A vertical cavity surface emitting laser and a method of manufacturing the same

Abstract

The application discloses a vertical cavity surface emitting laser and a manufacturing method thereof. The vertical cavity surface emitting laser comprises a substrate, a lower Bragg reflection layer, an active layer, an oxidation layer, an upper Bragg reflection layer and a relief grating layer which are sequentially stacked. The oxidation layer comprises an oxidation aperture. A vertical projection of the oxidation aperture on the substrate is in the same shape as a vertical projection of a mesa on the substrate. The edges of the vertical projection of the oxidation aperture on the substrate are parallel to the edges of the vertical projection of the mesa on the substrate. The relief grating layer comprises a relief grating structure and a relief layer surrounding the relief grating structure. The relief grating structure is located at a light outlet of the mesa. The relief grating structure comprises a plurality of spaced-apart grating strips. The relief layer is used for suppressing the lasing of high-order modes. The vertical cavity surface emitting laser and the manufacturing method thereof can make the vertical cavity surface emitting laser emit single-mode and single-polarization laser.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic device technology, and in particular to a vertical cavity surface-emitting laser and its fabrication method. Background Technology

[0002] Vertical cavity surface-emitting lasers (VCSELs) are widely used in optical communication, 3D printing, lidar, integrated microchip systems and other fields due to their miniaturization, low power loss, fast modulation response and continuous beam output.

[0003] However, existing vertical-cavity surface-emitting lasers have many limitations, such as polarization instability and the emission of light in multiple modes. These limitations further restrict the application of vertical-cavity surface-emitting lasers. Summary of the Invention

[0004] This invention provides a vertical cavity surface-emitting laser and its fabrication method, which enables the vertical cavity surface-emitting laser to emit single-mode, single-polarized laser light.

[0005] According to one aspect of the present invention, a vertical cavity surface-emitting laser is provided, the vertical cavity surface-emitting laser comprising: a substrate, a lower Bragg reflector layer, an active layer, an oxide layer, an upper Bragg reflector layer and an embossed grating layer stacked sequentially;

[0006] The upper Bragg reflector layer, the oxide layer, the active layer, and at least a portion of the lower Bragg reflector layer constitute a platform;

[0007] The oxide layer includes oxide pores;

[0008] The shape of the vertical projection of the oxide pores on the substrate is the same as the shape of the vertical projection of the mesa on the substrate;

[0009] The maximum dimension of the vertical projection of the mesa onto the substrate in the first direction is greater than the maximum dimension of the vertical projection of the mesa onto the substrate in the second direction, wherein the first direction is perpendicular to the second direction; each side of the vertical projection of the oxide aperture onto the substrate is parallel to each side of the vertical projection of the mesa onto the substrate.

[0010] The embossed grating layer includes an embossed grating structure and an embossed layer that surrounds and is seamlessly adjacent to the embossed grating structure;

[0011] The relief grating structure is located at the light outlet of the platform; the relief grating structure includes multiple spaced grating strips; the relief layer is used to suppress the lasing of higher-order modes.

[0012] Optionally, the vertical projection of the oxide aperture on the substrate overlaps the vertical projection of the relief grating structure on the substrate.

[0013] Optionally, the center of the vertical projection of the embossed grating structure onto the substrate coincides with the center of the vertical projection of the oxide aperture onto the substrate.

[0014] Optionally, the shape of the vertical projection of the platform onto the substrate is an axisymmetric figure containing orthogonal axes of symmetry;

[0015] The axis of symmetry of the axisymmetric pattern is parallel to a specific crystal orientation;

[0016] The shape of the vertical projection of the platform onto the substrate includes racetrack shape, ellipse, rhombus or rectangle.

[0017] Optionally, the outer contour of the vertical projection of the embossed grating structure onto the substrate is elliptical.

[0018] The axis of symmetry of the vertical projection of the relief grating structure onto the substrate coincides with the axis of symmetry of the vertical projection of the mesa onto the substrate.

[0019] Optionally, the vertical-cavity surface-emitting laser provided in this embodiment further includes two first electrodes;

[0020] The two first electrodes are located on the surface of the relief grating layer away from the substrate;

[0021] The line connecting the centers of the vertical projections of the two first electrodes on the substrate is parallel or perpendicular to the major axis of the outer contour of the vertical projection of the relief grating structure on the substrate.

[0022] Optionally, the maximum size of the oxide pores is 7 μm to 8 μm.

