A method for manufacturing an array laser

Abstract

The application discloses a preparation method of an array laser, and relates to the technical field of semiconductor optoelectronic integrated devices. The method comprises the following steps: dividing a plurality of unit laser areas on a substrate; growing active and passive materials in the unit laser areas through a selective epitaxy and etching process to form a gain layer and a grating layer; preparing a uniform grating in the grating area; integrally growing a cover layer and a contact layer and etching to form a shallow ridge waveguide structure; etching a cantilever beam structure comprising a cantilever arm and an air slot on the grating layer below the shallow ridge waveguide structure to realize thermal isolation and local tuning; and finally preparing P-face electrodes, heating electrodes and N-face electrodes to construct a complete electrically-driven and thermally-tuned array laser. The application effectively eliminates the thermal crosstalk between the laser units in the array laser, realizes wavelength independence and precise control, improves the overall wavelength stability of the array, reduces the thermal action volume through the low-heat-capacity cantilever arm structure, and significantly reduces the tuning power consumption.

Description

Technical Field

[0001] This invention relates to the technical field of semiconductor optoelectronic integrated devices, and more specifically, to a method for fabricating an array laser. Background Technology

[0002] In optical communication, arrayed wavelength tunable lasers enhance system performance and flexibility through multi-wavelength coordination and dynamic tuning capabilities. For example, a quad-array laser can simultaneously output four independent wavelengths, enabling parallel transmission across multiple channels to meet the demands of ultra-high-speed optical networks. Through electrical or thermal tuning mechanisms, a single device can replace traditional fixed-wavelength laser arrays, dynamically allocating wavelengths and reducing the complexity and cost of multi-wavelength light sources.

[0003] However, in the existing technical solutions, the main problems to achieve multi-wavelength array integration are as follows: (1) For the discrete assembly scheme, each tunable laser is fabricated separately, and then multiple independent tunable laser chips are integrated on the same carrier board by physical mounting. Although this method achieves natural thermal insulation in physical terms and the channels do not interfere with each other, its disadvantages are that the package size is huge, the optical path coupling process is extremely complex, and the performance consistency between chips is difficult to guarantee during the manufacturing process, which cannot meet the development trend of miniaturization and high integration of optical communication devices; (2) For the traditional monolithic integration scheme, the scheme integrates four lasers on the same indium phosphide (InP) substrate. Although it improves the integration and reduces the coupling difficulty, during the thermal tuning process, the semiconductor substrate, as an excellent thermal conductor, will cause serious thermal crosstalk. If the thermal tuning mechanism is adopted, when each laser is thermally tuned, the entire area where it is located needs to be heated. A large amount of heat is lost to the substrate, causing the wavelength of the adjacent lasers to drift, which seriously affects the accuracy of independent control of each channel. At the same time, due to the great heat sink effect of the substrate, maintaining wavelength stability requires a lot of additional power consumption, which limits the application of the device in low power scenarios.

[0004] Therefore, how to effectively solve inter-channel thermal interference and reduce tuning power consumption while maintaining the advantages of monolithic integration is a key technical problem that urgently needs to be solved in the field of high-performance array lasers. Summary of the Invention

[0005] The purpose of this invention is to provide a method for fabricating an array laser, which solves the technical problems of complex processes for fabricating individual tunable lasers, difficulty in ensuring performance consistency between chips, high power consumption, severe thermal crosstalk between adjacent lasers, and unstable wavelength in traditional monolithic integrated tunable laser arrays during thermal tuning.

[0006] The technical solution of the present invention is: to provide a method for fabricating an array laser, the method comprising:

[0007] Step 1: Prepare a substrate. Divide a predetermined number of unit laser regions on the substrate according to a preset arrangement direction, and divide the gain region, phase region and grating region into each unit laser region in sequence.

[0008] Step 2: Grow active material on the substrate, cover the gain region in each unit laser region with a silicon dioxide thin film, and then selectively remove the active material in other regions outside the gain region to form a gain layer in each unit laser region.

[0009] Step 3: For each unit laser region, passive material is grown by docking in its corresponding region consisting of phase region and grating region, the silicon dioxide film is removed, and a uniform grating is made on top of the passive material within the grating region to form a grating layer in each unit laser region.

