, a first grating layer, a second laser layer, a second grating layer, a modulator layer, a cladding layer and a contact layer;

[0021] The passive waveguide layer is formed by etching a passive waveguide layer material grown on the entire surface of the substrate according to a predetermined pattern, and the passive waveguide layer includes a first input branch, a second input branch, and an output branch, wherein the first input branch and the second input branch are commonly coupled to the output branch;

[0022] The first laser layer is arranged on the first input branch and is located at an end away from the coupling position, and the first grating layer is arranged on the first laser layer;

[0023] A second laser layer is provided in a selective growth region defined by the first mask pair on the second input branch, the second laser layer is located at an end away from the coupling position, and a second grating layer is provided on the second laser layer;

[0024] The modulator layer is arranged on the second input branch and is located between the position where the second laser layer is located and the coupling position;

[0025] The cladding layer and the contact layer are sequentially arranged on top of each functional layer from bottom to top.

[0026] Furthermore, the monolithic integrated light emitting chip further includes a first amplifier layer, a second amplifier layer, and a third amplifier layer;

[0027] The first amplifier layer is provided on the first input branch and is located between the position where the first laser layer is located and the coupling position, and is used for amplifying the optical signal generated by the first laser layer;

[0028] The second amplifier layer is provided in a selective growth region defined by the second mask pair on the second input branch and is located between the position where the modulator layer is located and the coupling position, and is used to amplify the modulated optical signal of the second laser layer. The width of the region where the second amplifier layer is located is limited by the second mask pair with a specific spacing.

[0029] The third amplifier layer is arranged on the output branch, and is used to amplify the optical signals coupled from the two input branches to the output branch.

[0030] Further, the length of the first mask pair is the same as the length of the second laser layer, and the length of the second mask pair is the same as the length of the second amplifier layer;

[0031] The modulator layer is located between the area where the second laser layer is located and the area where the second amplifier layer is located;

[0032] The light emission wavelengths of the modulator layer and the third amplifier layer are shorter than the light emission wavelengths of the second laser layer and the second amplifier layer.

[0033] Further, the cladding includes a doped portion and an undoped portion;

[0034] The doped part is located above the first grating layer, the second grating layer, the modulator layer, the first amplifier layer, the second amplifier layer and the third amplifier layer. The doped part is formed by p-type doping. The undoped part is located above the passive waveguide layer. The contact layer is arranged above the doped part.

[0035] Furthermore, the monolithic integrated light emitting chip further includes a buffer layer, which is arranged between the substrate and the passive waveguide layer.

[0036] The beneficial effects of this application are:

[0037] The technical solution in the present application utilizes monolithic integration technology to fabricate lasers of different emission wavelengths for GPON and XGPON on the same substrate, and combines the optical signals emitted by different lasers for output through a passive waveguide layer with a specific pattern. Compared with the prior art method of packaging and integrating independently manufactured light source devices of different wavelengths into the same optical module and then combining and outputting them, the technical solution in the present application directly uses a passive waveguide layer with a specific pattern for combining, eliminating the steps of precisely designing the coupling structure for discrete devices in the optical module and performing high-precision welding during subsequent packaging and integration, which can effectively reduce the production cost of the Combo PON optical transmitter module. Moreover, the technical solution in the present application is an integrated design with rigorous process. Compared with the prior art design that requires assembly, it has higher reliability and yield, and avoids connection problems, material mismatch and other problems that occur during the assembly and integration process.

