A method for fabricating and structure of a tunable laser

Abstract

This invention discloses a method and structure for fabricating a tunable laser. The method includes: laying out a substrate surface to sequentially divide a front gain region, a front phase region, a common grating region, a rear phase region, and a rear gain region; growing an active layer; fabricating a mating mask pattern in the gain region; etching away the active layers in the common grating region and phase region and mating to grow a passive layer; removing the mask and fabricating a grating in the common grating region; growing a cladding layer and an electrical contact layer; fabricating a frustum shallow ridge waveguide structure and etching an electrical isolation trench; forming a cantilever structure in the common grating region and fabricating a titanium-platinum heating resistor, a grating electrode, and a ground electrode; and obtaining a tunable laser after completing the fabrication of the P-side and N-side electrodes. This invention achieves synchronous control of dual-end light output and wavelength by sharing a thermally tunable grating between back-to-back dual lasers. By fabricating the cantilever structure of the grating ridge waveguide, the energy consumption of wavelength tuning is reduced, providing a solution for the future large-scale use of tunable optical emission chips.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic tunable laser technology, and in particular to a method for fabricating and structure of a tunable laser. Background Technology

[0002] With the rapid development of 5G networks, data centers, and artificial intelligence, on the one hand, higher requirements are placed on the bandwidth of data transmission. To improve the bandwidth of a single optical transmitter chip, monolithic integration of multifunctional devices is adopted to make full use of the advantages of each functional device. On the other hand, with the large-scale use of optical transmitter chips, modules, and equipment, reducing the power consumption of each link in optical transmission is becoming increasingly important. As the core chip of optical transmission, the optical transmitter chip is becoming more and more integrated, and solving the power consumption problem of the optical transmitter chip is becoming particularly important.

[0003] Most existing tunable lasers employ independent gain and grating region designs, making it impossible to achieve synchronous output at both ends and high-precision wavelength control. Furthermore, traditional thermally tunable structures suffer from high power consumption, limiting their application in large-scale integration and long-term operation scenarios. In addition, existing fabrication processes suffer from insufficient precision and poor repeatability in selective growth and material etching, leading to unstable device performance and hindering large-scale mass production.

[0004] This invention proposes a method and structure for fabricating a tunable laser. By integrating two wavelength-tunable lasers back-to-back, sharing a grating region, and enabling dual-end beam emission, it achieves synchronous dual-end output and precise wavelength control, significantly improving performance. By fabricating a cantilever structure for the grating ridge waveguide, an air-slot thermal insulation structure is formed, thereby changing wavelength tuning from electrical tuning to thermal tuning. This reduces the energy consumption of wavelength tuning to one-third of the original. Combined with dual-end beam emission, it can greatly reduce the chip's power consumption. This invention provides a new solution for the large-scale application of tunable optical emission chips in the future. Summary of the Invention

[0005] In view of this, the present invention provides a method and structure for fabricating a tunable laser, which can solve the technical problems of difficult wavelength synchronization control, high power consumption and poor heat dissipation in existing tunable lasers.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for fabricating a tunable laser, comprising:

[0008] The substrate is laid out by dividing the substrate surface into a front gain region, a front phase region, a common grating region, a back phase region, and a back gain region along the length direction; an active layer is grown on the substrate surface using a metal-organic chemical vapor deposition device.

[0009] A silicon dioxide layer was grown on the substrate surface using plasma chemical vapor deposition equipment, and docking mask patterns were fabricated in the front and back gain regions using photolithography and wet etching techniques.

[0010] The active layer of the common grating region, the front phase region and the back phase region is removed by etching using reactive ion etching equipment. The substrate is then cleaned and the residual active layer material on the surface is removed by etching.

[0011] A passive layer is grown by means of a metal-organic chemical vapor deposition apparatus in a common grating region, a front phase region and a back phase region; the photofluorescence wavelength of the passive layer is smaller than the photofluorescence wavelength of the front and back gain regions.

[0012] Remove the docking mask pattern, fabricate a grating in the common grating region, and sequentially grow a cladding layer and an electrical contact layer on the overall surface of the laser.

[0013] Fabricate a shallow ridge waveguide structure on the cladding and electrical contact layers;

[0014] Electrical isolation trenches are etched on the electrical contact layer to achieve electrical isolation between functional areas;

[0015] By using reactive ion etching equipment and hydrobromic acid etching on both sides of the ridge waveguide structure in the shared grating area, a cantilever structure is formed in the ridge waveguide structure in the shared grating area.

