A multi-wavelength array laser and its preparation method

Abstract

The present invention provides a multi-wavelength array laser and its fabrication method. The laser comprises at least two laser units arranged in parallel on the same substrate, with an electrode isolation region between adjacent laser units. The at least two laser units have different wavelengths. The laser comprises a primary epitaxial layer, a grating region layer, and a secondary epitaxial layer. The primary epitaxial layer is located on the substrate; the grating region layer is located on the primary epitaxial layer and includes multiple grating units, each of which is fabricated from high-order phase-shifted gratings or high-order pitch-adjusted gratings. Each grating unit corresponds to one laser unit, and each grating unit has a different grating period, resulting in different wavelengths. The secondary epitaxial layer is located on the grating region layer. The laser utilizes a high-order grating, which improves the process tolerance of grating fabrication, shortens the processing cycle, and facilitates precise wavelength control. Furthermore, the use of a single substrate enables monolithic integration of multiple laser units.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor lasers, and in particular to a multi-wavelength array laser and a preparation method thereof. Background Art

[0002] In recent years, optical input / output (I / O) technology has emerged as a new link technology, promoting low-power, high-density interconnection and meeting the high-bandwidth transmission rates required by fields such as artificial intelligence, the Internet of Things, and communications. Dense wavelength division multiplexing (DWDM) systems have emerged as an excellent solution due to their ability to meet the high-bandwidth density requirements of optical I / O links. The core component of this optical I / O technology is a multi-wavelength array laser (MWL), whose wavelengths must be strictly aligned with the DWDM system to achieve bandwidth scalability and enable the transmission of high-speed, massive amounts of information.

[0003] Currently available multi-wavelength array lasers include frequency comb lasers, mode-locked lasers, and distributed feedback (DFB) laser arrays. DFB laser arrays are widely used due to their excellent mode stability, simple operation mechanism, and high output power. However, when the wavelength channel spacing is small, the grating period needs to achieve sub-nanometer precision, making the preparation of multi-wavelength array lasers that meet these requirements extremely challenging. Summary of the Invention

[0004] The present invention aims to at least solve the technical problems existing in the prior art. To this end, in a first aspect, the present invention provides a multi-wavelength array laser, wherein the laser comprises at least two laser units arranged in parallel on the same substrate, with an electrode isolation region between two adjacent laser units; the at least two laser units have different wavelengths; and the substrate is an N-type InP substrate.

[0005] The laser comprises a primary epitaxial layer, a grating region layer and a secondary epitaxial layer;

[0006] The primary epitaxy is located on the substrate, and the primary epitaxy includes, from bottom to top, a buffer layer, a lower confinement layer, a quantum well active layer, and an upper confinement layer, wherein the thickness of the lower confinement layer is greater than that of the upper confinement layer;

[0007] The grating region layer is located on the primary epitaxial layer and includes a plurality of grating units, each of which is made of a high-order phase-shift grating or a high-order pitch-adjusted grating; one grating unit corresponds to one laser unit, and each grating unit has a different grating period, and the different grating periods form different wavelengths;

[0008] The secondary epitaxy is located on the grating region layer, and includes an upper waveguide layer and an ohmic contact layer from bottom to top.

[0009] Optionally, the high-order phase-shift grating and the high-order pitch-adjustment grating are one of 2nd-order grating, 3rd-order grating, 4th-order grating and 5th-order grating; the duty cycle of the high-order phase-shift grating and the high-order pitch-adjustment grating is 0.3 to 0.8; and the thickness of the grating region layer is 20 to 50 nm.

[0010] Optionally, the phase shift region of the high-order phase shift grating adopts a λ / 4 phase shift, and the phase shift region is located at 1 / 3 to 1 / 4 of the laser cavity length and close to one side of the laser reflection surface.

[0011] Optionally, the output wavelength of each of the laser units is within the O-band or C-band range for optical communication, and the wavelength interval of each of the laser units is one of the following: 100 GHz, 200 GHz, 400 GHz, 800 GHz, or above 800 GHz.