[0038] The technical solution in this application uses a passive waveguide layer to achieve combined output, which reduces power consumption compared to the existing technology of using optical fiber and a combiner for combined output. The technical solution in this application also performs p-type doping on the cladding and contact layers and removes the contact layer above the passive waveguide layer, further reducing waveguide transmission losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The advantages of the above and / or additional aspects of the present application will become apparent and readily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0040] Figure 1 is a schematic structural diagram of the passive waveguide layer of the monolithically integrated light emitting chip according to the present application;

[0041] Figure 2 is a schematic cross-sectional structural diagram of the first laser layer of the monolithically integrated light emitting chip according to the present application;

[0042] Figure 3 is a schematic cross-sectional structural diagram of the second laser layer of the monolithically integrated light emitting chip according to the present application;

[0043] Figure 4 This is a partial structural diagram of an optical module compatible with two generations of PON in the prior art;

[0044] Among them, 10-substrate, 20-buffer layer, 30-passive waveguide layer, 40-first laser layer, 41-first grating layer, 50-second laser layer, 51-second grating layer, 60-modulator layer, 71-first amplifier layer, 72-second amplifier layer, 73-third amplifier layer, 80-cladding, 81-doped part, 82-undoped part, 90-contact layer, 100-first mask pair, 200-second mask pair. DETAILED DESCRIPTION

[0045] In order to more clearly understand the above-mentioned objectives, features and advantages of the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features therein can be combined with each other in the absence of conflict.

[0046] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0047] Taking the InP-based material system as an example, a monolithic integrated light emitting chip and a manufacturing method thereof in an embodiment of the present invention are generally introduced below.

[0048] like Figures 1 to 3As shown, this embodiment provides a monolithic integrated light emitting chip, which includes a substrate 10, a passive waveguide layer 30, a first laser layer 40, a first grating layer 41, a second laser layer 50, a second grating layer 51, a modulator layer 60, a cladding layer 80 and a contact layer 90.

[0049] The passive waveguide layer 30 is formed by etching a passive waveguide layer material grown on the entire surface of the substrate 10 according to a predetermined pattern. The area where the passive waveguide layer 30 is located is a passive waveguide region (WG). The passive waveguide layer 30 includes a first input branch, a second input branch, and an output branch. The first input branch and the second input branch are optical signal input branches, and the output branch is an optical signal output branch. The first input branch and the second input branch are coupled to the output branch. The location where the first input branch, the second input branch, and the output branch are connected is a coupling location.

[0050] The first laser layer 40 is disposed on the first input branch of the passive waveguide layer 30 and is located at an end of the input branch away from the coupling position. The region where the first laser layer 40 is located is a first laser block (DFB1). The first grating layer 41 is disposed on the first laser layer 40. The first input branch is used to receive the optical signal emitted by the first laser layer 40. The second input branch is used to receive the optical signal emitted by the second laser layer 50.

[0051] The second laser layer 50 is arranged in a selective growth region of a specific pitch on the second input branch limited by the first mask pair 100 (SAG mask) (that is, it is arranged on the second input branch by adjusting the width of the intermediate selective growth region using the mask pair). The second laser layer 50 is located at an end of the second input branch away from the coupling position. The region where the second laser layer 50 is located is the second laser block (DFB2). The second grating layer 51 is arranged on the second laser layer 50. The length of the first mask pair 100 is the same as the length of the second laser layer 50.

[0052] The modulator layer 60 is arranged on the second input branch of the second laser layer 50 and is adjacent to the second laser layer 50. The modulator layer 60 is located between the position where the second laser layer 50 is located and the coupling position. The area where the modulator layer 60 is located is the modulator area (EAM). The emission wavelength of the modulator layer 60 is 30nm to 100nm shorter than the emission wavelength of the second laser layer 50.

[0053] The first grating layer 41 and the second grating layer 51 can be uniform periodic gratings, and phase-shift structures can also be introduced therein. The Bragg wavelength of the first grating layer 41 is 1450 to 1510 nm, and the Bragg wavelength of the second grating layer 51 is 1530 to 1580 nm. In this embodiment, the first grating layer 41 can be formed on the first laser layer 40, and the second grating layer 51 can be formed on the second laser layer 50 by etching.

