Laterally buried grating DFB laser and preparation method thereof

Abstract

The invention provides a laterally buried grating DFB laser and a preparation method thereof, through stacked arrangement of an N-type contact layer, an N-type limiting layer, an active layer, a P-type limiting layer and a P-type contact layer, lateral gratings are buried at two sides of a ridge waveguide and are close to the active layer, and by using a transverse coupling mechanism of the lateral gratings and an active layer light field, the lateral optical field of the N-type contact layer and the P-type limiting layer is formed. The grating coupling coefficient mainly depends on the lateral distance instead of the etching depth, so that the sensitivity of the device performance to the etching depth is reduced, and the performance stability of the laser is remarkably improved. Meanwhile, an additional etching stop layer does not need to be introduced in the preparation process of the structure, the epitaxial growth and etching process is simplified, the manufacturing cost is reduced, lattice mismatch, interface defects and additional light absorption loss caused by the etching stop layer are avoided, and the light output efficiency and long-term reliability of the laser can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor laser technology, and in particular to a side-buried grating DFB laser and its fabrication method. Background Technology

[0002] DFB lasers typically employ gratings etched onto the active waveguide to achieve single-mode operation through coupling between the optical field and the grating. The coupling strength of the grating is characterized by the coupling coefficient κ, which is determined by the grating's refractive index modulation depth, periodicity, and the degree of overlap with the optical field mode. The etching depth of the grating directly determines the modulation amplitude of the waveguide refractive index, and the coupling coefficient κ is directly proportional to this modulation amplitude. Since the coupling coefficient is a key parameter affecting the laser's single-mode performance, threshold current, and output power, nanoscale grating structures are extremely sensitive to the κ value. Even small deviations in etching depth can cause significant changes in the κ value, deviating from the design value and resulting in unstable spectral characteristics. In current buried grating DFB laser manufacturing processes, an etching stop layer is often incorporated into the waveguide structure to precisely control the grating etching depth.

[0003] However, in some material system architectures, such as GaAs-based quantum wells and quantum dot lasers, and silicon-based quantum dot lasers, fabricating an etch stop layer increases the complexity of the epitaxial process. Introducing a stop layer during epitaxy or deposition requires additional growth or deposition steps and imposes strict requirements on material thickness and uniformity, increasing manufacturing difficulty and cost. Summary of the Invention

[0004] This invention provides a side-buried grating DFB laser and its fabrication method, which solves the problem that the fabrication of the etching stop layer in the prior art increases the fabrication complexity and cost.

[0005] This invention provides a laterally buried grating DFB laser, comprising: N-type contact layer; An N-type confinement layer is disposed on the N-type contact layer; An active layer is disposed on the N-type confinement layer; A P-type confinement layer is disposed on the active layer. The P-type confinement layer includes an unetched P-type confinement layer, a ridge waveguide, and a lateral grating. The ridge waveguide is disposed on the unetched P-type confinement layer, and the lateral grating is buried on both sides of the ridge waveguide and close to the active layer. A P-type contact layer is disposed on the ridge waveguide.

[0006] According to the present invention, a lateral buried grating DFB laser is provided, wherein the lateral width of the lateral grating from the ridge waveguide is 0~2. .

[0007] According to the present invention, a side-buried grating DFB laser is provided, wherein the thickness of the unetched P-type confinement layer ranges from 0 to 300 nm.

[0008] According to the present invention, a side-buried grating DFB laser is provided, wherein the width of the ridge waveguide is in the range of 2~10. .

[0009] According to the present invention, a lateral buried grating DFB laser is provided, wherein the lateral grating satisfies the Bragg condition and has a periodicity. Calculate using the following formula: ; in, This indicates the grating order of the lateral grating; This represents the Bragg wavelength of the lateral grating; This represents the effective refractive index of the ridge waveguide.