[0016] A silicon nitride thin film is grown on the surface of the laser to fabricate a titanium-platinum heating resistor for a shared grating region ridge waveguide, as well as grating electrodes and grounding electrodes.

[0017] P-side electrodes are fabricated on the electrode contact layers in the front / back phase region and the front / back gain region. After the substrate is thinned, N-side electrodes are fabricated on the bottom to complete the fabrication of the tunable laser.

[0018] Furthermore, the photofluorescence wavelength of the passive layer is 90-200 nm smaller than that of the photofluorescence wavelength of the gain region.

[0019] Furthermore, the cantilever structure is formed on both sides of the ridge waveguide structure in the shared grating region using reactive ion etching and hydrobromic acid etching, including:

[0020] Within the pre-defined rectangular strip area on both sides of the ridge waveguide structure in the shared grating region, the electrical contact layer, cladding layer, and passive layer are removed by etching using reactive ion etching equipment.

[0021] Hydrobromic acid is used for etching to form a cantilever structure in the ridge waveguide of the shared grating area.

[0022] Furthermore, the cantilever structure includes: hexagonal air slots on both sides of the cantilever, and a cantilever arm below the ridge waveguide.

[0023] Furthermore, the preset rectangular strip area consists of two rectangular slots with a width of 5 micrometers and a length of 350 micrometers, with a slot spacing of 25 micrometers.

[0024] Furthermore, the active layer comprises, from bottom to top, a lower waveguide layer, a multi-quantum well layer, and an upper waveguide layer. The thickness of the lower waveguide layer and the upper waveguide layer is 100 nm. The multi-quantum well layer is formed by alternating growth of multiple quantum well layers and barrier layers.

[0025] Furthermore, both the active layer and the passive layer are made of InGaAsP.

[0026] Furthermore, the step of cleaning the substrate and etching away the active layer material remaining after etching includes: thoroughly cleaning with acetone and ethanol, and etching away the active layer material remaining after etching with H2SiO4 solution.

[0027] Furthermore, the lengths of the front gain region and the rear gain region are both 300 micrometers, the lengths of the front phase region and the rear phase region are both 100 micrometers, and the length of the common grating region is 350 micrometers.

[0028] On the other hand, the present invention also provides a structure of a tunable laser, wherein the structure of the tunable laser is prepared by the preparation method described in the above technical solution, and the laser is divided into a front gain region, a front phase region, a common grating region, a rear phase region and a rear gain region in sequence along the length direction from one side.

[0029] Among them, the photofluorescence wavelengths of the shared grating region, front phase region, and back phase region are 90-200 nm smaller than the photofluorescence wavelengths of the front and back gain regions; the ridge waveguide structure of the shared grating region is a cantilever structure, with hexagonal air slots on both sides of the cantilever, forming an air slot heat insulation structure, which changes the wavelength tuning from electrical tuning to thermal tuning.

[0030] Compared with existing technologies, the advantages of the tunable laser fabrication method and structure provided by this invention are as follows:

[0031] (1) This method integrates two wavelength-tunable lasers back-to-back by sharing a grating structure, enabling dual-end-face light output. This meets the needs of different transmission directions and links, improving the system's flexibility and reliability. In applications requiring precise wavelength matching, such as optical multiplexing and optical sensing, this synchronous control can effectively reduce interference caused by wavelength drift, improving system performance and accuracy. Furthermore, from a production perspective, reducing the number of gratings and their technical complexity can improve production efficiency and reduce the cost per device in large-scale production.

[0032] (2) By fabricating a cantilever structure for the grating ridge waveguide, an air-slot thermal insulation structure is formed, thereby changing the wavelength tuning from electrical tuning to thermal tuning. The energy consumption of wavelength tuning is reduced to one-third of the original. Combined with dual-end light output, the power consumption of the chip is greatly reduced, providing a new solution for the large-scale use of tunable optical emission chips in the future. Lower power consumption can also slow down the aging rate of materials inside the device, extend the lifespan of the laser, and reduce the frequency of device replacement and maintenance costs.

