A preparation method of a transmitting chip covering C-band and L-band light

Abstract

This invention discloses a method for fabricating an emitting chip covering C-band and L-band light, belonging to the field of semiconductor optoelectronic integrated device technology. The method divides a substrate into a combiner region, a waveguide region, and two laser regions. The laser region includes an amplifier region, front and rear grating regions, and a gain region. Active materials are then grown in the amplifier and gain regions, while passive materials are grown in the front and rear gratings, combiner, and waveguide regions. Sampling gratings with different sampling periods are fabricated above the front and rear grating regions in each laser region, so that the operating wavelengths of the two laser units cover the C and L bands respectively. A capping layer and a contact layer are grown, and a shallow ridge waveguide structure and a cantilever beam structure are fabricated in each laser region. Finally, a P-side electrode and a heating electrode are fabricated. This invention deeply integrates the cantilever beam thermally tuned structure, the differentiated sampling grating, and the on-chip combiner, expanding the device tuning width while realizing independent tuning and decoupling control of the two lasers and reducing 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 emitting chip that covers C-band and L-band light. Background Technology

[0002] With the explosive growth of optical communication and artificial intelligence services, the demand for network bandwidth resources is becoming increasingly urgent, and the requirements for the modulation bandwidth of single-wavelength optical emitting devices are constantly increasing. However, due to the physical properties of semiconductor materials themselves, the modulation bandwidth of single-wavelength optical emitting chips cannot be increased indefinitely. Therefore, the industry is turning to the use of wavelength-tunable lasers to utilize more wavelength resources. Traditional methods face multiple technical bottlenecks when attempting to cover the entire C+L wavelength band (1530nm-1630nm): First, the tuning range of a single tunable laser is limited by the gain medium spectral width and grating tuning capability, making it difficult to stably cover a range exceeding 60nm. This makes it impossible to achieve full C+L wavelength coverage with a single laser. Furthermore, due to manufacturing deviations in semiconductor processes, the actual effective tuning range of the laser is often smaller than the theoretical value, and its operational stability is easily affected by environmental interference. Second, when achieving monolithic integration of multiple light sources, traditional fabrication processes struggle to consider the independent thermal performance of each functional unit. As the substrate acts as a thermal conductor, the thermal resistance paths between units cannot be effectively severed after subsequent metal electrode processing and thinning processes. This results in severe electrical interference and thermal crosstalk between lasers, making it impossible to perform decoupled tuning calibration of dual lasers, leading to difficulties in wavelength locking and poor reliability. While using discrete component combination schemes can reduce crosstalk, it introduces cumbersome mechanical coupling and multi-chip alignment processes, resulting in decreased packaging yield and extremely high coupling losses. Furthermore, it cannot achieve chip-level lightweight and low-power manufacturing.

[0003] Therefore, how to achieve a transmitter chip with wide spectral coverage, high thermal isolation, and excellent electro-optic conversion efficiency on a single chip through optimized fabrication process has become a pressing technological challenge in the field of optoelectronic integration. Summary of the Invention

[0004] The purpose of this invention is to provide a method for fabricating an emitting chip that covers both C-band and L-band light, in order to solve the technical problems of limited tuning range of existing single-unit tunable lasers, micro-area thermal field runaway under high-density integration, and excessive size and power consumption and complicated process flow that makes it difficult to integrate discrete devices. Through the collaborative design of a dual-machine parallel architecture with different wavelengths and a cantilever beam micro-nano thermal isolation structure, low power consumption, high precision, and continuous tuning output across the entire C-to-L wavelength band can be achieved on a single chip.

[0005] The technical solution of this invention is: a method for fabricating an emitting chip covering C-band and L-band light, the method comprising:

[0006] Step 1: Prepare the substrate. Divide the substrate into a combiner region, a waveguide region, and two parallel unit laser regions. In each unit laser region, divide it into an amplifier region, a front grating region, a gain region, and a rear grating region. The waveguide region includes two input paths and a single output path. The two input paths are connected to the amplifier regions of the two unit laser regions, and the single output path is connected to the combiner region.

[0007] Step 2: Grow active material on the substrate, cover the amplifier region and gain region in the two unit laser regions with a mask, and selectively remove active material in other regions to form an amplifier layer and a gain layer in each unit laser region.

[0008] Step 3: On the substrate, passive materials are grown in areas other than the amplifier region and the gain region. The mask is removed, and sampling gratings with different sampling periods are fabricated on the passive materials in the front and rear grating regions of each unit laser region to form a patterned front grating layer and a rear grating layer in each unit laser region. The operating wavelength of the first laser unit covers the C-band, and the operating wavelength of the second laser unit covers the L-band.

[0009] Step 4: In the combiner region, waveguide region and two unit laser regions, capping material and contact layer material are grown sequentially from bottom to top. For each unit laser region, the inner capping material and contact layer material are etched as a whole according to the predetermined ridge pattern to form a shallow ridge waveguide structure. The shallow ridge waveguide structure is laterally distributed in the center of the corresponding unit laser region.

[0010] Step 5: For each unit laser region, the passive material in the rear grating region is etched according to the predetermined cantilever beam pattern to form a cantilever beam structure. The cantilever beam structure includes a cantilever beam located directly below the shallow ridge waveguide structure and air slots symmetrically distributed on both sides.

[0011] Step 6: For each unit laser region, fabricate P-surface electrodes on the contact layer material corresponding to the amplifier region, front grating region and gain region, respectively, fabricate heating electrodes on the contact layer material corresponding to the rear grating region, and fabricate N-surface electrodes under the substrate.

[0012] Furthermore, step 2 specifically includes:

[0013] Active materials are grown layer by layer from bottom to top on the substrate. A mask is used to cover the amplifier region and gain region in each unit laser region. Then, active materials in all regions other than the amplifier region and gain region are removed by dry etching. The active materials remaining after etching are removed by wet etching with sulfuric acid solution to form a first amplifier layer and a first gain layer in the first unit laser region, and a second amplifier layer and a second front grating layer in the first unit laser region.

[0014] Furthermore, step 2 also includes: setting a first gain layer in the gain region of the first unit laser region, which includes a first lower confinement layer, a first multiple quantum well layer and a first upper confinement layer from bottom to top; and setting a first amplifier layer in the amplifier region of the first unit laser region, which includes a second lower confinement layer, a second multiple quantum well layer and a second upper confinement layer from bottom to top.