[0010] Step 4: A capping layer and a contact layer are grown sequentially from bottom to top above all unit laser regions. For each unit laser region, the capping layer and the contact layer are etched as a whole according to a predetermined ridge pattern to form a shallow ridge waveguide structure. The shallow ridge waveguide structure is laterally distributed in the center of the entire functional layer composed of a gain layer, a phase region passive material layer and a grating layer.

[0011] Step 5: For each unit laser region, the grating layer is etched according to a predetermined cantilever beam pattern to form a cantilever beam structure, which includes a cantilever arm located directly below the shallow ridge waveguide structure and air slots symmetrically distributed on both sides.

[0012] Step 6: Fabricate P-side electrodes above the contact layers corresponding to the gain region and phase region, respectively; fabricate heating electrodes above the contact layers corresponding to the grating region; and fabricate N-side electrodes below the substrate.

[0013] Furthermore, the layout of each unit laser region is the same. For any unit laser region, the gain region, phase region, and grating region are arranged sequentially and adjacent regions are closely connected.

[0014] Furthermore, step 2 specifically includes:

[0015] Active materials are grown layer by layer from bottom to top on the substrate. A silicon dioxide thin film is used to cover the gain region in each unit laser region. Then, the active materials in other regions outside the gain region are removed by dry etching, and the active materials remaining after etching are removed by wet etching with sulfuric acid solution to form a gain layer in each unit laser region. The gain layer includes a lower confinement layer, a multiple quantum well layer and an upper confinement layer from bottom to top.

[0016] Furthermore, step 3 is followed by the following steps:

[0017] All unit laser regions are covered with a silicon dioxide film. Passive materials in areas other than the individual unit laser regions on the substrate are selectively removed. Finally, the silicon dioxide film is removed.

[0018] Furthermore, step 4 specifically includes:

[0019] A capping layer material and a contact layer material are grown sequentially from bottom to top over the entire substrate. A silicon dioxide film is used to cover all unit laser areas. The capping layer material and contact layer material in areas other than the individual unit laser areas on the substrate are selectively removed, and then the silicon dioxide film is removed.

[0020] Furthermore, step 4 also includes:

[0021] For each unit laser region, a transverse strip mask is first fabricated at the center of the contact layer. Then, the capping layer and contact layer in this unit laser region are etched using SiCl4 gas dry etching to form a shallow ridge structure. The etching depth is controlled within the range of the capping layer and contact layer, and does not penetrate the capping layer to the material layer below it. Then, the two sides of the shallow ridge structure are modified by wet etching with HCl solution to finally form an inverted shallow ridge waveguide structure that conforms to the predetermined ridge pattern. The transverse strip mask is then removed.

[0022] Furthermore, step 4 is followed by the following steps:

[0023] For each unit laser region, electrically isolated trenches are etched on the contact layers between the gain region and the phase region, and between the phase region and the grating region, respectively, so that electrical isolation is formed between the gain layer, the passive material layer of the phase region, and the grating layer.

[0024] Furthermore, step 5 specifically includes:

[0025] First, two strip regions corresponding to air slots are divided on the upper surface of the grating layer corresponding to each unit laser region. The two strip regions are symmetrically distributed on both sides of the shallow ridge waveguide structure and are arranged parallel to the shallow ridge waveguide structure. Then, a mask with a cantilever strip pattern is fabricated on the entire substrate using photolithography. This mask covers all areas on the entire substrate except for the areas where all air slots are located. The passive material in all areas except the areas corresponding to the air slots is removed using reactive ion etching equipment and hydrobromic acid etching. The etching depth is controlled within the grating layer and does not penetrate the grating layer to the substrate below it, so as to form a cantilever beam structure consisting of a central cantilever arm and symmetrical air slots on both sides in each unit laser region. The width of the upper surface of the cantilever arm is greater than the width of the lower surface of the shallow ridge waveguide structure.

[0026] Furthermore, step 6 specifically includes:

[0027] A silicon nitride thin film is grown above each unit laser region. Then, P-plane electrodes are fabricated above the contact layers corresponding to the gain region and phase region, respectively. A heating electrode is fabricated above the contact layer corresponding to the grating region using titanium-platinum material. The middle part of the heating electrode is located above the shallow ridge waveguide structure corresponding to the grating region, and the two ends of the heating electrode are positive and negative electrodes. Finally, the substrate is thinned and N-plane electrodes are fabricated on the entire surface.