[0033] In summary, this invention solves the problems of wavelength synchronization difficulties, high power consumption, and poor heat dissipation in existing tunable lasers through an innovative shared grating structure and cantilever thermal insulation design. It achieves dual-end light output and low-energy thermal tuning, significantly improving the performance and reliability of optical communication and optical sensing systems, reducing production costs, extending device lifespan, and providing an efficient solution for large-scale applications. Attached Figure Description

[0034] Figure 1 A schematic flowchart illustrating the fabrication method of the tunable laser provided by the present invention;

[0035] Figure 2 This is a schematic diagram of the substrate, region division, and active layer fabrication provided by the present invention.

[0036] Figure 3 A schematic diagram of the structure after etching away the active layer material in the phase region and grating region, as provided in this invention;

[0037] Figure 4 A schematic diagram of the structure after the passive materials in the grating region and phase region are grown by docking, as provided by the present invention;

[0038] Figure 5 A schematic diagram of the structure after fabrication of the grating and growth of the cladding and electrical contact layer provided by the present invention;

[0039] Figure 6 A cross-sectional schematic diagram of a shallow ridge waveguide structure fabricated on the cladding and electrical contact layers provided by the present invention;

[0040] Figure 7 A schematic diagram of the structure after the isolation trenches between the various functional areas are fabricated, as provided by the present invention;

[0041] Figure 8 A schematic diagram of the structure for fabricating air insulation grooves on both sides of the ridge waveguide in the grating region provided by the present invention;

[0042] Figure 9 A cross-sectional schematic diagram of the cantilever beam for fabricating the grating region provided by the present invention;

[0043] Figure 10 This is a schematic diagram showing the distribution of electrodes in various regions on the surface of the device provided by the present invention;

[0044] In the figure, 1-front gain region, 2-front phase region, 3-common grating region, 4-back gain region, 5-back phase region, 10-substrate, 11-lower confinement layer, 12-multiple quantum well layer, 13-upper confinement layer, 14-docking mask pattern, 15-passive layer, 16-grating, 17-cladding, 18-electrical contact layer, 19-rectangular groove, 20-air groove, 21-cantilever arm, 22-grating electrode, 23-ground electrode, 24-first P-plane electrode, 25-second P-plane electrode, 26-third P-plane electrode, 27-fourth P-plane electrode. Detailed Implementation

[0045] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0046] Example 1

[0047] Please see Figure 1 , Figure 1 This embodiment illustrates a flowchart of a method for fabricating a tunable laser, which includes:

[0048] Step S101: Perform surface layout on the substrate, dividing the substrate surface along the length direction into a front gain region, a front phase region, a common grating region, a back phase region, and a back gain region; grow an active layer on the substrate surface using a metal-organic chemical vapor deposition device;

[0049] Step S102: A silicon dioxide layer is grown on the substrate surface using a plasma chemical vapor deposition device, and a docking mask pattern is fabricated in the front / back gain region using photolithography and wet etching techniques.

[0050] Step S103: Use reactive ion etching equipment to etch away the active layer of the common grating region, the front phase region and the back phase region, clean the substrate and etch away the residual active layer material on the surface.

[0051] Step S104: A passive layer is grown by docking the common grating region, the front phase region, and the back phase region using a metal-organic chemical vapor deposition apparatus; the photofluorescence wavelength of the passive layer is smaller than that of the gain region.

[0052] Step S105: Remove the docking mask pattern, fabricate a grating in the common grating area, and sequentially grow a cladding layer and an electrical contact layer on the overall surface of the device;

[0053] Step S106: Fabricate a shallow ridge waveguide structure on the cladding and electrical contact layer;

[0054] Step S107: Etch electrical isolation trenches on the electrical contact layer to achieve electrical isolation between functional areas;

[0055] Step S108: Using reactive ion etching equipment and hydrobromic acid etching on both sides of the ridge waveguide structure in the common grating region, a cantilever structure is formed in the ridge waveguide structure in the common grating region.

[0056] Step S109: Grow a silicon nitride thin film on the surface of the laser, fabricate a titanium-platinum heating resistor for the common grating region ridge waveguide, as well as grating electrodes and ground electrodes;

[0057] Step S110: Fabricate P-side electrodes on the electrode contact layers of the front phase region, back phase region, and gain region. After thinning the substrate, fabricate N-side electrodes on the bottom to complete the fabrication of the tunable laser.