[0012] Optionally, a light field adjustment layer composed of InGaAsP is embedded in the buffer layer, and the light field adjustment layer has at least one layer, and the thickness of each layer is 50 to 300 nm.

[0013] Optionally, the quantum well active layer is composed of InGaAsP or AlGaInAs, the gain spectrum of the quantum well active layer covers the wavelength range of the laser, and the number of alternations of quantum wells and barrier layers in the quantum well active layer is less than or equal to 3.

[0014] Optionally, the substrate is an n-type InP substrate; the n-pole of each laser unit is a common electrode, and the p-pole is controlled individually.

[0015] A second aspect of the present invention provides a method for preparing a multi-wavelength array laser, the method comprising:

[0016] Prepare a substrate, and deposit a primary epitaxial layer on the substrate, wherein the primary epitaxial layer includes, from bottom to top, a buffer layer, a lower confinement layer, a quantum well active layer, an upper confinement layer, and a grating layer, wherein the thickness of the lower confinement layer is greater than that of the upper confinement layer;

[0017] A grating region layer is prepared on the primary epitaxy using a high-order phase-shift grating or a high-order pitch-adjusted grating; the grating region layer includes a plurality of grating units, each of the grating units having a different grating period;

[0018] Depositing a secondary epitaxial layer on the grating region layer, wherein the secondary epitaxial layer includes a waveguide layer and an ohmic contact layer from bottom to top; performing waveguide etching on the secondary epitaxial layer using a back-end process, and depositing an insulating layer on the outer side of the secondary epitaxial layer;

[0019] A window is opened in the insulating layer, and a metal electrode is prepared at the position of the window.

[0020] Optionally, the waveguide etching adopts ridge waveguide etching; the material of the insulating layer is silicon dioxide;

[0021] The metal electrodes include an n-type electrode and a p-type electrode, wherein the n-type electrode is formed by electron beam evaporation and magnetron sputtering, and the p-type electrode is formed by electron beam evaporation and electroplating.

[0022] After the metal electrode is prepared, it is annealed at 300-500° C. for 2-10 minutes to form an ohmic contact layer between the metal electrode layer and the waveguide layer.

[0023] Optionally, the isolation paths between the p-type electrodes of the laser units are prepared by photolithography.

[0024] The beneficial effects of the technical solutions provided in the embodiments of the present application include at least:

[0025] An embodiment of the present invention provides a multi-wavelength array laser, characterized in that the laser includes at least two laser units arranged in parallel on the same substrate, with an electrode isolation region between two adjacent laser units; the at least two laser units have different wavelengths; the laser includes a primary epitaxial layer, a grating region layer, and a secondary epitaxial layer; the primary epitaxial layer is located on the substrate and includes, from bottom to top, a buffer layer, a lower confinement layer, a quantum well active layer, and an upper confinement layer, the thickness of the lower confinement layer being greater than the thickness of the upper confinement layer; the grating region layer is located on the primary epitaxial layer and includes a plurality of grating units, each of which is prepared from a high-order phase-shifted grating or a high-order pitch-adjusted grating; one grating unit corresponds to one laser unit, each grating unit has a different grating period, and the different grating periods form different wavelengths; the secondary epitaxial layer is located on the grating region layer and includes, from bottom to top, an upper waveguide layer and an ohmic contact layer. The laser uses high-order phase-shifted gratings or high-order pitch-adjusted gratings, which improves the process tolerance of grating preparation, shortens the processing cycle, and facilitates precise control of wavelength. In addition, the use of the same substrate enables monolithic integration of multiple laser units, providing an ideal on-chip multi-wavelength light source for large-scale photonic interconnection systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of the appearance of a multi-wavelength array laser provided in an embodiment of the present invention;

[0027] Figure 2 A schematic structural diagram of a multi-wavelength array laser provided in an embodiment of the present invention;

[0028] Figure 3 A spectrum diagram of a multi-wavelength array laser provided by an embodiment of the present invention;

[0029] Figure 4 A flowchart of a method for preparing a multi-wavelength array laser is provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0031] Figure 1 A schematic diagram of the appearance of a multi-wavelength array laser provided by an embodiment of the present invention.