[0028] The beneficial effects of this invention are:

[0029] First, the technical solution of this invention introduces a cantilever beam in each laser unit of the array laser and etches air grooves on both sides of the cantilever arm to form a locally suspended thermal isolation structure. This physically isolates the grating tuning regions corresponding to each laser in terms of thermal performance, limiting the diffusion of tuning heat to adjacent channels and the substrate. This significantly reduces thermal coupling between laser units and avoids wavelength drift of neighboring lasers during single-channel heating, thereby effectively eliminating thermal crosstalk between channels. This enables independent and precise control of multi-channel wavelengths, improving the overall wavelength stability and channel isolation of the array. Simultaneously, the technical solution of this invention reduces the thermally affected volume through the low-thermal-capacity cantilever arm structure, concentrating the heat generated by the heating electrodes on the grating region, achieving higher electrothermal conversion efficiency. This allows for fast and sensitive wavelength tuning with a smaller drive current, significantly reducing tuning power consumption. Furthermore, the cantilever beam and air groove structure in each laser unit also weakens the impact of substrate heat sink effects on the tuning region, reducing the continuous compensation power required to maintain the target wavelength and further reducing power consumption to meet the application requirements of low-power, high-density optical communication systems.

[0030] The technical solution in this invention combines a cantilever beam thermal insulation design within a monolithic integrated framework. While maintaining the advantages of semiconductor integrated devices such as small size, compact structure, and simple manufacturing process, it overcomes the problems of severe thermal crosstalk and excessive power consumption caused by the high thermal conductivity of the substrate in traditional monolithic integrated structures, thus achieving a balance between high integration and high thermal tuning efficiency.

[0031] Secondly, the technical solution in this invention avoids optical path alignment errors and packaging complexity caused by discrete chip mounting by performing monolithic integration on the same substrate, thereby improving the overall consistency and repeatability of the array. The technical solution in this invention can suppress current diffusion and lateral light propagation, reduce electrical crosstalk and optical crosstalk, and achieve independent driving and precise tuning of each functional area by introducing functional area electrical isolation trenches and region selective removal of epitaxial layers in the monolithic integrated structure. Attached Figure Description

[0032] The advantages of the above and additional aspects of the present invention will become apparent and readily understood in the description of the embodiments in conjunction with the following drawings, wherein:

[0033] Figure 1 This is a schematic diagram of the structure of an array laser unit according to an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of a unit laser region after an active material has been grown on a substrate according to an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the gain layer of an array laser unit according to an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of a unit laser region after a passive material has been grown on a substrate according to an embodiment of the present invention.

[0037] Figure 5 This is a schematic diagram of the unit laser region after the growth of the capping layer and contact layer according to an embodiment of the present invention;

[0038] Figure 6 This is a schematic diagram of a shallow ridge waveguide structure according to an embodiment of the present invention;

[0039] Figure 7 This is a top view of a cantilever beam structure of an array laser unit according to an embodiment of the present invention;

[0040] Figure 8 This is a side-section schematic diagram of a cantilever beam structure of an array laser unit according to an embodiment of the present invention;

[0041] Figure 9 This is a top view of an array laser unit according to an embodiment of the present invention;

[0042] Figure 10 This is a schematic diagram of the overall structure of an array laser according to an embodiment of the present invention. Detailed Implementation

[0043] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0044] In the following description, many specific details are set forth in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0045] like Figures 1 to 10 As shown, this embodiment provides a method for fabricating an array laser, the method comprising:

[0046] Step 1: Prepare substrate 10. Divide a predetermined number of unit laser regions on substrate 10 according to a preset arrangement direction. In each unit laser region, divide a gain region (labeled 1), a phase region (labeled 2), and a grating region (labeled 3) in sequence. The layout of each unit laser region is the same.

[0047] It should be noted that the number of unit laser regions can be set according to specific needs. In this embodiment, it is set to four, and the four unit laser regions are arranged in the same direction. The division method and arrangement structure of the gain region, phase region and grating region in each unit laser region are consistent. For any unit laser region, the gain region, phase region and grating region are arranged in sequence and the adjacent regions are closely connected.

[0048] Step 2: Active material is grown on substrate 10, and a silicon dioxide thin film 20 is used to cover the gain region in each unit laser region. Then, the active material in other regions outside the gain region is selectively removed to form a gain layer 11 in each unit laser region.