[0058] The tunable laser fabrication method provided in this embodiment integrates two wavelength tunable lasers back-to-back. By fabricating a cantilever structure of a grating ridge waveguide, an air slot heat insulation structure is formed, thereby changing wavelength tuning from electrical tuning to thermal tuning. The energy consumption of wavelength tuning is reduced to one-third of the original. Combined with dual-end light output, the power consumption of the chip is greatly reduced, providing a new solution for the large-scale use of tunable optical emission chips in the future.

[0059] The following is combined with Figures 2-10 The above steps will be demonstrated and explained in detail.

[0060] As a specific embodiment, the steps of this manufacturing method include:

[0061] (1) Select an N-type indium phosphide substrate 10 and divide the substrate surface along the length direction into a front gain region 1, a front phase region 2, a common grating region 3, a back phase region 4 and a back gain region 5; wherein, the length of the front gain region is 300 micrometers, the length of the front phase region 2 is 100 micrometers, the length of the common grating region 3 is 350 micrometers, the length of the back phase region 4 is 100 micrometers, and the length of the back gain region 5 is 300 micrometers.

[0062] (2) An active layer is grown on the substrate using a metal-organic chemical vapor deposition (MOCVD) apparatus. The active layer is made of InGaAsP and includes a lower confinement layer 11, a multiple quantum well layer 12, and an upper confinement layer 13. The lower confinement layer 11 and the upper confinement layer 13 are both 100 nm thick. The multiple quantum well layer 12 is formed by alternating growth of six 5 nm thick quantum well layers and seven 9 nm thick barrier layers, such as... Figure 2 As shown.

[0063] (3) A SiO2 layer with a thickness of 200 nm is grown on the substrate surface using plasma chemical vapor deposition equipment, and a docking mask pattern 14 is fabricated in the gain region 4 using photolithography and wet etching techniques.

[0064] (4) The InGaAsP active layer material of the common grating region 3, the front phase region 2 and the back phase region 4 is removed by etching using a reactive ion etching device. The substrate is cleaned with acetone and ethanol, and the residual InGaAsP material is removed by etching with H2SiO4 solution. At this time, the structure of the laser is as follows: Figure 3 As shown.

[0065] (5) A passive layer sharing the grating region 3, the front phase region 2, and the back phase region 4 is grown using a metal-organic chemical vapor deposition (MOCVD) apparatus. The passive layer is InGaAsP bulk material 15, and its photofluorescence wavelength is 90-200 nm shorter than that of the gain region. Figure 4 As shown. It should be noted that the photofluorescence wavelengths of the grating region and phase region are designed to be shorter than those of the front and rear gain regions. This allows for a blue shift of the grating region and phase region relative to the gain region. During laser operation, the gain region provides efficient optical amplification, while the phase region precisely controls the phase of the light wave, thereby ensuring the output spectral quality and tuning accuracy of the laser.

[0066] (6) Remove the docking mask pattern 14, fabricate a grating 16 in the common grating region 3, and then grow a cladding layer 17 and an electrical contact layer 18 on the surface using a metal-organic chemical vapor deposition (MOCVD) apparatus. The cladding layer 17 is a 1.5 μm thick InP layer; the electrical contact layer 18 is a 300 nm thick InGaAs layer, with the specific structure as follows: Figure 5 As shown.

[0067] (7) Fabricate a shallow ridge waveguide structure on the entire cladding 17 and electrical contact layer 18 of the material, such as Figure 6 As shown, Figure 6 A cross-sectional view of the shallow ridge waveguide is shown;

[0068] (8) An electrical isolation trench is etched on the ridge wave conductive contact layer 18. The width of the electrical isolation trench is 50 micrometers, thereby achieving electrical isolation between the shared grating region 3, the front phase region 2 and the back phase region 4, and the front gain region 1 and the back gain region 5. The structure at this time is as follows: Figure 7 As shown.

[0069] (9) Within the rectangular strip regions 19 on both sides of the ridge waveguide of the common grating region 3, 400 nm of semiconductor material is etched away using reactive ion etching equipment, followed by hydrobromic acid etching for 20 minutes to form a cantilever structure in the ridge waveguide of the common grating region 3. Two rectangular grooves, each 5 micrometers wide and 350 micrometers long, are set in the rectangular groove region, with a spacing of 25 micrometers. Figure 8 As shown, Figure 8 This is a top view of the layout of rectangular bar area 19. (Example) Figure 9As shown, the cantilever arms of the ridge waveguide in the shared grating region 3 are hexagonal air slots 20 on both sides, and the cantilever arm 21 is below the ridge waveguide.