[0015] Furthermore, step 3 specifically includes:

[0016] Passive materials are grown in the front and rear grating regions of two unit laser regions, as well as in the region consisting of a combiner region and a waveguide region, using a metal-organic chemical vapor deposition (MOCVD) apparatus. The mask is removed, and sampling gratings with a first sampling period and a second sampling period are fabricated over the passive materials in the front and rear grating regions of the first unit laser region, respectively, to form a patterned first front grating layer and a first rear grating layer in the first unit laser region. Similarly, sampling gratings with a third sampling period and a fourth sampling period are fabricated over the passive materials in the front and rear grating regions of the second unit laser region, respectively, to form a patterned second front grating layer and a second rear grating layer in the second unit laser region. A mask is used to cover the combiner region, the waveguide region, and all unit laser regions. Passive materials in other regions of the substrate are selectively removed to form a waveguide layer in the waveguide region and a combiner layer in the combiner region.

[0017] Furthermore, in step 3, the values ​​of the first sampling period and the second sampling period are both configured such that the comb reflection spectrum range of the first front grating layer and the first rear grating layer both cover the C-band; the values ​​of the third sampling period and the fourth sampling period are both configured such that the comb reflection spectrum range of the second front grating layer and the second rear grating layer both cover the L-band.

[0018] The photofluorescence wavelength of the passive material is 100 nm shorter than that of the first and second quantum well layers.

[0019] Furthermore, step 4 specifically includes:

[0020] Capping material and contact layer material are grown sequentially from bottom to top over the entire substrate. A mask is used to cover the combiner region, waveguide region and two unit laser regions. Capping material and contact layer material in other regions of the substrate are selectively removed. Then the mask is removed to form a third capping layer and a third contact layer in the waveguide region and a fourth capping layer and a fourth contact layer in the combiner region.

[0021] For each unit laser region, a transverse strip-shaped region is first defined at the center of the upper surface of the contact layer material. A mask is used to cover the wave combiner region, waveguide region, and the transverse strip-shaped region in both unit laser regions. Then, the capping material and contact layer material in each unit laser region are subjected to SiCl4 gas dry etching to form a first shallow ridge structure in the first unit laser region and a second shallow ridge structure in the second unit laser region. The etching depth is controlled within the range of the capping material and contact layer material. Then, HCl solution wet etching is used to modify the two side surfaces of the first and second shallow ridge structures. Finally, the mask is removed.

[0022] Furthermore, step 4 also includes: for the first unit laser region, etching an electrical isolation trench above the first contact layer between its amplifier region and the front grating region, the front grating region and the gain region, and the gain region and the rear grating region, respectively; for the second unit laser region, performing the same etching operation to form a second electrical isolation trench.

[0023] Furthermore, step 4 specifically includes:

[0024] For the first unit laser region, two strip regions corresponding to the air slots are first divided on the upper surface of the first rear grating layer corresponding to the rear grating region. These two strip regions are symmetrically distributed on both sides of the first shallow ridge waveguide structure and arranged parallel to the first shallow ridge waveguide structure. Then, the same two strip regions are divided on the upper surface of the second rear grating layer in the second unit laser region. A mask with a cantilever strip pattern is fabricated above the entire substrate. The mask is used to cover the other areas on the substrate except for all the strip regions. The passive material corresponding to all the strip regions is removed by reactive ion etching equipment and hydrobromic acid etching. The etching depth is controlled within the passive material corresponding to the rear grating region, so as to form a cantilever beam structure in the two unit laser regions, which consists of a central cantilever beam and air slots symmetrically distributed on both sides.

[0025] Furthermore, step 6 specifically includes:

[0026] First, a first P-surface electrode is fabricated above the first contact layer corresponding to the amplifier region, the front grating region, and the gain region within the first unit laser region. Simultaneously, a second P-surface electrode is fabricated above the second contact layer corresponding to the amplifier region, the front grating region, and the gain region within the first unit laser region. Then, a first heating electrode is fabricated above the first contact layer corresponding to the rear grating region within the first unit laser region. Simultaneously, a second heating electrode is fabricated above the second contact layer corresponding to the rear grating region within the second unit laser region.

[0027] The beneficial effects of this invention are:

[0028] First, the technical solution of this invention integrates two sampling grating lasers with different parameters in parallel during the manufacturing process. The two lasers cover the 1530-1575nm and 1575-1630nm wavelength bands, respectively. The output optical signals of the two lasers are output through a waveguide structure and a combiner. This technical solution uses two lasers to expand the tuning width by dividing the spectrum, so that the device can completely cover the entire frequency space from the C-band to the L-band. This design method not only avoids the instability of single-tube lasers at extreme tuning edges, but also ensures that each sub-band is in the optimal operating area of ​​the corresponding laser, which greatly improves the overall reliability of the device and the continuity of wavelength coverage.

[0029] Secondly, the technical solution of this invention integrates lasers covering different wavelength bands on the same chip, and introduces a cantilever beam structure with air insulation grooves and corresponding heating electrodes in the grating area behind each laser. Utilizing the excellent thermal confinement effect of the cantilever beam structure, the heat conduction range is limited to the tiny cantilever beam space, physically isolating the heat conduction path between lasers. This effectively solves the problem of thermal crosstalk in multi-source monolithic integration, realizes completely independent tuning and decoupling control of dual lasers, and significantly improves the flexibility of wavelength switching and the accuracy of frequency locking. The technical solution of this invention adopts a spectrum segmentation and spatial multiplexing strategy, which can achieve spectral purity (i.e., side-mode suppression ratio) far exceeding that of traditional single-tube solutions while ensuring ultra-wide coverage.

[0030] Third, the technical solution of this invention deeply integrates the cantilever beam thermal tuning structure, sampling grating, and on-chip multiplexer, achieving a complete functional chain through the same fabrication process. The extremely small thermal capacity of the cantilever beam endows the device with extremely high thermal efficiency, significantly reducing tuning power consumption and minimizing ineffective heating of the substrate, thus meeting energy-saving requirements. At the same time, the on-chip integration of the passive waveguide and multiplexer eliminates the cumbersome packaging and alignment process of discrete components, greatly reducing chip size. The technical solution of this invention can achieve smooth tuning across bands with extremely low thermal budget without sacrificing the spectral performance of a single tube, resolving the contradiction between wide range and high precision / low power consumption in traditional ultra-wideband lasers, and conforming to the development trend of lightweight and high-efficiency optical emission chips. Attached Figure Description

[0031] 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:

[0032] Figure 1 This is a side-section schematic diagram of the first laser unit prepared using the method of the present invention;

[0033] Figure 2 This is a top view of an emitting chip covering C-band and L-band light, prepared using the method of this invention.