[0049] Specifically, active materials are grown layer by layer from bottom to top on the substrate 10. A silicon dioxide thin film 20 is used to cover the gain region in each unit laser region. Then, the active materials in other regions outside the gain region are removed by dry etching, and the active materials remaining after etching are removed by wet etching with sulfuric acid solution to form a gain layer 11 in each unit laser region. The gain layer 11 includes a lower confinement layer 111, a multiple quantum well layer 112 and an upper confinement layer 113 from bottom to top.

[0050] In this embodiment, the silicon dioxide thin film 20 can be fabricated in the following manner: first, a silicon dioxide thin film with a thickness of 250 nm is grown on the entire substrate 10 using a PECVD (Plasma Enhanced Chemical Vapor Deposition) device; then, a predetermined pattern is formed on the silicon dioxide thin film layer by photolithography and dry etching, such as a mask pattern for the gain region of a quad-array laser, to cover the material layers that do not need to be removed. After the selective removal of other material layers is completed, the patterned silicon dioxide thin film 20 is removed by wet etching or dry etching.

[0051] Step 3: For each unit laser region, passive material is grown in the corresponding region consisting of the phase region and the grating region, the silicon dioxide film 20 is removed, and a uniform grating 121 is formed on top of the passive material within the grating region to form a grating layer 12 in each unit laser region.

[0052] Specifically, for each unit laser region, passive material is grown in the region consisting of the phase region and the grating region using a metal-organic chemical vapor deposition (MOCVD) device. The silicon dioxide film 20 is removed, and a uniform grating 121 is etched above the passive material within the grating region. The uniform grating 121 is a periodically arranged micro-reflective structure (manifested as a row of stripes of equal width, equal spacing, and infinite repetition), ultimately forming a patterned grating layer 12. Then, the silicon dioxide film 20 is used to cover all unit laser regions (including the gain region, phase region, and grating region), and passive material in other regions on the substrate 10 outside of each unit laser region is selectively removed to prevent lateral optical coupling, current diffusion, or parasitic mode propagation between adjacent unit lasers through passive material, thereby reducing optical and electrical crosstalk between array units. Finally, the silicon dioxide film 20 is removed.

[0053] In this embodiment, the uniform grating 121 can be fabricated above the passive material within the grating region by photolithography and dry etching. Specifically, a periodically distributed patterned mask is formed by photolithography, and then the microstructure is etched by reactive ion etching or deep silicon etching. Finally, the patterned mask is removed to complete the fabrication.

[0054] Step 4: A capping layer 13 and a contact layer 14 are grown sequentially from bottom to top above all unit laser regions. For each unit laser region, the capping layer 13 and the contact layer 14 are etched as a whole according to a predetermined ridge pattern to form a shallow ridge waveguide structure. The shallow ridge waveguide structure is laterally distributed in the center of the entire functional layer composed of the gain layer 11, the phase region passive material layer and the grating layer 12.

[0055] Specifically, capping material and contact layer material are grown sequentially from bottom to top over the entire substrate 10. A silicon dioxide thin film 20 is used to cover all unit laser regions (including the gain region, phase region, and grating region). The capping material and contact layer material in other regions of the substrate 10 outside of each unit laser region are selectively removed to prevent the formation of current diffusion channels or lateral light propagation paths between adjacent unit lasers through continuous epitaxial layers, thereby reducing electrical and optical crosstalk between array units. After that, the silicon dioxide thin film 20 is removed.

[0056] For each unit laser region, a transverse strip mask is first fabricated at the center of the contact layer 14. Then, the capping layer 13 and the contact layer 14 in this unit laser region are subjected to SiCl4 gas dry etching to form a shallow ridge structure. The etching depth is controlled within the range of the capping layer 13 and the contact layer 14, and does not penetrate the capping layer 13 to the material layer below it. Then, the two sides of the shallow ridge structure are modified by HCl solution wet etching to finally form an inverted truncated shallow ridge waveguide structure that conforms to the predetermined ridge pattern, and the transverse strip mask is removed.

[0057] For each unit laser region, an electrical isolation trench 141 is etched on the contact layer 14 between the gain region and the phase region, and between the phase region and the grating region, respectively, so that electrical isolation is formed between the gain layer 11, the passive material layer of the phase region and the grating layer 12, to avoid mutual interference of current in each functional region and to ensure that each region is driven and tuned independently.

[0058] It should be noted that when etching the electrical isolation trench 141, a patterned mask corresponding to the electrical isolation trench can be formed first by photolithography, and then the electrical isolation trench 141 can be etched on the electrical contact layer 14 between adjacent areas by dry etching. Finally, the mask is removed to complete the fabrication.