[0010] According to the present invention, a lateral buried grating DFB laser is provided, wherein the width of the unetched grating region in the lateral grating accounts for a proportion of the period ranging from 30% to 70%.

[0011] According to the present invention, a lateral buried grating DFB laser is provided, wherein the lateral grating and the ridge waveguide are made of the same material.

[0012] This invention also provides a method for fabricating a laterally buried grating DFB laser, comprising: An N-type contact layer, an N-type confinement layer, and an active layer are sequentially grown on the substrate; An unetched P-type confinement layer is grown on the active layer; A P-type confinement layer and a P-type contact layer are sequentially grown on the unetched P-type confinement layer; The P-type contact layer and the P-type confinement layer are etched to construct a ridge waveguide and expose the unetched P-type confinement layer. Lateral gratings are fabricated on the unetched P-type confinement layers exposed on both sides of the ridge waveguide, such that the lateral gratings are buried on both sides of the ridge waveguide and close to the active layer; The unetched P-type confinement layer, the ridge waveguide, and the lateral grating together constitute the P-type confinement layer.

[0013] According to a method for fabricating a lateral buried grating DFB laser provided by the present invention, the lateral width of the lateral grating from the ridge waveguide is 0~2. .

[0014] According to the method for fabricating a lateral buried grating DFB laser provided by the present invention, the thickness of the unetched P-type confinement layer ranges from 0 to 300 nm.

[0015] The laterally buried grating DFB laser and its fabrication method provided by this invention utilize a stacked configuration of an N-type contact layer, an N-type confinement layer, an active layer, a P-type confinement layer, and a P-type contact layer. The lateral grating is buried on both sides of the ridge waveguide and close to the active layer. By leveraging the lateral coupling mechanism between the lateral grating and the active layer's optical field, the grating coupling coefficient primarily depends on the lateral distance rather than the etching depth, thereby reducing the device's performance sensitivity to etching depth and significantly improving the laser's performance stability. Furthermore, this structure eliminates the need for an additional etch stop layer during fabrication, simplifying epitaxial growth and etching processes, reducing manufacturing costs, and avoiding lattice mismatch, interface defects, and additional optical absorption losses introduced by the etch stop layer. This effectively improves the laser's optical output efficiency and long-term reliability. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of the lateral buried grating DFB laser provided by the present invention; Figure 2 This is a top view schematic diagram of the lateral buried grating DFB laser provided by the present invention; Figure 3 This is a schematic diagram of the main structure of the lateral buried grating DFB laser provided by the present invention; Figure 4 This is a schematic flowchart of the fabrication method of the lateral buried grating DFB laser provided by the present invention.

[0018] Figure label: 1: N-type contact layer; 2: N-type confinement layer; 3: active layer; 4: P-type confinement layer; 41: ridge waveguide; 42: unetched P-type confinement layer; 43: lateral grating; 5: P-type contact layer. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0020] The development of the DFB semiconductor laser was a technological innovation responding to the urgent need for dynamic single-mode light sources in optical communication. By designing a Bragg grating inside the laser, it achieved wavelength selectivity and stability, thus overcoming the limitations imposed on communication systems by fiber dispersion. It has not only driven a revolution in global communication networks but has also become an indispensable key component in modern precision measurement and sensing technologies.

[0021] It should be noted that in current buried grating DFB laser processes, an etch stop layer is often incorporated into the waveguide structure to precisely control the grating etching depth. However, in some material structure architectures, such as quantum wells and quantum dot lasers epitaxially mounted on GaAs substrates, and silicon-based quantum dot lasers, fabricating an etch stop layer increases the complexity of the epitaxial process. Introducing a stop layer during epitaxy or deposition requires additional growth or deposition steps and imposes strict requirements on material thickness and uniformity, increasing manufacturing difficulty and cost.