[0034] Figure 3 This is a side-section schematic diagram of the substrate after the active material has been grown using the method of the present invention;

[0035] Figure 4 This is a side-section diagram of a substrate after passive material has been grown using the method of this invention;

[0036] Figure 5 This is a top view of the substrate after the shallow ridge waveguide structure and cantilever beam structure have been fabricated using the method of this invention.

[0037] Figure 6 This is a side-section schematic diagram of a cantilever beam structure fabricated using the method of this invention.

[0038] Among them, 10-first laser unit, 20-second laser unit, 30-combiner, 40-waveguide structure, 50-substrate, 11-first amplifier layer, 111-second lower confinement layer, 112-second multiple quantum well layer, 113-second upper confinement layer, 12-first front grating layer, 13-first gain layer, 131-first lower confinement layer, 132-first multiple quantum well layer, 133-first upper confinement layer, 14-first rear grating layer, 141-cantilever beam, 142-air slot, 142-sampling grating, 15-first capping layer, 16-first Contact layer, 161-first electrical isolation trench, 17-first P-side electrode, 18-first heating electrode, 181-positive electrode, 182-negative electrode, 19-N-side electrode, 21-second amplifier layer, 22-second front grating layer, 23-second gain layer, 24-second rear grating layer, 25-first shallow ridge waveguide structure, 26-second shallow ridge waveguide structure, 27-second P-side electrode, 28-second heating electrode, 31-waveguide layer, 32-third capping layer, 33-third contact layer, 41-combiner layer, 42-fourth capping layer, 43-fourth contact layer. Detailed Implementation

[0039] 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.

[0040] 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.

[0041] like Figures 1 to 6 As shown, this embodiment provides a method for fabricating an emitting chip covering C-band and L-band light, the method comprising:

[0042] Step 1: Prepare substrate 50. Divide substrate 50 into a combiner region, a waveguide region, and two parallel unit laser regions. In each unit laser region, divide it into an amplifier region, a front grating region, a gain region, and a rear grating region. The layout of the two unit laser regions is the same. The waveguide region includes two input paths and a single output path. The two input paths are coupled to the output path. The ends of the two input paths away from the coupling position are connected to the amplifier regions of the two unit laser regions to the right. The two input paths are closely connected to their respective amplifier regions. The single output path is connected to the combiner region and is closely connected to the combiner region.

[0043] It should be noted that the division method within each unit laser region remains consistent. For any given unit laser region, there is an amplifier region (labeled 1), a front grating region (labeled 2), a gain region (labeled 3), and a rear grating region (labeled 4), with these regions arranged sequentially and adjacent regions closely connected. For example... Figure 5 As shown, the waveguide region is Y-shaped; the areas covered by the combiner region (labeled 6), the waveguide region (labeled 5), and the two laser units are distributed sequentially along a preset arrangement direction, and the waveguide region is located between the areas covered by the combiner region and the two laser units.

[0044] In this embodiment, the number of unit laser regions can be set according to specific needs; in this embodiment, it is set to two. In this embodiment, the preset arrangement direction is as follows: Figure 2 The direction shown is from top to bottom, and the default direction is as follows: Figure 2 The direction shown is from left to right. (As shown) Figure 2 The direction from left to right or from right to left is horizontal.

[0045] Step 2: Active material is grown on substrate 50. A silicon dioxide thin film is used to cover the amplifier region and gain region in the two unit laser regions, and active material in other regions is selectively removed to form an amplifier layer and a gain layer in each unit laser region.

[0046] Specifically, active materials are grown layer by layer from bottom to top on the substrate 50. A silicon dioxide thin film is used to cover the amplifier region and gain region in each unit laser region. Then, active materials in all regions other than the amplifier region and gain region are removed by dry etching. The active materials remaining after etching are removed by wet etching with sulfuric acid solution to form a first amplifier layer 11 and a first gain layer 13 in the first unit laser region. A second amplifier layer 21 and a second front grating layer 22 are formed in the first unit laser region.

[0047] The first gain layer 13 is disposed in the gain region of the first unit laser region, and it includes, from bottom to top, a first lower confinement layer 131, a first multiple quantum well layer 132, and a first upper confinement layer 133. The first gain layer 13 is used to provide a light source and gain medium for the first laser unit to emit light. It generates photon gain by injecting current, so that the device emits tunable optical signals. The first multiple quantum well layer 132 is an active layer that provides laser gain. The first lower confinement layer 131 and the first upper confinement layer 133 are used to form the lower and upper potential barriers of the quantum well, respectively, to restrict the movement of charge carriers in the quantum well, prevent their diffusion, and ensure the stability of the optical field and charge carrier distribution.

[0048] The first amplifier layer 11 is disposed in the amplifier region of the first unit laser region. It includes, from bottom to top, a second lower confinement layer 111, a second multiple quantum well layer 112, and a second upper confinement layer 113. The first amplifier layer 11 is used to perform power compensation and amplification on the optical signal output by the first laser unit. It generates stimulated emission by injecting bias current to make the output power of the device reach a preset intensity and improve the signal-to-noise ratio of the system. The second multiple quantum well layer 112 serves as an optical amplification medium. It increases the photon density passing through the region through stimulated emission to achieve optical power gain. The second lower confinement layer 111 and the second upper confinement layer 113 are used to form the lower and upper potential barriers of the quantum well, respectively, to restrict the movement of charge carriers in the quantum well, improve the overlap efficiency of charge carriers and the optical field, and ensure the linearity and stability of the amplification gain.

[0049] It should be noted that the silicon dioxide thin film can be etched. Specifically, a 250nm thick silicon dioxide thin film is first grown on the entire substrate 50 using plasma-enhanced chemical vapor deposition (PECVD). Then, a predetermined pattern is created on the silicon dioxide thin film layer by photolithography and dry etching, such as creating mask patterns for the amplifier area and gain area in each unit laser region to cover the material layers that do not need to be removed. After selective removal of other material layers and docking growth operations are completed, the patterned silicon dioxide thin film is removed by wet etching or dry etching.

[0050] Step 3: On the substrate 50, passive materials are grown in all regions other than the amplifier region and gain region, the silicon dioxide film is removed, and sampling gratings with different sampling periods are fabricated on the passive materials in the front grating region and the back grating region of each unit laser region to form patterned front grating layer and back grating layer in each unit laser region. The operating wavelength of the first laser unit covers the C-band, and the operating wavelength of the second laser unit covers the L-band.