[0032] like Figure 1 As shown in FIG, the laser comprises at least two laser units arranged in parallel on the same substrate. Figure 1 Laser unit 1, laser unit 2, laser unit . . . , laser unit n. Adjacent laser units are separated by an electrode isolation region. Each laser unit emits a different laser wavelength.

[0033] Each laser unit includes a primary epitaxial layer, a grating region layer and a secondary epitaxial layer.

[0034] Figure 2 A schematic structural diagram of a multi-wavelength array laser provided by an embodiment of the present invention.

[0035] like Figure 2 As shown, the primary epitaxy is located on the substrate, and the primary epitaxy includes a buffer layer, a lower confinement layer, a quantum well active layer, and an upper confinement layer from bottom to top, and the thickness of the lower confinement layer is greater than that of the upper confinement layer.

[0036] The buffer layer's primary functions include reducing lattice mismatch and improving material and interface quality, thereby enhancing the performance and reliability of semiconductor devices. The buffer layer contains a light field modulation layer composed of indium gallium arsenide phosphide (InGaAsP). The light field modulation layer consists of at least one layer, each 50 to 300 nm thick.

[0037] The quantum well active layer is composed of indium gallium arsenide phosphide (InGaAsP) or aluminum gallium indium arsenide (AlGaInAs), the gain spectrum of the quantum well active layer covers the wavelength range of the laser, and the number of alternations between quantum wells and barrier layers in the quantum well active layer is less than or equal to 3.

[0038] Confinement layers are divided into upper and lower confinement layers, located on the upper and lower surfaces of the quantum well active layer, respectively. These confinement layers limit current injection and light propagation, optimizing laser performance and stability. Confinement layers are typically formed by sandwiching a narrow bandgap material between two larger bandgap materials, such as AlGaAs or InGaAsP.

[0039] Array laser epitaxy can achieve monolithic integration using the same substrate.

[0040] The grating region layer, located above the primary epitaxial layer, includes multiple grating units. These grating units are fabricated from high-order phase-shifted gratings or high-order pitch-adjusted gratings. Each grating unit corresponds to one laser unit, and each grating unit has a different grating period, resulting in different wavelengths. If the grating region layer includes eight grating units, the multi-wavelength array laser comprises eight laser units.

[0041] Figure 3 This is a spectrum diagram of a multi-wavelength array laser provided by an embodiment of the present invention.

[0042] like Figure 3 As shown, the multi-wavelength laser includes eight wavelength laser units with a wavelength interval of 200 GHz.

[0043] By introducing high-order gratings, the process tolerance of grating processing can be improved, the processing time can be shortened, and the uniformity of wavelength spacing can be improved.

[0044] The secondary epitaxy is to deposit the waveguide layer and the ohmic contact layer in sequence on the grating region layer.

[0045] The waveguide layer's primary functions include controlling the direction of light propagation, wavelength selection, filtering, and light amplification, thereby improving the laser's output power and stability. The waveguide layer uses high-refractive-index materials (such as semiconductors like GaAs and InP) to confine and control light, allowing the optical signal to propagate and amplify along a specific direction, thereby achieving laser emission.

[0046] As the outermost protective structure, the ohmic contact layer prevents contamination and damage to the active layer and cladding during fabrication and operation, thereby improving the reliability and long-term stability of the laser. In some cases, the ohmic contact layer can also serve as a contact layer, forming a good ohmic contact with the electrode, further reducing contact resistance and improving the electrical performance of the laser.

[0047] As an optional embodiment, the high-order phase-shift grating and the high-order pitch-adjustment grating are one of a 2nd-order grating, a 3rd-order grating, a 4th-order grating, and a 5th-order grating; the duty cycle of the high-order phase-shift grating and the high-order pitch-adjustment grating is 0.3 to 0.8; and the thickness of the grating region layer is 20 to 50 nm.

[0048] High-order gratings can increase the grating period and improve process tolerance. High-order phase-shifted gratings introduce phase discontinuities into the high-order grating, creating an extremely narrow transmission window in the grating reflection spectrum.