[0059] Step 5: For each unit laser region, the grating layer 12 is etched according to a predetermined cantilever beam pattern to form a cantilever beam structure. The cantilever beam structure includes a cantilever arm 122 located directly below the shallow ridge waveguide structure and air slots 123 symmetrically distributed on both sides.

[0060] Specifically, firstly, two strip regions corresponding to air slots 123 are divided on the upper surface of the grating layer 12 corresponding to each unit laser region. The two strip regions are symmetrically distributed on both sides near the shallow ridge waveguide structure and arranged parallel to the shallow ridge waveguide structure. Then, a mask with a cantilever strip pattern is fabricated on the entire substrate 10 using photolithography. This mask covers all areas on the entire substrate 10 except for the areas where all air slots 123 are located. All passive materials except those corresponding to the air slots 123 are etched away using reactive ion etching equipment and hydrobromic acid. The etching depth is controlled within the grating layer 12 and does not penetrate the grating layer 12 to the substrate 10 below it, so as to form a cantilever beam structure consisting of a central cantilever arm 122 and two symmetrical air slots 123 on both sides in each unit laser region. The width of the upper surface of the cantilever arm 122 is greater than the width of the lower surface of the shallow ridge waveguide structure.

[0061] In this embodiment, preferably, the upper surface of the cantilever arm 122 is 5 micrometers wider than the lower surface of the shallow ridge waveguide structure, and the air slot 123 is an inner hexagonal slot structure, such as... Figure 8 The diagram shown is a side section of the cantilever beam structure. The cantilever arm 122 is an integral structure that is wide at both ends and narrow in the middle.

[0062] Step 6: Fabricate P-side electrodes 15 above the contact layers 14 corresponding to the gain region and phase region, respectively; fabricate heating electrodes 16 above the contact layers 14 corresponding to the grating region; and fabricate N-side electrodes 17 below the substrate 10.

[0063] Specifically, a silicon nitride thin film 18 with a thickness of 250 nm is grown above each unit laser region. Then, P-plane electrodes 15 are fabricated above the contact layers 14 corresponding to the gain region and phase region, respectively. A heating electrode 16 is fabricated above the contact layer 14 corresponding to the grating region using titanium-platinum material. The middle part of the heating electrode 16 is located above the shallow ridge waveguide structure corresponding to the grating region. The two ends of the heating electrode 16 are positive electrodes 161 and negative electrodes 162, which are used to connect to the positive and negative terminals of the external power supply, respectively. Finally, the substrate 10 is thinned and an N-plane electrode 17 is fabricated on the entire surface to provide a common current loop for the entire device.

[0064] It should be noted that the titanium-platinum heating resistor and the silicon nitride insulating film have a strong bonding force. The combination of the two can improve the heating efficiency after energization. Moreover, the silicon nitride insulating film is located below each P-side electrode 15 and the heating electrode 16, which can achieve electrical insulation, surface passivation and structural protection, suppress surface state recombination and metal absorption, and improve device stability and tuning efficiency.

[0065] In this embodiment, under the InP-based material system, the substrate 10 is an N-type InP substrate; the active material used to fabricate the gain layer 11 is InGaAlAs (indium gallium aluminum arsenide), and the passive material used to fabricate the phase region material layer and grating layer 12 is InGaAsP (indium gallium arsenide phosphide); the capping layer 13 is InP material, and the contact layer 14 is InGaAs material; the P-side electrode can be made of titanium gold material, and the N-side electrode can be made of gold germanium nickel alloy material.