[0051] Specifically, passive materials are grown by mating in the front and rear grating regions of the two unit laser regions, as well as in the region consisting of the combiner region and the waveguide region, using a metal-organic chemical vapor deposition (MOCVD) apparatus. The silicon dioxide film is removed. Then, sampling gratings with a first sampling period and a second sampling period are fabricated on top of the passive materials in the front and rear grating regions of the first unit laser region, respectively, to form a patterned first front grating layer 12 and a first rear grating layer 14 in the first unit laser region. Similarly, sampling gratings with a third sampling period and a second sampling period are fabricated on top of the passive materials in the front and rear grating regions of the second unit laser region. The sampling grating of the fourth sampling period is used to form a patterned second front grating layer 22 and a second rear grating layer 24 in the second unit laser region. The values ​​of the first and second sampling periods are configured such that the comb-shaped reflection spectrum range of the first front grating layer 12 and the first rear grating layer 14 both cover the C-band. The values ​​of the third and fourth sampling periods are configured such that the comb-shaped reflection spectrum range of the second front grating layer 22 and the second rear grating layer 24 both cover the L-band. The photofluorescence wavelength of the passive material is 100 nm shorter than the photofluorescence wavelength of the first quantum well layer 132 and the second quantum well layer 112.

[0052] A silicon dioxide thin film is used to cover the combiner region, waveguide region, and all unit laser regions (including amplifier region, front grating region, gain region, and rear grating region). Passive materials in other regions on the substrate 50 are selectively removed to prevent lateral optical coupling, current diffusion, or parasitic mode propagation between adjacent unit lasers through passive materials, thereby reducing optical and electrical crosstalk between array units. Finally, the silicon dioxide thin film is removed to form a waveguide layer 31 in the waveguide region and a combiner layer 41 in the combiner region.

[0053] In this embodiment, the sampling grating can be fabricated above the passive material within the front and rear grating regions using photolithography and dry etching. That is, a periodically distributed patterned mask is formed by photolithography, and then the microstructure is etched using reactive ion etching or deep silicon etching processes. Finally, the patterned mask is removed.

[0054] It should be noted that the sampling grating consists of a refractive index modulation structure periodically distributed along the light propagation direction (i.e., a row of repeating stripes of equal width and spacing). It is used to provide feedback coupling and wavelength selection functions. Specifically, the first front grating layer 12 and the first rear grating layer 14 both use the sampling grating on their surfaces to reflect light in a specific wavelength band (i.e., generate Bragg reflection), so that it couples with the stimulated emission light generated by the first gain layer 13 to form the feedback loop required for laser oscillation. The sampling periods of the first front grating layer 12 and the first rear grating layer 14 are different, and the comb-shaped reflection spectra generated by the two have different peak spacings. Using the principle of coherent enhancement interference, only when the reflection peaks of the two coincide at a specific wavelength does that wavelength obtain the highest reflection feedback, thereby achieving precise selection of the target lasing wavelength. The functions of the second front grating layer 22 and the second rear grating layer 24 are the same as those of the first front grating layer 12 and the first rear grating layer 14, respectively, and will not be described in detail here. The comb-shaped reflection spectrum ranges of the first front grating layer 12 and the first rear grating layer 14 both cover the C-band (i.e., the overlapping reflection peaks cover 1530nm-1575nm, which is the C-band wavelength range), enabling the first laser unit to accurately select and tune the C-band lasing wavelengths; the comb-shaped reflection spectrum ranges of the second front grating layer 22 and the second rear grating layer 24 both cover the L-band (i.e., the overlapping reflection peaks cover 1575nm-1630nm, which is the L-band wavelength range), enabling the second laser unit to accurately select and tune the L-band lasing wavelengths.

[0055] Step 4: Grafting capping material and contact layer material sequentially from bottom to top in the combiner region, waveguide region, and two unit laser regions. For each unit laser region, the capping material and contact layer material 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 corresponding unit laser region.

[0056] Specifically, capping material and contact layer material are grown sequentially from bottom to top over the entire substrate 50. A silicon dioxide thin film is used to cover the combiner region, waveguide region, and two unit laser regions. The capping material and contact layer material in other areas of the substrate 50 are selectively removed to reduce electrical and optical crosstalk between array units. Then, the silicon dioxide thin film is removed to form a third capping layer 32 and a third contact layer 33 in the waveguide region, and a fourth capping layer 42 and a fourth contact layer 43 in the combiner region. For each unit laser region, a transverse strip-shaped region is first divided at the center of the upper surface of the contact layer material, and then covered with a silicon dioxide thin film. The wave combiner region, waveguide region, and two unit laser regions are divided into transverse strip regions. Then, the capping material and contact layer material in each unit laser region are subjected to SiCl4 gas dry etching to form a first shallow ridge structure in the first unit laser region and a second shallow ridge structure in the second unit laser region. The etching depth is controlled within the range of the capping material and contact layer material, without penetrating the capping material to the material layer below it. Then, the two side surfaces of the first and second shallow ridge structures 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 silicon dioxide film is removed.

[0057] The first shallow ridge structure is laterally distributed at the center of the upper surface of the functional layer composed of the first amplifier layer 11, the first front grating layer 12, the first gain layer 13 and the first rear grating layer 14; the second shallow ridge structure is laterally distributed at the center of the upper surface of the functional layer composed of the second amplifier layer 21, the second front grating layer 22, the second gain layer 23 and the second rear grating layer 24.

[0058] For the first unit laser region, first electrical isolation trenches 161 are etched on the first contact layer 16 between the amplifier region and the front grating region, the front grating region and the gain region, and the gain region and the rear grating region, respectively, to form electrical isolation between the amplifier region and the front grating region, the front grating region and the gain region, and the gain region and the rear grating region, so as to avoid current interference between the functional regions and ensure independent driving and independent tuning of each region; for the second unit laser region, the same etching operation is performed to form a second electrical isolation trench.

[0059] It should be noted that when etching the electrical isolation trench, a patterned mask corresponding to the electrical isolation trench can be formed first by photolithography, and then the electrical isolation trench can be etched on the electrical contact layer between adjacent areas using dry etching. Finally, the mask is removed.

[0060] Step 5: For each unit laser region, the passive material in the rear grating region is etched according to a predetermined cantilever beam pattern to form a cantilever beam structure, which includes a cantilever beam located directly below the shallow ridge waveguide structure and air slots symmetrically distributed on both sides.