[0049] A grating is composed of a large number of equally spaced reflective elements. The spacing and shape of these elements determine the grating's effect on light. High-order pitch-adjustable gratings modify the interference characteristics of light by adjusting their pitch—the distance between adjacent slits or reflective elements.

[0050] As an optional embodiment, the phase shift region of the high-order phase shift grating adopts a λ / 4 phase shift, and the phase shift region is located at 1 / 3 to 1 / 4 of the laser cavity length and close to one side of the laser reflection surface.

[0051] The introduction of phase-shift grating can improve the single-mode yield of laser.

[0052] As an optional embodiment, the output wavelength of each of the laser units is within the O-band or C-band range for optical communication, and the wavelength interval of each of the laser units is one of the following: 100 GHz, 200 GHz, 400 GHz, 800 GHz, and above 800 GHz.

[0053] The above-mentioned band range and wavelength interval comply with the Continuous Wavelength Division Multiplexing Multi-Source Agreement "CW-WDM MSA Technical Specifications Rev 1.0" standard.

[0054] As an optional embodiment, a light field adjustment layer composed of InGaAsP is embedded in the buffer layer, and the light field adjustment layer has at least one layer, and the thickness of each layer is 50 to 300 nm.

[0055] like Figure 2 As shown, the light field adjustment layer is located in the middle of the buffer layer. The light field adjustment layer can move the laser light field downward, reduce light transmission loss, and thus increase the laser output power.

[0056] As an optional embodiment, the quantum well active layer is composed of InGaAsP or AlGaInAs, the gain spectrum of the quantum well active layer covers the wavelength range of the laser, and the number of alternations of quantum wells and barrier layers in the quantum well active layer is less than or equal to 3.

[0057] The quantum well active layer is an artificial periodic structure formed by alternating ultrathin layers of two or more materials with different compositions or conductivity types. This structure enhances carrier injection into the active layer, thereby improving device performance. The periodicity of the quantum well active layer refers to the number of alternating quantum well and barrier layers within a quantum well structure. In this solution, the number of alternating quantum well and barrier layers is less than or equal to three.

[0058] As an optional embodiment, the substrate is an n-type InP substrate; the n-pole of each laser unit is a common electrode, and the p-pole is controlled separately.

[0059] N-type InP substrates are formed by doping indium phosphide (InP) with donor impurities (such as phosphorus or arsenic). Negatively charged free electrons serve as the primary charge carriers. N-type InP substrates offer good conductivity and high electron concentration, but relatively low electron mobility.

[0060] Specifically, the n-pole of each laser unit is a common electrode, and the p-electrode of each laser unit is controlled individually. Isolation paths are prepared between each p-electrode by photolithography. The isolation paths can achieve insulation between each unit laser so that they are not affected by each other.

[0061] In summary, an embodiment of the present invention provides a multi-wavelength array laser, characterized in that the laser includes at least two laser units arranged in parallel on the same substrate, and an electrode isolation region is formed between two adjacent laser units; the at least two laser units have different wavelengths; the laser includes a primary epitaxial layer, a grating region layer and a secondary epitaxial layer; the primary epitaxial layer is located on the substrate, and the primary epitaxial layer includes, from bottom to top, a buffer layer, a lower confinement layer, a quantum well active layer, and an upper confinement layer, and the thickness of the lower confinement layer is greater than the thickness of the upper confinement layer; the grating region layer is located on the primary epitaxial layer, and includes a plurality of grating units, and the grating units are prepared by high-order phase-shifted gratings or high-order pitch-adjusted gratings; one grating unit corresponds to one laser unit, and each grating unit has a different grating period, and the different grating periods form different wavelengths; the secondary epitaxial layer is located on the grating region layer, and includes, from bottom to top, an upper waveguide layer and an ohmic contact layer. The laser uses high-order phase-shifted gratings or high-order pitch-adjusted gratings, which improves the process tolerance of grating preparation, shortens the processing cycle, and facilitates precise control of wavelength. In addition, the use of the same substrate enables monolithic integration of multiple laser units, providing an ideal on-chip multi-wavelength light source for large-scale photonic interconnection systems.