[0054] The passive waveguide layer 30 can be made of InGaAsP, with a thickness of 200 to 800 nm and a bandgap wavelength of 1100 to 1400 nm. The first laser layer 40 can be made of short-wavelength quantum well materials such as InGaAsP (indium gallium arsenic phosphide) or InGaAlAs (indium gallium aluminum arsenic), with a bandgap wavelength of 1450 to 1510 nm. The second laser layer 50 can be made of long-wavelength quantum well materials such as InGaAsP or InGaAlAs, with a bandgap wavelength of 1530 to 1580 nm. The substrate 10 can be an InP substrate.

[0055] The first mask pair 100 is a selective area epitaxial mask pair, and silicon oxide material or silicon nitride material can be selected. After the first mask pair 100 is set in the second laser region, the long wavelength quantum well material of the second laser layer 50 can only grow in an area of a specific width in the middle position of the first mask pair 100, and will not grow in the area covered by the mask. By adjusting the spacing of the first mask pair 100, the width of the second laser layer 50 can be controlled, thereby adjusting the emission wavelength of the second laser layer 50.

[0056] The monolithic integrated light emitting chip further includes a first amplifier layer 71 , a second amplifier layer 72 and a third amplifier layer 73 .

[0057] The first amplifier layer 71 is disposed on the first input branch and is located above the passive waveguide layer 30 between the first laser layer 40 and the coupling position. The first amplifier layer 71 is located close to the first laser layer 40 and is used to amplify the optical signal generated by the first laser layer 40. The area where the first amplifier layer 71 is located is the first amplifier area (SOA1).

[0058] The second amplifier layer 72 is disposed in a selective growth region of a specific width on the second input branch, defined by the second mask pair 200. The second amplifier layer 72 is located above the passive waveguide layer 30 between the location of the modulator layer 60 and the coupling location, that is, on the side of the modulator layer 60 away from the second laser layer 50. The second amplifier layer 72 is located close to the modulator layer 60 and is used to amplify the optical signal modulated by the modulator layer 60. The region where the second amplifier layer 72 is located is the second amplifier area (SOA2). The length of the second mask pair 200 is the same as the length of the second amplifier layer 72.

[0059] The third amplifier layer 73 is provided on the output branch of the passive waveguide layer 30 and is used to amplify the optical signal coupled from the two optical signal input branches to the optical signal output branch. The region where the third amplifier layer 73 is located is the third amplifier area (SOA3). The emission wavelength of the third amplifier layer 73 and the modulator layer 60 is 30 to 100 nm shorter than the emission wavelength of the second laser layer 50 and the second amplifier layer 72.

[0060] First amplifier layer 71 can be made of short-wavelength quantum well materials such as InGaAsP or InGaAlAs, with a bandgap wavelength of 1450 to 1510 nm. Second amplifier layer 72 and third amplifier layer 73 can be made of long-wavelength quantum well materials such as InGaAsP or InGaAlAs, with a bandgap wavelength of 1530 to 1580 nm. Second mask pair 200 is also a selective area epitaxy mask pair and can be made of silicon oxide or silicon nitride.

[0061] The cladding 80 is arranged above each functional layer, which includes the first grating layer 41, the second grating layer 51, the modulator layer 60, the first amplifier layer 71, the second amplifier layer 72, the third amplifier layer 73 and a portion of the passive waveguide layer 30. The cladding 80 can be formed by etching the cladding material grown on the entire surface of the substrate 10 according to a predetermined pattern. That is, after etching, the cladding material above each functional layer forms the cladding 80. The cladding 80 includes a doped portion 81 and an undoped portion 82.

[0062] The doped portion 81 is located above the first grating layer 41, the second grating layer 51, the modulator layer 60, the first amplifier layer 71, the second amplifier layer 72, and the third amplifier layer 73. The doped portion 81 is formed by performing p-type doping on the cladding 80 in the area where these functional layers are located. The undoped portion 82 is arranged above the passive waveguide layer 30 outside the area where the first grating layer 41, the second grating layer 51, the modulator layer 60, the first amplifier layer 71, the second amplifier layer 72, and the third amplifier layer 73 are located. The undoped portion 82 is the undoped portion of the cladding 80.