[0061] Specifically, for the first unit laser region, two strip-shaped regions corresponding to the air slots are first divided on the upper surface of the first rear grating layer 14 corresponding to the rear grating region within it. These two strip-shaped regions are symmetrically distributed on both sides near the first shallow ridge waveguide structure and arranged parallel to the first shallow ridge waveguide structure. Then, two similar strip-shaped regions are divided on the upper surface of the second rear grating layer 24 corresponding to the rear grating region in the second unit laser region. A mask with a cantilevered strip pattern is then fabricated over the entire substrate 50 using photolithography. This mask is used to cover all strip-shaped regions on the substrate 50. In other areas, reactive ion etching and hydrobromic acid etching are used to remove the passive material corresponding to all strip regions. The etching depth is controlled within the passive material corresponding to the back grating region and does not penetrate the passive material to the substrate 50 below it. This forms a first cantilever beam structure in the first unit laser region, consisting of a central cantilever beam 141 and symmetrical air slots 142 on both sides. At the same time, a second cantilever beam structure identical to the first cantilever beam structure is formed in the second unit laser region. The width of the upper surface of the cantilever beam 141 is greater than the width of the lower surface of the first shallow ridge waveguide structure.

[0062] It should be noted that the upper surface of the cantilever beam 141 is 5 micrometers wider than the lower surface of the shallow ridge waveguide structure, and the air slot 142 is an inner hexagonal slot structure, such as... Figure 6 The diagram shown is a side section of the cantilever beam structure. The cantilever beam 141 is an integral structure that is wide at both ends and narrow in the middle.

[0063] Step 6: For each unit laser region, a P-side electrode is fabricated on the contact layer material corresponding to the amplifier region, the front grating region, and the gain region, respectively. A heating electrode is fabricated on the contact layer material corresponding to the rear grating region, and an N-side electrode is fabricated under the substrate 50.

[0064] Specifically, firstly, first P-surface electrodes 17 are fabricated above the first contact layer 16 corresponding to the amplifier region, front grating region, and gain region within the first unit laser region, and simultaneously, second P-surface electrodes 27 are fabricated above the second contact layer 26 corresponding to the amplifier region, front grating region, and gain region within the first unit laser region. Then, a first heating electrode 18 is fabricated above the first contact layer 16 corresponding to the rear grating region within the first unit laser region, and simultaneously, a second heating electrode 28 is fabricated above the second contact layer 26 corresponding to the rear grating region within the second unit laser region. Finally, the substrate 50 is thinned below, and N-surface electrodes 19 are fabricated on the entire surface to provide a common current loop for the entire device.

[0065] The middle part of the first heating electrode 18 is located above the first shallow ridge waveguide structure. The two ends of the first heating electrode 18 are a positive electrode 181 and a negative electrode 182, respectively. The positive electrode 181 and the negative electrode 182 are used to connect to the positive and negative terminals of an external power supply, respectively.

[0066] In this embodiment, under the InP-based material system, the substrate 50 is an N-type InP substrate; the amplifier layer and gain layer of the two laser units are made of InGaAsP (indium gallium arsenide phosphide) active material, the front and rear grating layers, waveguide layers and combiner layers are made of InGaAsP passive material, the capping layer 13 is made of InP material, and the contact layer 14 is made of 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.

[0067] It should be noted that the fabrication method provided by this invention solves the problems of fabrication yield, thermal field coupling, and power consumption control of ultra-wideband chips in the prior art through the synergistic design of different wavelength band spectrum division and control and micro-nano thermal isolation technology. The method of this invention effectively solves the fabrication bottleneck of single laser gain bandwidth by parallel integration of different wavelength band lasers. Traditional single devices are difficult to stably cover bandwidths exceeding 60nm. The method of this invention constructs two laser units covering the C-band (1530nm-1575nm) and L-band (1575nm-1630nm) respectively on the same substrate through regional docking growth and differentiated grating etching. This fabrication strategy avoids the device quality degradation problem caused by forcibly expanding the tuning range of a single laser tube, ensuring that each band is within the controlled optimal process window, and solving the problems of reduced tuning range and unstable operation caused by process deviations.

[0068] This invention achieves deep thermal decoupling of multi-source integrated circuits by introducing cantilever beam micro-nano etching. Traditional processes cannot cut off the heat conduction path of the substrate, leading to difficulties in wavelength locking. This invention precisely fabricates a cantilever beam structure with air grooves below the rear grating region, which is equivalent to building a thermal physical circuit on a continuous substrate. This allows the device to utilize the extremely low thermal conductivity of air to precisely limit the temperature rise generated by thermal tuning within the micro-nano scale of the cantilever beam space. Combined with shallow ridge waveguides, this not only achieves efficient carrier confinement but also solves the problem of thermal crosstalk in multi-source monolithic integration. This enables completely independent decoupling control of the two lasers in the subsequent tuning and calibration process, significantly improving the accuracy and reliability of wavelength control. Meanwhile, thanks to the extremely small heat capacity of the cantilever beam and the precise guidance of current by the shallow ridge structure, the Joule heat generated by the heating electrode can directly act on the grating layer without overcoming the "heat sink" effect generated by the substrate in the traditional solution. The device prepared by the method of this invention only requires a very small driving power to trigger the rapid response of the material's refractive index, which greatly reduces power consumption. Moreover, through the integrated fabrication process of the on-chip multiplexer, the cumbersome mechanical coupling and alignment processes mentioned in the background technology are eliminated. While achieving smooth switching across the entire wavelength range of 1530nm to 1630nm, the chip is ensured to have extremely high integration and low loss characteristics.

[0069] The transmitting chip prepared by the method in this embodiment includes a multiplexer 3, a waveguide structure 4, and a first laser unit 1 and a second laser unit 2 arranged in parallel. The multiplexer, the waveguide structure, and the two laser units are respectively disposed on the same substrate 50. The waveguide structure includes two input branches and a single output branch. The two laser units are respectively connected to the two input branches of the waveguide structure and coupled to the multiplexer via their single output branch.

[0070] The first laser unit includes a first amplifier layer 11, a first front grating layer 12, a first gain layer 13, a first rear grating layer 14, a first capping layer 15, and a first contact layer 16. The second laser unit includes a second amplifier layer 21, a second front grating layer 22, a second gain layer 23, a second rear grating layer 24, a second capping layer, and a second contact layer. Sampling gratings with a first sampling period and a second sampling period are respectively etched on the upper ends of the first front grating layer 12 and the first rear grating layer 14. Sampling gratings with a third sampling period and a fourth sampling period are respectively etched on the upper ends of the second front grating layer 23 and the second rear grating layer 24. The operating wavelengths of the first laser unit and the second laser unit are continuously distributed and jointly cover the C-band and the L-band.