[0022] To address the aforementioned issues, this invention provides a side-buried grating DFB laser to simplify the epitaxial growth and etching process of the laser, thereby achieving low-cost and stable laser fabrication. Figure 1 This is a schematic diagram of the structure of the lateral buried grating DFB laser provided by the present invention, as shown below. Figure 1 As shown, the laser includes: N-type contact layer 1; An N-type limiting layer 2 is disposed on the N-type contact layer 1; Active layer 3 is disposed on the N-type confinement layer 2; A P-type confinement layer 4 is disposed on the active layer 3. The P-type confinement layer includes a ridge waveguide 41, an unetched P-type confinement layer 42, and a lateral grating 43. The ridge waveguide 41 is disposed on the unetched P-type confinement layer 42, and the lateral grating 43 is buried on both sides of the ridge waveguide 41 and close to the active layer 3. A P-type contact layer 5 is disposed on the ridge waveguide 41.

[0023] Specifically, the N-type contact layer 1 is located at the bottom layer of the device, serving as a substrate or basic contact layer for epitaxial growth. It is mainly used to provide carrier injection channels and the basis for subsequent electrode fabrication.

[0024] An N-type confinement layer 2 is disposed on top of the N-type contact layer 1. This layer typically has a lower refractive index than the active layer 3, and is used to confine the light field, prevent the light field from leaking towards the substrate, and at the same time work with the N-type contact layer to complete the electron transport and injection.

[0025] The active layer 3 is disposed above the N-type confinement layer 2. It should be noted that the active layer 3 is the core region for generating optical gain in the laser, where electron-hole recombination occurs under the influence of the injected current, thereby generating stimulated emission. Understandably, the active layer 3 can be configured using a quantum well structure or a quantum dot structure, depending on the actual lasing wavelength requirements.

[0026] The P-type confinement layer 4 is disposed above the active layer 3. It should be noted that, unlike traditional planar or simple ridge waveguide structures, the P-type confinement layer 4 in this embodiment is a composite structure, specifically including an unetched P-type confinement layer 42, a ridge waveguide 41, and a lateral grating 43. The ridge waveguide corresponds to... Figure 1 The raised part in the middle.

[0027] The specific structural positional relationship of the P-type confinement layer is as follows: First, the unetched P-type confinement layer 42 is located above the active layer 3. As the base layer of the entire P-type region, it covers the surface of the active layer 3 and plays a role in protecting the active layer and providing initial light confinement.

[0028] Secondly, a ridge waveguide 41 is disposed on the unetched P-type confinement layer 42, forming a raised ridge structure. Here, the main function of the ridge waveguide is to achieve transverse optical field confinement and current confinement, ensuring that the laser operates in the fundamental transverse mode.

[0029] Furthermore, the lateral grating 43 is buried on both sides of the ridge waveguide 41 and is located close to the active layer 3. Figure 2 This is a top view schematic diagram of the lateral buried grating DFB laser provided by the present invention, as shown in the figure. Figure 2 As shown, the ridge waveguide 41 is disposed on the unetched P-type confinement layer 42, and the lateral grating 43 is buried on both sides of the ridge waveguide 41.

[0030] It should be noted that "lateral" in "lateral grating" means that the grating structure is not located directly above or below the waveguide as in a traditional DFB laser, but rather distributed on the sides of the ridge waveguide. The lateral grating 43 being buried on both sides of the ridge waveguide 41 means that the grating structure is formed within the P-type confinement layer material and is encased by the surrounding medium. Therefore, based on this special geometric design, the grating can couple with the optical field in the active layer 3 via evanescent waves, thereby providing optical feedback through the Bragg diffraction effect and achieving selection and locking of specific wavelengths.

[0031] Finally, a P-type contact layer 5 is disposed on the ridge waveguide 41 to form a good ohmic contact with the external metal electrode and realize hole injection.