[0063] The contact layer 90 is disposed on the doped portion 81 and is a p-type doped contact layer 90. The contact layer 90 can be formed by etching the contact layer material grown on the entire surface of the substrate 10 according to a predetermined pattern, that is, the contact material in the area where the doped portion 81 is located is etched to form the contact layer 90.

[0064] The cladding layer 80 can be made of undoped InP material, and the contact layer 90 can be made of undoped InGaAs material. In this embodiment, the cladding layer 70 and contact layer 80 can be disposed in corresponding areas by etching, and portions of the cladding layer 80 and contact layer 90 can be doped using Zn extension doping technology. The mask material can be SiO2. Specifically, a SiO2 mask can be used to cover the cladding layer 80 and contact layer 90 outside the areas where the first grating layer 41, the second grating layer 51, the first amplifier layer 71, the second amplifier layer 72, and the third amplifier layer 73 are located. P-type doping can be performed using the Zn extension doping technology. After the p-type doping is completed, the mask is removed. The areas covered by the mask are undoped, which can reduce waveguide transmission loss. The contact layer 90 is not disposed above the cladding layer 80 outside the areas where the first grating layer 41, the second grating layer 51, the modulator layer 60, the first amplifier layer 71, the second amplifier layer 72, and the third amplifier layer 73 are located. This is to reduce waveguide transmission loss.

[0065] The monolithic integrated light emitting chip also includes a buffer layer 20. The buffer layer 20 is disposed between the substrate 10 and the passive waveguide layer 30 to alleviate lattice mismatch between the substrate 10 and the functional layer, reducing stress and fabrication defects. The buffer layer 20 can be made of InP.

[0066] This embodiment also provides a method for manufacturing a monolithic integrated light emitting chip, the method comprising:

[0067] Step 1: Prepare a substrate 10, sequentially grow a buffer layer 20 and a passive waveguide material on the substrate 10, and etch the passive waveguide material layer according to a predetermined pattern to form a passive waveguide layer 30. The passive waveguide layer 30 includes a first input branch, a second input branch, and an output branch. The region where the first input branch is located is divided into a first laser region and a first amplifier region. The region where the second input branch is located is divided into a second laser region, a modulator region, and a second amplifier region. The region where the output branch is located is divided into a third amplifier region.

[0068] Step 2: growing a short-wavelength quantum well material layer at least in the region where the first input branch is located, and selectively removing the short-wavelength quantum well material in regions other than the first laser region and the first amplifier region. The short-wavelength quantum well material in the first laser region forms the first laser layer 40, and the short-wavelength quantum well material in the first amplifier region forms the first amplifier layer 71.

[0069] In step 3, a pair of selective epitaxial mask layers with a specific spacing are formed on both sides of the second input branch of the second laser region and the second amplifier region, respectively. Then, a long-wavelength quantum well material layer is grown at least in the region where the second input branch and the output branch are located. The long-wavelength quantum well material in regions other than the second laser region, the modulator region, the second amplifier region, and the third amplifier region is selectively removed to form the second laser layer 50, the modulator layer 60, the second amplifier layer 72, and the third amplifier layer 73. The length of the selective epitaxial mask pair for the second laser region is the same as that of the second laser region, and the length of the selective epitaxial mask pair for the second amplifier region is the same as that of the second amplifier region. The specific spacing between the selective epitaxial mask pairs for the two regions satisfies the condition that the emission wavelengths of the modulator layer 60 and the third amplifier layer 73 are 30 to 100 nm shorter than the emission wavelength of the second laser layer 50.