[0071] The first capping layer 15 and the first contact layer 16 together constitute the first shallow ridge waveguide structure. The first rear grating layer 14 is provided with a first cantilever beam structure. The second capping layer and the second contact layer together constitute the second shallow ridge waveguide structure. The second rear grating layer 24 is provided with a first cantilever beam structure.

[0072] The first amplifier layer 11, the first front grating layer 12, the first gain layer 13, and the first rear grating layer 14 are arranged closely above the substrate 50 in a preset direction. The first cover layer 15 and the first contact layer 16 are arranged from bottom to top above the functional layer composed of the first amplifier layer 11, the first front grating layer 12, the first gain layer 13, and the first rear grating layer 14.

[0073] The first shallow ridge waveguide structure is formed by etching the entire first capping layer 15 and the first contact layer 16 according to a predetermined ridge pattern, and it is laterally disposed at the center of the upper surface of the functional layer composed of the first amplifier layer 11, the first front grating layer 12, the first gain layer 13, and the first rear grating layer 14.

[0074] A first cantilever beam structure is provided in the first rear grating layer 14. The first cantilever beam structure includes a cantilever beam 141 and air slots 142 symmetrically distributed on both sides. The cantilever beam 141 is located below the first shallow ridge waveguide structure and is formed by etching the first rear grating layer 14 located below the first shallow ridge waveguide structure according to a predetermined cantilever pattern.

[0075] The first gain layer 13 is disposed in the gain region of the first unit laser region and is used to provide a light source and gain medium for the first laser unit to emit light. It generates photon gain through injection current, enabling the device to emit tunable light signals.

[0076] The first gain layer 13 comprises, from bottom to top, a first lower confinement layer 131, a first multi-quantum well layer 132, and a first upper confinement layer 133. The first multi-quantum well layer 132 is an active layer that provides laser gain. The first lower confinement layer 131 and the first upper confinement layer 133 are used to form the lower and upper potential barriers of the quantum well, respectively, to restrict the movement of charge carriers in the quantum well, prevent their diffusion, and ensure the stability of the optical field and the distribution of charge carriers.

[0077] The first amplifier layer 11 is located in the amplifier area of ​​the first unit laser region and is used to perform power compensation and amplification on the optical signal output by the first laser unit. It achieves the preset intensity of device output power by injecting bias current to generate stimulated emission and improves the signal-to-noise ratio of the system.

[0078] The first amplifier layer 11 includes, from bottom to top, a second lower confinement layer 111, a second multiple quantum well layer 112, and a second upper confinement layer 113. The second multiple quantum well layer 112 serves as an optical amplification medium, increasing the photon density passing through the region through stimulated emission to achieve optical power gain. The second lower confinement layer 111 and the second upper confinement layer 113 are used to form the lower and upper potential barriers of the quantum well, respectively, to restrict the movement of charge carriers within the quantum well, improve the overlap efficiency between charge carriers and the optical field, and ensure the linearity and stability of the amplification gain.

[0079] The first front grating layer 12 and the first rear grating layer 14 are respectively disposed in the front grating region and the rear grating region of the first unit laser region by a docking growth method; sampling gratings with a first sampling period and a second sampling period are respectively etched on the top of the first front grating layer 12 and the first rear grating layer 14. The sampling gratings are composed of refractive index modulation structures periodically distributed along the light propagation direction, which are used to provide feedback coupling and wavelength selection functions.

[0080] The first cantilever beam structure is disposed in the region material layer of the first rear grating layer 14, wherein the cantilever beam 141 is laterally disposed directly below the shallow ridge waveguide structure, and the cantilever beam 141 is distributed parallel to the air slots 142 on both sides thereof.

[0081] The first capping layer 15 is used to provide a refractive index difference in the vertical direction to constrain the optical signal, so that the optical field is concentrated in the waveguide center region where the first amplifier layer 11, the first front grating layer 12, the first gain layer 13 and the first rear grating layer 14 are located, in order to reduce light leakage and propagation loss.

[0082] The first contact layer 16 is used to achieve good ohmic contact; a first electrical isolation trench 161 is also etched on the first contact layer 16. The first electrical isolation trench 161 is located between the first amplifier layer 11 and the first front grating layer 12, the first front grating layer 12 and the first gain layer 13, and the first gain layer 13 and the first rear grating layer 14, and is used to electrically isolate two adjacent regions.

[0083] A first P-side electrode 17 is disposed above the first contact layer 16 corresponding to the first amplifier layer 11, the first front grating layer 12 and the first gain layer 13, respectively; a first heating electrode 18 is disposed above the first contact layer 16 corresponding to the first rear grating layer 14; and an N-side electrode 19 is disposed below the substrate 50 after thinning treatment.

[0084] The P-side electrode corresponding to the first amplifier layer 11 is used to inject bias current into the first amplifier layer 11 to adjust its gain, compensate for the loss of optical signal during transmission, and improve the output optical power. The P-side electrode corresponding to the first front grating layer 12 is used to inject tuning current into the first front grating layer 12 to change its refractive index, thereby realizing the control of the position of the front grating reflection spectrum. The P-side electrode corresponding to the first gain layer 13 is used to connect the driving current to the first gain layer 13 to achieve stable optical output. The first heating electrode 18 corresponding to the first rear grating layer 14 has its middle part located above the first shallow ridge waveguide structure. The two ends of the first heating electrode 18 are a positive electrode 181 and a negative electrode 182, respectively. The positive electrode 181 and the negative electrode 182 are used to connect to the positive and negative terminals of the external power supply, respectively. After the first heating electrode 18 is energized, it provides local heating power to the first rear grating layer 14 below through the first shallow ridge waveguide structure to change its refractive index and reflection phase, thereby realizing fine wavelength tuning of the output optical signal.

[0085] After thinning, N-face electrodes 19 are formed on the entire surface of the substrate 50. The N-face electrodes 19 are used to provide a common current loop for the entire device.

[0086] The second amplifier layer 21, the second front grating layer 22, the second gain layer 23, and the second rear grating layer 24 are arranged closely in sequence above the substrate 50 in a preset direction. The second cover layer and the second contact layer are arranged from bottom to top above the functional layer composed of the second amplifier layer 21, the second front grating layer 22, the second gain layer 23, and the second rear grating layer 24.