[0066] It should be noted that the technical solution of this application achieves integrated multi-array wavelength tunable lasers on a single indium phosphide (InP) substrate through innovative semiconductor microfabrication technology, transforming the thermal tuning of multi-array wavelength tunable lasers into a low-power, high-efficiency process. Specifically, this application fundamentally reduces the difficulty of coupling and aligning multiple light sources by performing monolithic integration on the same substrate. Compared with traditional discrete packaging, integrated fabrication not only significantly reduces the physical size of the device, meeting the miniaturization requirements of optical communication, but also ensures environmental consistency for multiple lasers in key processes such as growth and etching, guaranteeing the balanced overall performance of the array. This application introduces cantilever beam and heat insulation groove structures into each laser, using this structure to solve the problems of high power consumption and severe crosstalk. In traditional chips, the substrate acts as a thermal conductor, causing heat to be rapidly conducted laterally to adjacent laser units. However, this application uses air grooves to quasi-physically isolate each laser in space. Due to the extremely low thermal conductivity of air, this structure can effectively cut off the heat conduction path, ensuring that when one channel is heated and tuned, the heat will not cause temperature fluctuations in neighboring lasers, solving the wavelength drift phenomenon and achieving high precision independent control of each laser unit. With the extremely small thermal capacity of the cantilever beam, only a tiny current is needed to quickly change the local temperature of the grating area, thereby changing the refractive index of the material and achieving rapid wavelength switching. Traditional structures require a lot of extra power consumption to maintain wavelength stability due to the large heat sink effect of the substrate. The cantilever beam design of this application breaks this constraint, so that heat is no longer ineffectively dissipated to the substrate, greatly improving the electrothermal conversion efficiency, enabling the device to be used in low-power, high-density optical network scenarios.

[0067] In this embodiment, the low-power array laser fabricated using the method of this application is tested, specifically including:

[0068] The gain layer 11 was fabricated using InGaAlAs, an active material (lasing wavelength at 1.55 nm). (Band), to fabricate the phase region material layer and grating layer 12, passive material InGaAsP (corresponding to a bandgap wavelength of approximately 1.4 nm) was selected. After the fabrication is completed, one unit laser is randomly selected from the array for testing. Specifically, an 80mA DC current is applied to the gain region, and the gain layer 11 generates stimulated emission, causing the device to emit light and output a laser signal. A 0-50mA driving current is applied to the heating electrode 16 (gradually changing from 0 to 50mA) to locally heat the grating region, achieving mode selection and thermal tuning of the laser wavelength. A current of 0-20mA is applied to the phase region to assist the grating region in achieving continuous wavelength tuning. The center wavelength of the laser output is measured at each current point, and the tuning range of the wavelength as a function of the current of the heating electrode 16 is recorded, finally obtaining the test results.

[0069] Test results show that the unit laser in this example can achieve a quasi-continuous wavelength tuning range of over 12 nm with only a current of 0-35 mA applied to the heating electrode 16. In contrast, traditional monolithic integrated structures typically require a drive current of 0-80 mA to achieve the same tuning range. Therefore, this invention significantly improves electrothermal conversion efficiency through the physical thermal isolation design of the cantilever beam and air trough, greatly reducing the overall power consumption of the device while maintaining the same tuning capability.

[0070] The steps in this invention can be adjusted, combined, or deleted according to actual needs.

[0071] The units in the device of the present invention can be merged, divided, or reduced according to actual needs.

[0072] In this invention, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "linking" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention according to the specific circumstances.

[0073] The shapes of the components in the accompanying drawings are schematic and may differ from their actual shapes. The drawings are only used to illustrate the principles of the present invention and are not intended to limit the present invention.

[0074] Although the invention has been disclosed in detail with reference to the accompanying drawings, it should be understood that these descriptions are merely exemplary and not intended to limit the application of the invention. The scope of protection of the invention 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 invention.

Claims

1. A method of fabricating an array laser, comprising: The method includes: ​ Step 1: Prepare a substrate (10), divide a predetermined number of unit laser regions on the substrate (10) in a predetermined arrangement direction, and divide a gain region, a phase region and a grating region in each unit laser region in a predetermined manner. Step 2: Active material is grown on substrate (10), and a silicon dioxide thin film (20) is used to cover the gain region in each unit laser region. Then, the active material in other regions outside the gain region is selectively removed to form a gain layer (11) in each unit laser region. Step 3: For each unit laser region, passive material is grown in the corresponding region consisting of the phase region and the grating region, the silicon dioxide film (20) is removed, and a uniform grating (121) is made above the passive material within the grating region to form a grating layer (12) in each unit laser region. All unit laser regions are covered with a silicon dioxide film (20), passive materials in other regions outside the unit laser regions on the substrate (10) are selectively removed, and finally the silicon dioxide film (20) is removed. Step 4: A capping layer (13) and a contact layer (14) are grown sequentially from bottom to top above all unit laser regions. For each unit laser region, the capping layer (13) and the contact layer (14) are etched as a whole according to a predetermined ridge pattern to form a shallow ridge waveguide structure. The shallow ridge waveguide structure is laterally distributed in the center of the entire functional layer composed of the gain layer (11), the phase region passive material layer and the grating layer (12). A capping layer material and a contact layer material are grown sequentially from bottom to top over the entire substrate (10). A silicon dioxide film (20) is used to cover all unit laser regions. The capping layer material and contact layer material in other regions outside the individual unit laser regions on the substrate (10) are selectively removed, and then the silicon dioxide film (20) is removed. Step 5: For each unit laser region, the grating layer (12) is etched according to the predetermined cantilever beam pattern to form a cantilever beam structure, which includes a cantilever arm (122) located directly below the shallow ridge waveguide structure and air slots (123) symmetrically distributed on both sides. Step 6: A P-side electrode (15) is fabricated above the contact layer (14) corresponding to the gain region and the phase region, a heating electrode (16) is fabricated above the contact layer (14) corresponding to the grating region, and an N-side electrode (17) is fabricated below the substrate (10).