[0070] Step 4: forming a first grating layer 41 and a second grating layer 51 on the first laser layer 40 and the second laser layer 50 respectively;

[0071] In step 5, undoped cladding layers 80 and contact layers 90 are grown on each functional layer from bottom to top, and a mask is used to cover areas other than the laser area, amplifier area, and modulator area. The cladding layers 80 and contact layers 90 in uncovered areas are p-doped, and the contact layers 90 in areas other than the laser area, amplifier area, and modulator area are selectively removed.

[0072] In this embodiment, in order not to affect the function of the passive waveguide layer 30, it is necessary to etch the passive waveguide material layer according to a predetermined pattern after growing the passive waveguide material layer to form a passive waveguide layer 30 including two input branches and one output branch, so that the passive waveguide layer 30 can couple the optical signal to the output branch through the two input branches to achieve the function of combining. Taking a Y-shaped pattern as an example, a gap of 3-6 μm can be set around the Y-shaped passive waveguide area by etching during operation, and the passive waveguide material layer in the Y-shaped passive waveguide area serves as the passive waveguide layer 30.

[0073] Taking the InP-based material system as an example, the substrate 10 is an InP substrate, the buffer layer 20 is an InP buffer layer material, the passive waveguide layer 30 is an InGaAsP material, the first laser layer 40 and the first amplifier layer 71 are short-wavelength quantum well materials InGaAsP or InGaAlAs, and the band gap wavelength is controlled between 1450 and 1510 nm by adjusting the ratio of elements. The second laser layer 50, the modulator layer 60, the second amplifier layer 72 and the third amplifier layer 73 are long-wavelength quantum well materials InGaAsP or InGaAlAs By adjusting the ratio of elements, the band gap wavelength is controlled between 1530 and 1580 nm. The first grating layer 41 and the second grating layer 51 use uniform periodic gratings or gratings with phase shift structures. The Bragg wavelength of the first grating layer 41 is adjusted to between 1450 and 1510 nm, and the Bragg wavelength of the second grating layer 51 is adjusted to between 1530 and 1580 nm. The cladding layer 80 uses InP cladding material, the contact layer 90 uses InGaAs contact layer material, and the selective area epitaxial mask and other masks use silicon oxide material or silicon nitride material, such as SiO2 film.

[0074] The specific production method is:

[0075] First, an InP buffer layer material and a passive waveguide layer material are sequentially grown on the entire surface of a cleaned InP substrate. The thickness of the passive waveguide layer material is between 200 and 800 nm. The passive waveguide layer material is etched according to a predetermined pattern of a WG region to form a passive waveguide layer 30 including a first input branch, a second input branch, and an output branch. The WG region is divided into a DFB1 region, a DFB2 region, an EAM region, a SOA1 region, a SOA2 region, and a SOA3 region. A short-wavelength quantum well material is grown on the first input branch. The short-wavelength quantum well material in the DFB1 region and the SOA1 region is retained, and the short-wavelength quantum well material in other regions is removed. The material in the DFB1 region is used as the first laser layer 40, and the material in the SOA1 region is used as the first amplifier layer 71.

[0076] In this embodiment, molecular beam epitaxy (MBE) or metal-organic chemical vapor deposition (MOCVD) can be used to grow the various functional layers on the InP substrate. Growth can be performed either entirely or locally. After growth is complete, the material affecting the functional layers in other areas can be removed by etching. To ensure that the passive waveguide material layer in the passive waveguide region does not affect its functionality, the passive waveguide material layer is etched according to a predetermined pattern, leaving a gap of 3-6 μm around the passive waveguide region.