[0087] The fabrication method and spatial structure of the second shallow ridge waveguide structure are the same as those of the first shallow ridge waveguide structure, and will not be described again here. The second shallow ridge waveguide structure is horizontally positioned at the center of the upper surface of the functional layer composed of the second amplifier layer 21, the second front grating layer 22, the second gain layer 23, and the second rear grating layer 24.

[0088] The second rear grating layer 24 is provided with a second cantilever beam structure. The fabrication method and spatial structure of the second cantilever beam structure are the same as those of the first cantilever beam structure. The second gain layer 23 is provided in the gain region of the second unit laser region. Its spatial structure is the same as that of the first gain layer 13. The second amplifier layer 21 is provided in the amplifier region of the second unit laser region. Its spatial structure is the same as that of the first amplifier layer 11.

[0089] The second front grating layer 22 and the second rear grating layer 24 are respectively disposed in the front grating region and the rear grating region of the second unit laser region by a docking growth method; sampling gratings with a third sampling period and a fourth sampling period are respectively etched above the second front grating layer 22 and the second rear grating layer 24.

[0090] The second capping layer is used to provide a refractive index difference in the vertical direction, and the second contact layer is used to achieve good ohmic contact. A second electrical isolation trench is also etched on the second contact layer. The second electrical isolation trench is located between the second amplifier layer 21 and the second front grating layer 22, the second front grating layer 22 and the second gain layer 23, and the second gain layer 23 and the second rear grating layer 24, and is used to electrically isolate two adjacent regions.

[0091] A second P-surface electrode 27 is disposed above the second contact layer corresponding to the second amplifier layer 21, the second front grating layer 22, and the second gain layer 23, respectively, and a second heating electrode 28 is disposed above the second contact layer corresponding to the second rear grating layer 24.

[0092] The second heating electrode 28 corresponding to the second rear grating layer 24 has its middle part located above the second shallow ridge waveguide structure, with positive and negative electrodes at both ends for connecting to the positive and negative terminals of an external power supply. Similarly, when the second heating electrode 28 is energized, it provides local heating power to the second rear grating layer 24 below through the second shallow ridge waveguide structure to change its refractive index and reflection phase, thereby achieving fine wavelength tuning of the output optical signal.

[0093] The waveguide structure is disposed in the Y-shaped waveguide region of the substrate 50, and includes a waveguide layer 31, a third capping layer 32 and a third contact layer 33 from bottom to top. The waveguide structure is formed by etching the capping layer and contact layer materials disposed in and around the waveguide region according to a predetermined Y-shaped waveguide pattern.

[0094] The multiplexer is disposed in the multiplexer region of the substrate 50, and includes, from bottom to top, a multiplexer layer 41, a fourth capping layer 42 and a fourth contact layer 43. The multiplexer is formed by etching the capping layer and contact layer materials disposed in and around the multiplexer region according to a predetermined multiplexer pattern.

[0095] Example 1:

[0096] A chip fabricated using the method of this invention was subjected to power consumption and crosstalk tests. The substrate was an N-type InP, the active layer was made of InGaAsP material, and each laser unit in the fabricated chip had the same cantilever beam and air slot physical isolation structure.

[0097] The first laser unit was selected for power consumption testing. A steady-state current of 80mA was injected into the gain region. An initial current of 0mA was applied to the heating electrode, increasing to 50mA in 1mA increments. At each current point, the peak wavelength was read using an OSA spectrometer (such as an Ando AQ6317 or a higher precision model). Simultaneously, the source meter synchronously records the voltage across the heating electrode and calculates the power consumption at a specific point when the wavelength undergoes a jump (such as jumping from one channel to the next, i.e., one channel spacing). Experimental records show that when the heating current increases from 0mA to 35mA, the voltage increases linearly from 0V to approximately 1.4V. The instantaneous power consumption at 35mA is calculated to be 49mW. At this point, the lasing wavelength achieves 12nm wavelength tuning. In contrast, if the conventional chip in the reference group were to achieve the same 12nm tuning, an 80mA current (approximately 3.2V) would be applied, resulting in a power consumption of 256mW. Therefore, this scheme significantly reduces power consumption.

[0098] Two laser units were selected for crosstalk testing; simultaneously, 80mA of drive current was injected into the gain region of the first laser unit (C-band), and its heating electrode was adjusted to lock it at the center reference wavelength. =1550.00nm, keeping the state of the first laser unit unchanged, a scanning current from 0mA to 40mA is applied to the heating electrode of the second laser unit (L band). The wavelength of the second laser unit shifts from 1575nm to 1630nm, and OSA is used for real-time monitoring. The center position; experimental results show that when the second laser unit generates the highest power consumption, the center wavelength of the first laser unit is at the center position; Only a tiny drift of about 0.03 nm was generated, which is much smaller than the channel offset threshold of 0.1 nm in the ITU-T standard. This proves that the physical circuit breaking of the cantilever beam and the extremely high thermal resistance of the air duct effectively block the lateral diffusion of heat flow from the second laser unit to the first laser unit, thus achieving decoupled control.

[0099] The steps in this invention can be adjusted, combined, or deleted according to actual needs.

[0100] The units in the device of the present invention can be merged, divided, or reduced according to actual needs.

[0101] 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.

[0102] 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.

[0103] 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 for fabricating an emitting chip covering C-band and L-band light, characterized in that, The method includes: Step 1, prepare a substrate (50), divide a combiner region, a waveguide region and two parallel unit laser regions on the substrate (50), and divide an amplifier region, a front grating region, a gain region and a rear grating region in each unit laser region in sequence. The waveguide region includes two input paths and a single output path. The two input paths are respectively connected to the amplifier regions of the two unit laser regions, and the single output path is connected to the combiner region. Step 2, grow active material on substrate (50), cover amplifier region and gain region in two unit laser regions with mask, and selectively remove active material in other regions to form amplifier layer and gain layer in each unit laser region; Step 3: On the substrate (50), passive materials are grown in other areas except for the amplifier region and the gain region. The mask is removed, and sampling gratings with different sampling periods are fabricated on the passive materials in the front and rear grating regions of each unit laser region to form a patterned front grating layer and a rear grating layer in each unit laser region. The operating wavelength of the first laser unit covers the C-band, and the operating wavelength of the second laser unit covers the L-band. Step 4: In the combiner region, waveguide region and two unit laser regions, capping material and contact layer material are grown sequentially from bottom to top. For each unit laser region, the inner capping material and contact layer material are etched as a whole according to the predetermined ridge pattern to form a shallow ridge waveguide structure. The shallow ridge waveguide structure is laterally distributed in the center of the corresponding unit laser region. Step 5: For each unit laser region, the passive material in the rear grating region is etched according to the predetermined cantilever beam pattern to form a cantilever beam structure. The cantilever beam structure includes a cantilever beam located directly below the shallow ridge waveguide structure and air slots symmetrically distributed on both sides. Step 6: For each unit laser region, a P-side electrode is fabricated on the contact layer material corresponding to the amplifier region, the front grating region and the gain region, a heating electrode is fabricated on the contact layer material corresponding to the rear grating region, and an N-side electrode is fabricated under the substrate (50).