[0070] Specifically, the working principle and effects of the above setup are introduced here. By hollowing out the sides and facets of the ridge waveguide in the grating region, physical isolation is achieved between it and the semiconductor material. The space between the structures is filled with air, which has poor thermal conductivity, preventing heat dissipation from the grating region. This allows for easy alteration of the temperature of the ridge waveguide, thereby changing the refractive index of the grating material and ultimately altering the grating period. Changing the grating period alters the laser's lasing wavelength, thus achieving wavelength tuning, changing wavelength tuning from electrical tuning to thermal tuning. Thermal tuning significantly reduces power consumption compared to traditional electrical tuning. This is because electrical tuning requires high current to change the refractive index, while thermal tuning only requires low-power heating resistors, thus reducing energy loss, extending device lifespan, and lowering operating costs, making it particularly suitable for large-scale photonic integration applications. Furthermore, this structure optimizes the heat dissipation characteristics of the grating region. The hollowed-out design allows heat to dissipate easily to the surrounding environment, preventing overheating that could lead to performance degradation or damage, and improving the laser's operational stability and reliability.

[0071] (10) A silicon nitride thin film with a thickness of 250 nm is grown on the surface of the laser using plasma vapor deposition equipment to fabricate a titanium-platinum heating resistor with a shared grating region 3-ridge waveguide. The titanium-platinum heating resistor has a strong bonding force with the silicon nitride substrate and has a high temperature coefficient of resistance, resulting in high heating efficiency after being powered on.

[0072] Simultaneously, grating electrodes 22 and ground electrodes 23 are fabricated; first P-plane electrodes 24 and second P-plane electrodes 25 are fabricated in the front phase region 2 and the rear phase region 4, respectively; third P-plane electrodes 26 and fourth P-plane electrodes 27 are fabricated in the front gain region 1 and the rear gain region 5, respectively; after substrate thinning, N-plane electrodes are fabricated at the bottom of the entire device, completing the fabrication of the laser. Figure 10 As shown, Figure 10 This is a top view of the completed laser.

[0073] The tunable laser fabrication method provided in this embodiment integrates two wavelength tunable lasers back-to-back. By fabricating a cantilever structure of a grating ridge waveguide, an air slot heat insulation structure is formed, thereby changing wavelength tuning from electrical tuning to thermal tuning. The energy consumption of wavelength tuning is reduced to one-third of the original. Combined with dual-end light output, the power consumption of the chip is greatly reduced, providing a new solution for the large-scale use of tunable optical emission chips in the future.

[0074] Example 2

[0075] This invention also provides a laser structure, which is fabricated using the tunable laser fabrication method described in Embodiment 1. The laser is fabricated using the method described in the above technical solution, and the laser, starting from one side, is as follows: Figure 7 As shown, along the length direction, it is divided into front gain region 1, front phase region 2, common grating region 3, rear phase region 4 and rear gain region 5;

[0076] Among them, the photofluorescence wavelength of the shared grating region 3, the front phase region 2 and the back phase region 4 is 90-200nm smaller than that of the gain region; the ridge waveguide structure of the shared grating region 3 is a cantilever structure, and the two sides of the cantilever are hexagonal air slots, forming an air slot heat insulation structure, so that the wavelength tuning is changed from electrical tuning to thermal tuning.

[0077] The laser structure provided in this embodiment achieves dual-end light output through the layout of the front gain region, front phase region, common grating region, rear phase region, and rear gain region, meeting the requirements of different transmission directions and links, and improving system flexibility and reliability. In applications such as optical multiplexing and optical sensing, it effectively reduces wavelength drift interference, improving system performance and accuracy. The cantilever structure of the common grating region and the air slot thermal insulation structure formed by the hexagonal air slot change wavelength tuning from electrical tuning to thermal tuning, reducing power consumption by two-thirds and significantly reducing chip power consumption, providing a new solution for the large-scale use of tunable optical emission chips. At the same time, low power consumption slows down the aging of internal materials, extends the laser's lifespan, and reduces replacement frequency and maintenance costs. The photofluorescence wavelengths of the common grating region, front phase region, and rear phase region are 90-200 nm smaller than those of the gain region, which helps optimize the laser's optical performance and improve tuning efficiency and stability.