[0077] Then, a first mask pair 100 with a specific spacing is fabricated on both sides of the passive waveguide layer 30 in the DFB2 region, and a second mask pair 200 with a specific spacing is fabricated on both sides of the passive waveguide layer 30 in the SOA2 region. After the mask pair fabrication is completed, long-wavelength quantum well material is grown on the second input branch and the output branch. The long-wavelength quantum well material in the DFB2 region, the EAM region, the SOA2 region, and the SOA3 region is retained, while the long-wavelength quantum well material in other regions is removed. The long-wavelength quantum well material in the DFB2 region, the EAM region, the SOA2 region, and the SOA3 region is sequentially used as the second laser layer 50, the modulator layer 60, the second amplifier layer 72, and the third amplifier layer 73. Due to the specific spacing between the first mask pair 100 and the second mask pair 200, the emission wavelengths of the modulator layer 60 and the third amplifier layer 73 are 30 nm to 100 nm shorter than the emission wavelengths of the second laser layer 50 and the second amplifier layer 72.

[0078] In this embodiment, when fabricating a selective area epitaxial mask pair with a specific pitch in the DFB2 region and the SOA2 region, the specific range of the specific pitch can be determined by simulation or experiment before fabrication in order to better control the emission wavelength of the functional layer.

[0079] A first grating layer 41 is fabricated on the first laser layer 40, and a second grating layer 51 is fabricated on the second laser layer 50. The laser layer and the grating layer form a resonant cavity structure. The grating layer can provide Bragg reflection at a wavelength corresponding to the grating period, thereby forming a feedback mechanism. This mechanism causes photons (the photons are spontaneously radiated by the material itself. When an external driving current enters the quantum well material, the quantum well material generates electrons and holes that recombine, and thus spontaneously radiate photons) to reflect back and forth within the resonant cavity, forming laser oscillation at a specific wavelength, thereby generating an optical signal output.

[0080] Finally, undoped InP cladding material and InGaAs contact layer material are sequentially grown above each functional layer to form a cladding layer 80 and a contact layer 90. A SiO2 film is used to cover the contact layer 90 in areas other than the DFB1, DFB2, EAM, SOA1, SOA2, and SOA3 regions. The cladding 80 and contact layer 90 in the uncovered areas are p-doped using Zn extended doping technology. After doping is completed, the SiO2 film is removed. Due to the covering effect of the SiO2 film, the cladding 80 above the passive waveguide layer 30 is an undoped portion 82, which can reduce waveguide transmission loss. The contact layer 90 above the passive waveguide layer 30 is selectively removed to reduce waveguide transmission loss.

[0081] In this embodiment, the first laser layer 40 and the first grating layer 41 form a first laser. No modulator layer is provided on the first input branch. The first laser can be a directly modulated laser. During operation, an external modulation signal can be added to the drive current to modulate the light intensity of the first laser. The second laser layer 50 and the second grating layer 51 form a second laser. During operation, the drive current of the second laser remains unchanged, and the optical signal generated by the second laser is externally modulated by the modulator layer 60. The modulator layer 60 is an electro-absorption modulator (EAM). When a voltage is applied from an external power source, an electric field is generated within the modulator layer 60, which changes the absorption properties of the material itself. The electro-absorption effect of the material is utilized to modulate the optical signal. Specifically, the electric field increases the absorption coefficient of the modulator layer material. When the optical signal passes through the modulator layer, some of the light is absorbed, resulting in a decrease in the intensity of the optical signal. The absorption coefficient of the modulator layer is controlled by adjusting the applied voltage, thereby dynamically modulating the intensity of the optical signal.

[0082] The first input branch and the second input branch of the passive waveguide layer 30 form a combiner at the coupling position. The light emitted by the first laser layer 40 and the second laser layer 50 is combined by the combiner and then enters the output branch. In this embodiment, the combiner formed by the passive waveguide layer 30 can be a Y-waveguide, an MMI coupler, or a directional coupler.

[0083] The first amplifier layer 71 and the second amplifier layer 72 are used to amplify the light emitted by the first laser layer 40 and the second laser layer 50, respectively, before combining the light. The third amplifier layer 73 is used to amplify the combined optical signal. After external current is injected, the amplifier layer forms a high density of electrons and holes. When the light signal passes through the amplifier layer, it induces electrons and holes to recombine, generating more photons. These new photons increase the intensity of the light signal, thereby achieving amplification. The amplified light signal continues to transmit through the passive waveguide layer and is ultimately output.