[0062] Figure 4 A flowchart of a method for preparing a multi-wavelength array laser according to an embodiment of the present invention. Figure 4 As shown, the method includes:

[0063] Step 101: prepare a substrate and deposit a primary epitaxial layer on the substrate. The primary epitaxial layer includes a buffer layer, a lower confinement layer, a quantum well active layer, an upper confinement layer, and a grating layer from bottom to top. The thickness of the lower confinement layer is greater than that of the upper confinement layer.

[0064] Specifically, the substrate is an N-type InP substrate. N-type InP substrates include: N-type Sn-doped InP, N-type S-doped InP, and P-type Zn-doped InP. N-type Sn-doped InP is primarily used for laser diodes, N-type S-doped InP is used for laser diodes and photodetectors, and P-type Zn-doped InP is primarily used for high-power laser diodes. In the embodiments of the present invention, one of these substrates is selected for fabrication based on specific requirements.

[0065] Array laser epitaxy can achieve monolithic integration using the same substrate.

[0066] The buffer layer's primary functions include reducing lattice mismatch and improving material and interface quality, thereby enhancing the performance and reliability of semiconductor devices. The buffer layer contains a light field modulation layer composed of indium gallium arsenide phosphide (InGaAsP). The light field modulation layer consists of at least one layer, each 50 to 300 nm thick.

[0067] The quantum well active layer is composed of indium gallium arsenide phosphide (InGaAsP) or aluminum gallium indium arsenide (AlGaInAs), the gain spectrum of the quantum well active layer covers the wavelength range of the laser, and the number of alternations between quantum wells and barrier layers in the quantum well active layer is less than or equal to 3.

[0068] Confinement layers are divided into upper and lower confinement layers, located on the upper and lower surfaces of the quantum well active layer, respectively. These confinement layers limit current injection and light propagation, optimizing laser performance and stability. Confinement layers are typically formed by sandwiching a narrow bandgap material between two larger bandgap materials, such as AlGaAs / InGaAsP.

[0069] Step 102: Prepare a grating region layer on the primary epitaxy by using a high-order phase-shift grating or a high-order pitch-adjusted grating; the grating region layer includes a plurality of grating units, each of the grating units having a different grating period.

[0070] High-order gratings can increase the grating period and improve process tolerance. High-order phase-shifted gratings introduce phase discontinuities into the high-order grating, creating an extremely narrow transmission window in the grating reflection spectrum.

[0071] A grating is composed of a large number of equally spaced reflective elements. The spacing and shape of these elements determine the grating's effect on light. High-order pitch-adjustable gratings modify the interference characteristics of light by adjusting their pitch—the distance between adjacent slits or reflective elements.

[0072] The grating is prepared by electron beam exposure method with high process precision.

[0073] The grating region layer includes a plurality of grating units, each grating unit has a different grating period, and different grating periods form different wavelengths.

[0074] Step 103: depositing a secondary epitaxial layer on the grating region layer, wherein the secondary epitaxial layer includes a waveguide layer and an ohmic contact layer from bottom to top; performing waveguide etching on the secondary epitaxial layer using a back-end process, and depositing an insulating layer on the outside of the secondary epitaxial layer.

[0075] The main functions of the waveguide layer include controlling the propagation direction of light, wavelength selection and filtering, as well as achieving light amplification, thereby improving the output power and stability of the laser.

[0076] As the outermost protective structure, the ohmic contact layer can prevent the active layer and cladding from being contaminated and damaged during the preparation and operation process, thereby improving the reliability and long-term stability of the laser.

[0077] Waveguide etching is a process that removes material from the surface of electronic devices through chemical reactions, thereby forming microstructures. The principle is to use an etching solution to chemically react with the surface of the electronic device, removing the desired material and forming the desired microstructure. The waveguide etching process can control the etch depth and shape, thereby achieving precise processing of microstructures.