[0032] Figure 3 This is a schematic diagram of the main structure of the lateral buried grating DFB laser provided by the present invention, as shown in the figure. Figure 3 As shown, the laser includes: an N-type contact layer 1; an N-type confinement layer 2 disposed on the N-type contact layer 1; an active layer 3 disposed on the N-type confinement layer 2; a P-type confinement layer 4 disposed on the active layer 3, the P-type confinement layer including a ridge waveguide 41, an unetched P-type confinement layer 42 and a lateral grating 43; the ridge waveguide 41 is disposed on the unetched P-type confinement layer 42, the lateral grating 43 is buried on both sides of the ridge waveguide 41 and close to the active layer 3; and a P-type contact layer 5 disposed on the ridge waveguide 41.

[0033] It should be noted that by burying the lateral grating on both sides of the ridge waveguide, this lateral burial structure ensures that the overlap integral between the grating and the optical field is primarily determined by the lateral distance, rather than solely by the etching depth. Therefore, the structure provided in this embodiment makes the coupling coefficient insensitive to changes in etching depth. In other words, even with some deviation in etching depth during manufacturing, the grating's reflection characteristics and wavelength selectivity remain highly stable, thereby significantly improving the laser's performance stability.

[0034] Furthermore, since the grating is located on both sides of the ridge waveguide, it can be formed during fabrication by controlling the etching time or depth, eliminating the need for pre-epitaxial growth of a dedicated etch stop layer in the waveguide structure. This simplifies the epitaxial growth and etching process, reducing manufacturing costs. It also avoids lattice mismatch, interface defects, and resulting optical losses that might arise from introducing a heterogeneous etch stop layer, ensuring high device performance and reliability.

[0035] The laser provided in this invention employs a stacked configuration of an N-type contact layer, an N-type confinement layer, an active layer, a P-type confinement layer, and a P-type contact layer. A lateral grating is buried on both sides of the ridge waveguide and close to the active layer. Utilizing the lateral coupling mechanism between the lateral grating and the active layer's optical field, the grating coupling coefficient primarily depends on the lateral distance rather than the etching depth, thereby reducing the device's performance sensitivity to etching depth and significantly improving the laser's performance stability. Furthermore, this structure eliminates the need for an additional etch stop layer during fabrication, simplifying epitaxial growth and etching processes, reducing manufacturing costs, and avoiding lattice mismatch, interface defects, and additional optical absorption losses introduced by the etch stop layer. This effectively enhances the laser's optical output efficiency and long-term reliability.

[0036] Based on any of the above embodiments, the lateral width of the lateral grating from the ridge waveguide is 0~2. .

[0037] Specifically, such as Figure 2 As shown, the lateral width d of the lateral grating from the ridge waveguide is 0~2. The lateral gratings here can be symmetrically arranged relative to the ridge waveguide. It should be noted that the lateral width can reduce mode perturbation and loss while ensuring the coupling effect between the optical field and the grating, and taking into account the feasibility of manufacturing process and structural stability.

[0038] Based on any of the above embodiments, the thickness of the unetched P-type confinement layer ranges from 0 to 300 nm.

[0039] Here, the thickness of the unetched P-type confinement layer refers to the distance from the upper surface of the active layer along the epitaxial growth direction, i.e., vertically upwards, to the plane containing the bottom of the ridge waveguide. In other words, this thickness represents the residual thickness of the P-type confinement layer after it has been etched during the formation of the ridge waveguide. It should be noted that since the lateral gratings of this invention are disposed on both sides of the ridge waveguide, this thickness actually determines the vertical spacing between the bottom of the lateral gratings and the active layer.

[0040] It should also be noted that the appropriately retained unetched P-type confinement layer can play a role in current spread and current injection uniformity, improving the electrical performance of the device. At the same time, it provides a certain degree of isolation in the structure, reducing the impact of grating processing defects on the active region.

[0041] Based on any of the above embodiments, the width of the ridge waveguide ranges from 2 to 10. .