[0084] Example: InGaAsP is selected as the short-wavelength quantum well material with an element ratio of 0.55:0.45:0.3:0.7. InGaAsP is selected as the long-wavelength quantum well material with an element ratio of 0.75:0.25:0.93:0.07. After chip fabrication, the emission wavelength of the first laser is detected to be approximately 1480 nm, and the emission wavelength of the second laser is approximately 1550 nm. When a drive current of 100 mA is applied, the power of the first input branch optical signal is 30 mW, the power of the second input branch optical signal is 28 mW, and the combined power is 55 mW, meeting the design requirements of this example.

[0085] The steps in this application can be adjusted in order, combined, and deleted according to actual needs.

[0086] The units in the device of the present application can be combined, divided and deleted according to actual needs.

[0087] Although the present application is disclosed in detail with reference to the accompanying drawings, it should be understood that these descriptions are merely exemplary and are not intended to limit the application of the present application. The scope of protection of the present application is defined by the appended claims and may include various modifications, alterations and equivalents made to the invention without departing from the scope and spirit of the present application.

Claims

1. A method for preparing a monolithic integrated light emitting chip, characterized in that: The preparation method comprises: Step 1, preparing a substrate (10), growing a passive waveguide material on the substrate (10), and etching the passive waveguide material layer according to a predetermined pattern to form a passive waveguide layer (30), wherein the passive waveguide layer (30) includes a first input branch, a second input branch, and an output branch, dividing a first laser region and a first amplifier region in the region where the first input branch is located, dividing a second laser region, a modulator region, and a second amplifier region in the region where the second input branch is located, and dividing a third amplifier region in the region where the output branch is located; Step 2: growing a short-wavelength quantum well material layer at least in the region where the first input branch is located, and selectively removing the short-wavelength quantum well material in other regions except the first laser region and the first amplifier region to form a first laser layer (40) and a first amplifier layer (71); Step 3, respectively making a pair of selective area epitaxial masks with a specific spacing on both sides of the second laser region and the second amplifier region, then growing a long wavelength quantum well material layer at least in the region where the second input branch and the output branch are located, selectively removing the long wavelength quantum well material in other regions except the second laser region, the modulator region, the second amplifier region and the third amplifier region, to form a second laser layer (50), a modulator layer (60), a second amplifier layer (72) and a third amplifier layer (73); The length of the selective epitaxial mask pairs on both sides of the second laser region is the same as the length of the second laser region, the length of the selective epitaxial mask pairs on both sides of the second amplifier region is the same as the length of the second amplifier region, and the specific spacing between the two pairs of selective epitaxial mask pairs satisfies the condition that the light emission wavelength of the modulator layer (60) and the third amplifier layer (73) is 30 to 100 nm shorter than the light emission wavelength of the second laser layer (50) and the second amplifier layer (72); Step 4, forming a first grating layer (41) and a second grating layer (51) on the first laser layer (40) and the second laser layer (50), respectively; Step 5: growing a cladding layer (80) and a contact layer (90) on each functional layer from bottom to top, using a mask to cover the contact layer (90) in other areas except the laser area, the amplifier area and the modulator area, and performing p-type doping on the cladding layer (80) and the contact layer (90) in the uncovered area.

2. The method for preparing a monolithic integrated light emitting chip according to claim 1, wherein: The step 1 further comprises: A buffer layer (20) is grown on the substrate (10), and the buffer layer (20) is located between the passive waveguide layer (30) and the substrate (10).

3. The method for preparing a monolithic integrated light emitting chip according to claim 1, wherein: The preparation method further comprises: selectively removing the contact layer (90) in areas other than the areas where the laser layer, the amplifier layer and the modulator layer (60) are located.