[0078] Before filling the metal electrode, an insulating layer must be deposited to isolate the electrical conduction between the filling metal and the silicon. Specifically, the insulating layer is deposited using silicon dioxide material.

[0079] Step 104: opening windows in the insulating layer and using the positions of the windows to prepare metal electrodes.

[0080] Insulation layer windowing refers to making a gap in the insulation layer so that the gap position is not covered by the solder mask layer so that a metal electrode can be welded at the gap position.

[0081] As an optional embodiment, the waveguide etching adopts ridge waveguide etching; the material of the insulating layer is silicon dioxide; the metal electrode includes an n-type electrode and a p-type electrode, wherein the n-type electrode adopts electron beam evaporation and magnetron sputtering process, and the p-type electrode adopts electron beam evaporation and electroplating process; after preparing the metal electrode, annealing is carried out at 300-500°C for 2-10 minutes to form an ohmic contact layer between the metal electrode layer and the waveguide layer.

[0082] Reference Figure 1 , indicating the location of the ridge waveguide.

[0083] In an embodiment of the present invention, a ridge waveguide etching method is as follows: a photoresist is applied to a planar waveguide sample, the photoresist is exposed to ultraviolet light or X-rays through a contact mask that defines the shape of the waveguide, and the photoresist is subsequently developed to form a pattern on the sample surface.

[0084] The metal electrodes include an n-type electrode and a p-type electrode, wherein the n-type electrode is formed by electron beam evaporation and magnetron sputtering, and the p-type electrode is formed by electron beam evaporation and electroplating.

[0085] Electron beam evaporation (EBE) is a physical vapor deposition (PVD) technology that is mainly used to evaporate materials by heating them with an electron beam under vacuum conditions, causing them to vaporize and condense on a substrate to form a thin film.

[0086] Magnetron sputtering is a physical vapor deposition (PVD) method that adds magnets to the back of the target. By forming an interactive electromagnetic field in the chamber, the electron movement path is extended, thereby increasing the plasma concentration and achieving more deposition.

[0087] The electroplating process is the process of plating a thin layer of other metals or alloys on certain metal surfaces using the principle of electrolysis. It is a process of using electrolysis to attach a layer of metal film to the surface of metal or other material parts.

[0088] As an optional embodiment, the isolation paths between the p-type electrodes of the laser units are prepared by photolithography.

[0089] Specifically, photolithography is a major process in the production of planar transistors and integrated circuits. It is a processing technique for opening holes in a mask (such as silicon dioxide) on the surface of a semiconductor wafer to allow for the localized diffusion of impurities.

[0090] Isolation paths are prepared between the p-type electrodes of each laser unit through a photolithography process. The isolation paths can achieve insulation between the laser units so that they are not affected by each other.

[0091] In summary, the method for preparing a multi-wavelength array laser provided by an embodiment of the present invention comprises preparing a substrate and depositing a primary epitaxial layer on the substrate, wherein the primary epitaxial layer comprises, from bottom to top, a buffer layer, a lower confinement layer, a quantum well active layer, an upper confinement layer, and a grating layer, and the thickness of the lower confinement layer is greater than that of the upper confinement layer; a grating region layer is prepared on the primary epitaxial layer using a high-order phase-shift grating or a high-order pitch-adjusted grating; the grating region layer comprises a plurality of grating units, each of the grating units having a different grating period; a secondary epitaxial layer is deposited on the grating region layer, wherein the secondary epitaxial layer comprises, from bottom to top, a waveguide layer and an ohmic contact layer; waveguide etching is performed on the secondary epitaxial layer using a back-end process, and an insulating layer is deposited on the outside of the secondary epitaxial layer; a window is opened in the insulating layer, and a metal electrode is prepared using the position of the window. The laser uses high-order phase-shifted gratings or high-order pitch-adjusted gratings, which improves the process tolerance of grating preparation, shortens the processing cycle, and facilitates precise control of wavelength. In addition, the use of the same substrate enables monolithic integration of multiple laser units, providing an ideal on-chip multi-wavelength light source for large-scale photonic interconnection systems.