[0042] It should be noted that the width is limited to 2~10. This approach avoids both the excessive resistance and significantly increased manufacturing complexity caused by overly narrow waveguides, and the uneven current distribution and excessively high threshold current caused by overly wide waveguides. Consequently, it improves mode stability and ensures that the optical field is primarily concentrated in the active region to achieve high coupling efficiency.

[0043] Based on any of the above embodiments, the lateral grating satisfies the Bragg condition, and the period... Calculate using the following formula: ; in, This indicates the grating order of the lateral grating; This represents the Bragg wavelength of the lateral grating; This represents the effective refractive index of the ridge waveguide.

[0044] To meet the processing precision requirements of standard photolithography processes and reduce manufacturing costs, in this embodiment, the grating order is preferably an integer greater than or equal to 3, such as a third-order grating. In this case, the period of the lateral grating is on the order of micrometers or submicrometers, e.g., 0.6. -1.0 This allows the lateral grating to be formed directly in one step using ordinary photolithography, without the need for expensive electron beam lithography or holographic lithography.

[0045] It should be noted that the Bragg wavelength of the lateral grating here can be customized according to actual needs to meet the size range required by ordinary standard photolithography processes.

[0046] Based on any of the above embodiments, the width of the unetched grating region in the lateral grating accounts for a proportion of the period ranging from 30% to 70%.

[0047] Here, the duty cycle of the lateral buried grating, i.e., the width of the unetched grating region as a percentage of the period Λ, is 30% to 70%, which can effectively maintain the continuity of the optical field distribution in the waveguide core region, while reducing the scattering loss and mode distortion caused by etching, so that the grating can still produce a stable and strong feedback effect under the lateral structure.

[0048] Based on any of the above embodiments, the lateral grating and the ridge waveguide are made of the same material.

[0049] Based on any of the above embodiments Figure 4 The present invention provides a method for fabricating a side-buried grating DFB laser, which simplifies the epitaxial growth and etching process of the laser and achieves low-cost and stable laser fabrication. Figure 4 This is a schematic flowchart of the fabrication method of the side-buried grating DFB laser provided by the present invention, as shown below. Figure 4 As shown, the method includes: Step 410: An N-type contact layer, an N-type confinement layer, and an active layer are sequentially grown on the substrate.

[0050] Specifically, firstly, on a clean semiconductor substrate, such as a GaAs substrate, an N-type contact layer, an N-type confinement layer, and an active layer are grown sequentially from bottom to top using an epitaxial growth apparatus, according to the designed doping concentration and thickness. The active layer can be a multi-quantum-well structure, designed to provide optical gain at a specific wavelength.

[0051] Step 420: An unetched P-type confinement layer is grown on the active layer.

[0052] Specifically, a layer of P-type doped semiconductor material is epitaxially grown on the upper surface of the active layer, which is the unetched P-type confinement layer. It should be noted that the thickness of the layer grown in this step needs to be precisely controlled, for example, within the range of 0~300nm, because the thickness of the unetched P-type confinement layer will directly determine the vertical distance between the subsequently formed lateral grating and the active layer.

[0053] Step 430: A P-type confinement layer and a P-type contact layer are sequentially grown on the unetched P-type confinement layer.

[0054] Specifically, after step S2 is completed, without interrupting the growth or performing secondary growth after cleaning, the remaining P-type confinement layer material and the highly doped P-type contact layer continue to grow on top of the unetched P-type confinement layer.

[0055] Step 440: Etch the P-type contact layer and the P-type confinement layer to construct a ridge waveguide and expose the unetched P-type confinement layer.

[0056] Specifically, firstly, photoresist can be coated on the surface of the P-type contact layer 5, and the ridge waveguide pattern can be defined by photolithography, with the width controllable between 2 and 10 μm. Then, the P-type contact layer and part of the P-type confinement layer are etched from top to bottom using dry or wet etching techniques.