2. The method of claim 1, wherein the array laser is prepared by the steps of: The layout of each unit laser region is the same. For any unit laser region, the gain region, phase region and grating region are arranged in sequence and adjacent regions are closely connected.

3. The method for fabricating an array laser as described in claim 2, characterized in that, Step 2 specifically includes: Active materials are grown layer by layer from bottom to top on the substrate (10). A silicon dioxide thin film (20) is used to cover the gain region in each unit laser region. Then, active materials in other regions outside all gain regions are removed by dry etching, and the active materials remaining after etching are removed by wet etching with sulfuric acid solution to form a gain layer (11) in each unit laser region. The gain layer (11) includes a lower confinement layer (111), a multi-quantum well layer (112), and an upper confinement layer (113) from bottom to top.

4. The method for fabricating an array laser as described in claim 3, characterized in that, Step 4 also includes: For each unit laser region, a transverse strip mask is first fabricated at the center of the contact layer (14). Then, the capping layer (13) and the contact layer (14) in this unit laser region are subjected to SiCl4 gas dry etching to form a shallow ridge structure. The etching depth is controlled within the range of the capping layer (13) and the contact layer (14), and does not penetrate the capping layer (13) to the material layer below it. Then, the two sides of the shallow ridge structure are modified by HCl solution wet etching to finally form an inverted shallow ridge waveguide structure that conforms to the predetermined ridge pattern, and the transverse strip mask is removed.

5. The method for fabricating an array laser as described in claim 4, characterized in that, Following step 4, the following steps are also included: For each unit laser region, an electrical isolation trench (141) is etched on the contact layer (14) between the gain region and the phase region, and between the phase region and the grating region, respectively, so that electrical isolation is formed between the gain layer (11), the passive material layer of the phase region and the grating layer (12).

6. The method for fabricating an array laser as described in claim 4, characterized in that, Step 5 specifically includes: First, two strip regions corresponding to air slots (123) are divided on the upper surface of the grating layer (12) corresponding to each unit laser region. The two strip regions are symmetrically distributed on both sides of the shallow ridge waveguide structure and are arranged parallel to the shallow ridge waveguide structure. Then, a mask with a cantilever strip pattern is made on the entire substrate (10) using photolithography. The mask is used to cover the entire substrate (10) except for the areas where all air slots (123) are located. All passive materials except for the areas corresponding to air slots (123) are removed by reactive ion etching equipment and hydrobromic acid etching. The etching depth is controlled within the grating layer (12) and does not penetrate the grating layer (12) to the substrate (10) below it, so as to form a cantilever beam structure composed of a central cantilever arm (122) and symmetrical air slots (123) on both sides in each unit laser region. The width of the upper surface of the cantilever arm (122) is greater than the width of the lower surface of the shallow ridge waveguide structure.

7. The method for fabricating an array laser as described in claim 1, characterized in that, Step 6 specifically includes: A silicon nitride thin film is grown above each unit laser region. Then, P-plane electrodes (15) are fabricated above the contact layers (14) corresponding to the gain region and phase region, respectively. A heating electrode (16) is fabricated above the contact layer (14) corresponding to the grating region using titanium-platinum material. The middle part of the heating electrode (16) is located above the shallow ridge waveguide structure corresponding to the grating region. The two ends of the heating electrode (16) are positive electrodes (161) and negative electrodes (162). Finally, the substrate (10) is thinned and N-plane electrodes (17) are fabricated on the entire surface.

Images