[0092] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0093] The above embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A multi-wavelength array laser, characterized in that: The laser comprises at least two laser units arranged in parallel on the same substrate, with an electrode isolation region between two adjacent laser units; the at least two laser units have different wavelengths; The laser comprises a primary epitaxial layer, a grating region layer and a secondary epitaxial layer; The primary epitaxy is located on the substrate, and the primary epitaxy includes, from bottom to top, a buffer layer, a lower confinement layer, a quantum well active layer, and an upper confinement layer, wherein the thickness of the lower confinement layer is greater than that of the upper confinement layer; The grating region layer is located on the primary epitaxial layer and includes a plurality of grating units, each of which is made of a high-order phase-shift grating or a high-order pitch-adjusted grating; one grating unit corresponds to one laser unit, and each grating unit has a different grating period, and the different grating periods form different wavelengths; The secondary epitaxy is located on the grating region layer, and includes an upper waveguide layer and an ohmic contact layer from bottom to top.

2. The laser according to claim 1, characterized in that The high-order phase-shift grating and the high-order pitch-adjusted grating are one of 2nd-order grating, 3rd-order grating, 4th-order grating and 5th-order grating; the duty cycle of the high-order phase-shift grating and the high-order pitch-adjusted grating is 0.3-0.8; the thickness of the grating region layer is 20-50nm.

3. The laser according to claim 1, characterized in that The phase shift region of the high-order phase shift grating adopts a λ / 4 phase shift, and the phase shift region is located at 1 / 3 to 1 / 4 of the laser cavity length and close to one side of the laser reflection surface.

4. The laser according to claim 1, characterized in that The output wavelength of each of the laser units is within the O-band or C-band range for optical communication, and the wavelength interval of each of the laser units is one of the following: 100 GHz, 200 GHz, 400 GHz, 800 GHz, and above 800 GHz.

5. The laser according to claim 1, characterized in that A light field adjustment layer composed of InGaAsP is embedded in the buffer layer. The light field adjustment layer has at least one layer, and the thickness of each layer is 50 to 300 nm.

6. The laser according to claim 1, characterized in that The quantum well active layer is composed of InGaAsP or AlGaInAs, the gain spectrum of the quantum well active layer covers the wavelength range of the laser, and the number of alternations between quantum wells and barrier layers in the quantum well active layer is less than or equal to 3.

7. The laser according to claim 1, characterized in that The substrate is an n-type InP substrate; the n-pole of each laser unit is a common electrode, and the p-pole is controlled separately.

8. A method for preparing a multi-wavelength array laser, characterized in that: The method comprises: Prepare a substrate, and deposit a primary epitaxial layer on the substrate, wherein the primary epitaxial layer includes, from bottom to top, a buffer layer, a lower confinement layer, a quantum well active layer, an upper confinement layer, and a grating layer, wherein the thickness of the lower confinement layer is greater than that of the upper confinement layer; A grating region layer is prepared on the primary epitaxy using a high-order phase-shift grating or a high-order pitch-adjusted grating; the grating region layer includes a plurality of grating units, each of the grating units having a different grating period; Depositing a secondary epitaxial layer on the grating region layer, wherein the secondary epitaxial layer includes a waveguide layer and an ohmic contact layer from bottom to top; performing waveguide etching on the secondary epitaxial layer using a back-end process, and depositing an insulating layer on the outer side of the secondary epitaxial layer; A window is opened in the insulating layer, and a metal electrode is prepared at the position of the window.

9. The method according to claim 8, characterized in that The waveguide etching adopts ridge waveguide etching; the material of the insulating layer is silicon dioxide; The metal electrodes include an n-type electrode and a p-type electrode, wherein the n-type electrode is formed by electron beam evaporation and magnetron sputtering, and the p-type electrode is formed by electron beam evaporation and electroplating. After the metal electrode is prepared, it is annealed at 300-500° C. for 2-10 minutes to form an ohmic contact layer between the metal electrode layer and the waveguide layer.

10. The method according to claim 9, characterized in that The isolation paths between the p-type electrodes of the laser units are prepared by photolithography.

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