[0078] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for fabricating a tunable laser, characterized in that, include: The substrate is laid out by dividing the substrate surface along the length direction into the front gain region, the front phase region, the common grating region, the back phase region, and the back gain region. An active layer is grown on the substrate surface using a metal-organic chemical vapor deposition (MOCVD) apparatus. A silicon dioxide layer was grown on the substrate surface using plasma chemical vapor deposition equipment, and docking mask patterns were fabricated in the front and back gain regions using photolithography and wet etching techniques. The active layer of the common grating region, the front phase region and the back phase region is removed by etching using reactive ion etching equipment. The substrate is then cleaned and the residual active layer material on the surface is removed by etching. A passive layer is grown by means of a metal-organic chemical vapor deposition apparatus in a common grating region, a front phase region and a back phase region; the photofluorescence wavelength of the passive layer is smaller than the photofluorescence wavelength of the front and back gain regions. Remove the docking mask pattern, fabricate a grating in the common grating region, and sequentially grow a cladding layer and an electrical contact layer on the overall surface of the laser. Fabricate a shallow ridge waveguide structure on the cladding and electrical contact layers; Electrical isolation trenches are etched on the electrical contact layer to achieve electrical isolation between functional areas; A cantilever structure is formed on both sides of the ridge waveguide structure in the shared grating region using reactive ion etching and hydrobromic acid etching; including: Within the pre-defined rectangular strip area on both sides of the ridge waveguide structure in the shared grating region, the electrical contact layer, cladding layer, and passive layer are removed by etching using reactive ion etching equipment. Hydrobromic acid is used for etching to form a cantilever structure in the ridge waveguide of the shared grating region; the cantilever structure includes: hexagonal air slots on both sides of the cantilever and a cantilever arm below the ridge waveguide. A silicon nitride thin film is grown on the surface of the laser to fabricate a titanium-platinum heating resistor for a shared grating region ridge waveguide, as well as grating electrodes and grounding electrodes. P-side electrodes are fabricated on the electrode contact layers in the front / back phase region and the front / back gain region. After the substrate is thinned, N-side electrodes are fabricated on the bottom to complete the fabrication of the tunable laser.

2. The method for fabricating a tunable laser according to claim 1, characterized in that, The photofluorescence wavelength of the passive layer is 90-200 nm smaller than that of the gain region.

3. The method for fabricating a tunable laser according to claim 1, characterized in that, The preset rectangular strip area consists of two rectangular slots with a width of 5 micrometers and a length of 350 micrometers, with a slot spacing of 25 micrometers.

4. The method for fabricating a tunable laser according to claim 1, characterized in that, The active layer comprises, from bottom to top, a lower waveguide layer, a multi-quantum well layer, and an upper waveguide layer. The thickness of the lower waveguide layer and the upper waveguide layer is 100 nm. The multi-quantum well layer is formed by alternating growth of multiple quantum well layers and barrier layers.

5. The method for fabricating a tunable laser according to claim 1, characterized in that, Both the active and passive layers are made of InGaAsP.

6. The method for fabricating a tunable laser according to claim 1, characterized in that, The process of cleaning the substrate and etching away residual active layer material includes: thoroughly cleaning with acetone and ethanol, and etching away residual active layer material and defects from the etching process with H2SiO4 solution.

7. The method for fabricating a tunable laser according to claim 1, characterized in that, The lengths of the front gain region and the back gain region are both 300 micrometers, the lengths of the front phase region and the back phase region are both 100 micrometers, and the length of the common grating region is 350 micrometers.

8. A structure for a tunable laser, characterized in that, The structure of the tunable laser is prepared by the fabrication method described in any one of claims 1-7 above. The laser is divided into a front gain region, a front phase region, a common grating region, a rear phase region and a rear gain region in sequence along the length direction, starting from one side. Among them, the photofluorescence wavelengths of the shared grating region, front phase region, and back phase region are 90-200 nm smaller than the photofluorescence wavelengths of the front and back gain regions; the ridge waveguide structure of the shared grating region is a cantilever structure, with hexagonal air slots on both sides of the cantilever, forming an air slot heat insulation structure, which changes the wavelength tuning from electrical tuning to thermal tuning.

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