2. The method for fabricating an emitting chip covering C-band and L-band light as described in claim 1, characterized in that, Step 2 specifically includes: Active materials are grown layer by layer from bottom to top on the substrate (50). A mask is used to cover the amplifier region and gain region in each unit laser region. Then, active materials in other regions outside the amplifier region and gain region are removed by dry etching. The active materials remaining after etching are removed by wet etching with sulfuric acid solution to form a first amplifier layer (11) and a first gain layer (13) in the first unit laser region. A second amplifier layer (21) and a second front grating layer (22) are formed in the first unit laser region.

3. The method for fabricating an emitting chip covering C-band and L-band light as described in claim 2, characterized in that, Step 2 further includes: setting a first gain layer (13) in the gain region of the first unit laser region, which includes a first lower confinement layer (131), a first multiple quantum well layer (132) and a first upper confinement layer (133) from bottom to top; setting a first amplifier layer (11) in the amplifier region of the first unit laser region, which includes a second lower confinement layer (111), a second multiple quantum well layer (112) and a second upper confinement layer (113) from bottom to top.

4. The method for fabricating an emitting chip covering C-band and L-band light as described in claim 1, characterized in that, Step 3 specifically includes: Passive materials are grown in the front and rear grating regions of the two unit laser regions and in the region consisting of the combiner region and the waveguide region using a metal-organic chemical vapor deposition apparatus. The mask is removed, and sampling gratings with a first sampling period and a second sampling period are fabricated on the passive materials of the front and rear grating regions in the first unit laser region, respectively, to form a patterned first front grating layer (12) and a first rear grating layer (14) in the first unit laser region. Sampling gratings with a third sampling period and a fourth sampling period are fabricated on the passive materials of the front and rear grating regions in the second unit laser region, respectively, to form a patterned second front grating layer (22) and a second rear grating layer (24) in the second unit laser region. The combiner region, the waveguide region and all unit laser regions are covered with a mask, and passive materials in other regions on the substrate (50) are selectively removed to form a waveguide layer (31) in the waveguide region and a combiner layer (41) in the combiner region.

5. The method for fabricating an emitting chip covering C-band and L-band light as described in claim 4, characterized in that, In step 3, the values ​​of the first sampling period and the second sampling period are both configured such that the comb-shaped reflection spectrum range of the first front grating layer (12) and the first rear grating layer (14) both cover the C-band; the values ​​of the third sampling period and the fourth sampling period are both configured such that the comb-shaped reflection spectrum range of the second front grating layer (22) and the second rear grating layer (24) both cover the L-band. The photofluorescence wavelength of the passive material is 100 nm shorter than that of the first quantum well layer (132) and the second quantum well layer (112).

6. The method for fabricating an emitting chip covering C-band and L-band light as described in claim 1, characterized in that, Step 4 specifically includes: A capping layer material and a contact layer material are grown sequentially from bottom to top over the entire substrate (50). A mask is used to cover the combiner region, the waveguide region, and the two unit laser regions. The capping layer material and the contact layer material in other regions of the substrate (50) are selectively removed. Then the mask is removed to form a third capping layer (32) and a third contact layer (33) in the waveguide region and a fourth capping layer (42) and a fourth contact layer (43) in the combiner region. For each unit laser region, a transverse strip-shaped region is first defined at the center of the upper surface of the contact layer material. A mask is used to cover the wave combiner region, waveguide region, and the transverse strip-shaped region in both unit laser regions. Then, the capping material and contact layer material in each unit laser region are subjected to SiCl4 gas dry etching to form a first shallow ridge structure in the first unit laser region and a second shallow ridge structure in the second unit laser region. The etching depth is controlled within the range of the capping material and contact layer material. Then, HCl solution wet etching is used to modify the two side surfaces of the first and second shallow ridge structures. Finally, the mask is removed.

7. The method for fabricating an emitting chip covering C-band and L-band light as described in claim 6, characterized in that, Step 4 further includes: for the first unit laser region, etching an electrical isolation trench (161) above the first contact layer (16) between its amplifier region and the front grating region, the front grating region and the gain region, and the gain region and the rear grating region, respectively; for the second unit laser region, performing the same etching operation to form a second electrical isolation trench.

8. The method for fabricating an emitting chip covering C-band and L-band light as described in claim 1, characterized in that, Step 4 specifically includes: For the first unit laser region, two strip regions corresponding to the air slots are first divided on the upper surface of the first back grating layer (14) corresponding to the back grating region. These two strip regions are symmetrically distributed on both sides of the first shallow ridge waveguide structure and arranged parallel to the first shallow ridge waveguide structure. Then, the same two strip regions are divided on the upper surface of the second back grating layer (24) in the second unit laser region. A mask with a cantilever strip pattern is made on the entire substrate (50). The mask is used to cover the other areas on the substrate (50) except for all the strip regions. The passive material corresponding to all the strip regions is removed by reactive ion etching equipment and hydrobromic acid etching. The etching depth is controlled within the passive material corresponding to the back grating region, so as to form a cantilever beam structure consisting of a central cantilever beam and air slots symmetrically distributed on both sides in the two unit laser regions.

9. The method for fabricating an emitting chip covering C-band and L-band light as described in claim 1, characterized in that, Step 6 specifically includes: First, a first P-surface electrode (17) is fabricated above the first contact layer (16) corresponding to the amplifier region, front grating region and gain region in the first unit laser region. Simultaneously, a second P-surface electrode (27) is fabricated above the second contact layer (26) corresponding to the amplifier region, front grating region and gain region in the first unit laser region. Then, a first heating electrode (18) is fabricated above the first contact layer (16) corresponding to the rear grating region in the first unit laser region. Simultaneously, a second heating electrode (28) is fabricated above the second contact layer (26) corresponding to the rear grating region in the second unit laser region.

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