[0057] It should be noted that controlling the etching depth is crucial in this step. Etching needs to stop on the upper surface of the unetched P-type confinement layer 42 in step S2, thereby forming a stepped structure with a central bulge and flat sides. Since this application adopts a lateral grating design, the etching accuracy requirements in the vertical direction are relatively relaxed. Therefore, it is not necessary to pre-epitaxially grow a special heteromaterial etching stop layer between steps S2 and S3. This can be achieved simply by controlling the etching rate and time, thus avoiding the introduction of lattice mismatch and interface defects.

[0058] Step 450: A lateral grating is fabricated on the unetched P-type confinement layer exposed on both sides of the ridge waveguide, such that the lateral grating is buried on both sides of the ridge waveguide and close to the active layer; wherein the unetched P-type confinement layer, the ridge waveguide and the lateral grating together constitute the P-type confinement layer.

[0059] Specifically, after the ridge waveguide is formed, a grating is fabricated on the flat areas exposed on both sides of the ridge waveguide, i.e., the surface of the unetched P-type confinement layer 42. The specific operations include: recoating photoresist and defining the photoresist pattern of the grating using a photolithography process. It should be noted that embodiments of the present invention can employ a high-order grating design with a larger grating period, thus allowing direct exposure using a low-cost conventional contact or stepper lithography machine without the need for expensive electron beam direct writing. Subsequently, a periodic groove structure can be formed in the unetched P-type confinement layer through an etching process, thereby constructing a lateral grating.

[0060] At this point, the lateral grating, the ridge waveguide retained in step S4, and the unetched P-type confinement layer 42 grown in step S2 together constitute the complete P-type confinement layer. The lateral grating is located on the flank of the ridge waveguide in space and is buried in the P-type confinement layer material system, and is adjacent to the active layer through an extremely thin unetched layer.

[0061] In one embodiment, a quantum dot side-buried grating laser on a GaAs substrate is taken as an example. The active region of this device is InAs / GaAs quantum dot material, and its fabrication process and method include: First, an epitaxial growth is performed. That is, on an N-type GaAs substrate, molecular beam epitaxy is used to sequentially epitaxially grow: an N-type buffer layer, an N-type GaAs layer with a thickness of approximately 100–300 nm; an N-type confinement layer: an N-type AlGaAs layer with a thickness of approximately 1500 nm; and an active layer: several layers of InAs / GaAs self-assembled quantum dot structures are grown.

[0062] Next, the fabrication of the lateral buried grating is performed. The relevant parameters of the lateral grating can be set, including period, duty cycle, and depth. Then, electron beam lithography and dry etching techniques, such as inductively coupled plasma (ICP), can be used to fabricate the grating.

[0063] Next, a second epitaxial growth is performed. Specifically, the following layers are epitaxially grown sequentially using molecular beam epitaxy or metal-organic chemical vapor deposition: a P-type confinement layer (P-type AlGaAs or P-type GaInP layer, approximately 1300–1500 nm thick) and a P-type contact layer (P-type GaAs layer, approximately 300 nm thick). Finally, the laterally buried grating structure is completely planarized and buried.

[0064] Next, the ridge waveguide and electrode fabrication are performed. Specifically, the ridge waveguide is etched onto the flat surface after secondary epitaxy using photolithography and dry or wet etching. A SiO2 insulating layer is then deposited, and a window is created at the top of the ridge waveguide to expose the P-type contact layer. Finally, P-side electrodes are fabricated on the front side of the laser, using Ti / Pt / Au and other metallic materials.

[0065] Next, the N-side substrate of the epitaxial wafer is thinned using a grinding machine, typically to 150 micrometers, followed by a polishing process to 120 micrometers, and then cleaning.

[0066] Next, an N-side electrode is fabricated on the back side of the substrate, which can be made using AuGe / Ni / Au and other metal materials. Then, a rapid annealing process is performed using a rapid annealing device to ensure that the epitaxial wafer and the metal material form a good ohmic contact.