4. The method for preparing a monolithic integrated light emitting chip according to claim 1, wherein: The first laser layer (40) uses a short-wavelength quantum well material InGaAsP or InGaAlAs, with a band gap wavelength of 1450 to 1510 nm; The second laser layer (50) uses a long wavelength quantum well material InGaAsP or InGaAlAs, and the band gap wavelength is 1450 to 1510 nm; The band gap wavelength of the passive waveguide layer (30) is 1100 nm to 1400 nm; The Bragg wavelength of the first grating layer (41) is 1450 to 1510 nm, and the Bragg wavelength of the second grating layer (51) is 1530 to 1580 nm.

5. A monolithic integrated light emitting chip manufactured by the method for manufacturing a monolithic integrated light emitting chip according to any one of claims 1 to 4, characterized in that: The monolithic integrated light emitting chip comprises: a substrate (10), a passive waveguide layer (30), a first laser layer (40), a first grating layer (41), a second laser layer (50), a second grating layer (51), a modulator layer (60), a cladding layer (80), and a contact layer (90); The passive waveguide layer (30) is formed by etching a passive waveguide layer material grown on the entire surface of the substrate (10) according to a predetermined pattern, and the passive waveguide layer (30) includes a first input branch, a second input branch, and an output branch, wherein the first input branch and the second input branch are coupled to the output branch. The first laser layer (40) is arranged on the first input branch and is located at an end away from the coupling position, and the first grating layer (41) is arranged on the first laser layer (40); A second laser layer (50) is arranged in a selective growth region defined by a first mask pair (100) on a second input branch, the second laser layer (50) is located at an end away from a coupling position, and a second grating layer (51) is arranged on the second laser layer (50); The modulator layer (60) is arranged on the second input branch and is located between the position where the second laser layer (50) is located and the coupling position; The cladding layer (80) and the contact layer (90) are sequentially arranged above each functional layer from bottom to top.

6. The monolithic integrated light emitting chip according to claim 5, wherein: The monolithic integrated light emitting chip further comprises a first amplifier layer (71), a second amplifier layer (72) and a third amplifier layer (73); The first amplifier layer (71) is arranged on the first input branch and is located between the position of the first laser layer (40) and the coupling position, and is used to amplify the optical signal generated by the first laser layer (40); The second amplifier layer (72) is arranged in a selective growth area defined by the second mask pair (200) on the second input branch and is located between the position of the modulator layer (60) and the coupling position, and is used to amplify the modulated optical signal of the second laser layer (50). The width of the area where the second amplifier layer (72) is located is limited by the second mask pair (200) with a specific spacing; The third amplifier layer (73) is arranged on the output branch and is used to amplify the optical signal coupled from the two input branches to the output branch.

7. The monolithic integrated light emitting chip according to claim 6, wherein: The length of the first mask pair (100) is the same as the length of the second laser layer (50), and the length of the second mask pair (200) is the same as the length of the second amplifier layer (72); The modulator layer (60) is located between the area where the second laser layer (50) is located and the area where the second amplifier layer (72) is located; The light emission wavelengths of the modulator layer (60) and the third amplifier layer (73) are shorter than the light emission wavelengths of the second laser layer (50) and the second amplifier layer (72).

8. The monolithic integrated light emitting chip according to claim 6, wherein: The cladding (80) includes a doped portion (81) and an undoped portion (82); The doped portion (81) is located above the first grating layer (41), the second grating layer (51), the modulator layer (60), the first amplifier layer (71), the second amplifier layer (72), and the third amplifier layer (73); the doped portion (81) is formed by p-type doping; the undoped portion (82) is located above the passive waveguide layer (30); and the contact layer (90) is provided above the doped portion (81).

9. The monolithic integrated light emitting chip according to claim 5, wherein: The monolithic integrated light emitting chip further comprises a buffer layer (20), and the buffer layer (20) is arranged between the substrate (10) and the passive waveguide layer (30).

Images