[0067] Finally, the wafers are diced into individual cores, which are then sintered and welded together, and finally encapsulated on a socket to complete the fabrication of the DFB laser.

[0068] The method provided in this invention utilizes a stacked configuration of an N-type contact layer, an N-type confinement layer, an active layer, a P-type confinement layer, and a P-type contact layer. A lateral grating is buried on both sides of the ridge waveguide and close to the active layer. By leveraging the lateral coupling mechanism between the lateral grating and the active layer's optical field, the grating coupling coefficient primarily depends on the lateral distance rather than the etching depth. This reduces the device's performance sensitivity to etching depth and significantly improves the laser's performance stability. Furthermore, this structure eliminates the need for an additional etch stop layer during fabrication, simplifying epitaxial growth and etching processes, reducing manufacturing costs, and avoiding lattice mismatch, interface defects, and additional optical absorption losses introduced by the etch stop layer. This effectively enhances the laser's optical output efficiency and long-term reliability.

[0069] Based on any of the above embodiments, the lateral width of the lateral grating from the ridge waveguide is 0~2μm.

[0070] Based on any of the above embodiments, the thickness of the unetched P-type confinement layer ranges from 0 to 300 nm.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laterally buried grating DFB laser, characterized in that, include: N-type contact layer; An N-type confinement layer is disposed on the N-type contact layer; An active layer is disposed on the N-type confinement layer; A P-type confinement layer is disposed on the active layer. The P-type confinement layer includes an unetched P-type confinement layer, a ridge waveguide, and a lateral grating. The ridge waveguide is disposed on the unetched P-type confinement layer, and the lateral grating is buried on both sides of the ridge waveguide and close to the active layer. A P-type contact layer is disposed on the ridge waveguide.

2. The lateral buried grating DFB laser according to claim 1, characterized in that, The lateral width of the lateral grating from the ridge waveguide is 0~2. .

3. The lateral buried grating DFB laser according to claim 1, characterized in that, The thickness of the unetched P-type confinement layer ranges from 0 to 300 nm.

4. The lateral buried grating DFB laser according to any one of claims 1 to 3, characterized in that, The width of the ridge waveguide ranges from 2 to 10. .

5. The lateral buried grating DFB laser according to any one of claims 1 to 3, characterized in that, The lateral grating satisfies the Bragg condition, and its period is... Calculate using the following formula: ； in, This indicates the grating order of the lateral grating; This represents the Bragg wavelength of the lateral grating; This represents the effective refractive index of the ridge waveguide.

6. The lateral buried grating DFB laser according to claim 5, characterized in that, The width of the unetched grating region in the lateral grating accounts for a proportion of the period ranging from 30% to 70%.

7. The lateral buried grating DFB laser according to any one of claims 1 to 3, characterized in that, The lateral grating and the ridge waveguide are made of the same material.

8. A method for fabricating a laterally buried grating DFB laser, characterized in that, include: An N-type contact layer, an N-type confinement layer, and an active layer are sequentially grown on the substrate; An unetched P-type confinement layer is grown on the active layer; A P-type confinement layer and a P-type contact layer are sequentially grown on the unetched P-type confinement layer; The P-type contact layer and the P-type confinement layer are etched to construct a ridge waveguide and expose the unetched P-type confinement layer. Lateral gratings are fabricated on the unetched P-type confinement layers exposed on both sides of the ridge waveguide, such that the lateral gratings are buried on both sides of the ridge waveguide and close to the active layer; The unetched P-type confinement layer, the ridge waveguide, and the lateral grating together constitute the P-type confinement layer.

9. The method for fabricating a laterally buried grating DFB laser according to claim 8, characterized in that, The lateral width of the lateral grating from the ridge waveguide is 0~2. .

10. The method for fabricating a laterally buried grating DFB laser according to claim 8, characterized in that, The thickness of the unetched P-type confinement layer ranges from 0 to 300 nm.

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