[0023] Optionally, the thickness of the relief grating structure is equal to the thickness of the relief layer;

[0024] The material of the relief grating structure is the same as the material of the relief layer;

[0025] The material of the relief grating structure includes GaAs;

[0026] The thickness of the relief grating structure is one-quarter of the lasing wavelength.

[0027] Optionally, the vertical-cavity surface-emitting laser provided in this embodiment further includes a second electrode;

[0028] The second electrode is located on the surface of the substrate;

[0029] The second electrode and the mesa are located on the same side of the substrate.

[0030] According to another aspect of the present invention, a method for fabricating a vertical-cavity surface-emitting laser is provided, the method comprising:

[0031] Provide a substrate;

[0032] A lower Bragg reflector layer, an active layer, an oxide layer, an upper Bragg reflector layer, and an embossed grating layer are sequentially formed on one side of the substrate; wherein the upper Bragg reflector layer, the oxide layer, the active layer, and at least a portion of the lower Bragg reflector layer constitute a mesa; the oxide layer includes oxide apertures; the shape of the vertical projection of the oxide apertures onto the substrate is the same as the shape of the vertical projection of the mesa onto the substrate; the maximum size of the vertical projection of the mesa onto the substrate in a first direction is greater than the maximum size of the vertical projection of the mesa onto the substrate in a second direction, wherein the first direction is perpendicular to the second direction; each side of the vertical projection of the oxide apertures onto the substrate is correspondingly parallel to each side of the vertical projection of the mesa onto the substrate; the embossed grating layer includes an embossed grating structure and an embossed layer surrounding and seamlessly adjacent to the embossed grating structure; the embossed grating structure is located at the light exit port of the mesa; the embossed grating structure includes multiple spaced grating strips; the embossed layer is used to suppress the lasing of higher-order modes.

[0033] This embodiment provides a vertical-cavity surface-emitting laser (VCSEL) in which the mesa and the oxide aperture have the same shape when projected vertically onto the substrate. The maximum size of the mesa's vertical projection on the substrate in a first direction is larger than its maximum size in a second direction. This configuration allows the mesa and the oxide aperture to control the mode and polarization of light at different locations. Light at locations with larger oxide aperture sizes is emitted with essentially unrestricted mode and polarization, while light at locations with smaller oxide aperture sizes is suppressed. The sides of the mesa's vertical projection on the substrate are parallel to the sides of the oxide aperture's vertical projection on the substrate, ensuring that the control of light mode and polarization by the mesa is identical to that by the oxide aperture. The laser also includes an embossed grating structure and an embossed layer. The embossed grating structure is located at the exit port of the mesa, the embossed layer suppresses the lasing of higher-order modes, and the embossed grating structure can transmit the fundamental mode. Furthermore, the embossed grating structure has polarization selectivity characteristics, ultimately enabling the VCSEL provided in this embodiment to emit single-mode, single-polarization laser light.

[0034] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of a vertical cavity surface-emitting laser according to an embodiment of the present invention;

[0037] Figure 2 This is a diagram showing the positional relationship between an embossed grating structure, oxide aperture, and the vertical projection of the mesa onto a substrate, according to an embodiment of the present invention.

[0038] Figures 3-6 This is a diagram showing the positional relationship between an embossed grating structure, oxide aperture, and the vertical projection of the mesa onto the substrate, according to an embodiment of the present invention.

[0039] Figure 7 This is a top view schematic diagram of a vertical cavity surface-emitting laser provided according to an embodiment of the present invention;

[0040] Figure 8 This is a top view schematic diagram of another vertical cavity surface-emitting laser provided according to an embodiment of the present invention;

[0041] Figure 9 This is a schematic diagram of another vertical cavity surface-emitting laser provided according to an embodiment of the present invention;

[0042] Figure 10 This is a schematic flowchart of a method for fabricating a vertical cavity surface-emitting laser according to an embodiment of the present invention;

[0043] Figures 11-18 This is a schematic diagram of the process structure for fabricating a vertical cavity surface-emitting laser, provided as an embodiment of the present invention. Detailed Implementation

[0044] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0045] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0046] Figure 1 This is a schematic diagram of a vertical cavity surface-emitting laser according to an embodiment of the present invention. (Refer to...) Figure 1 The vertical-cavity surface-emitting laser provided in this embodiment includes: a substrate 110, a lower Bragg reflector layer 120, an active layer 130, an oxide layer 140, an upper Bragg reflector layer 150, and an embossed grating layer 160, which are stacked sequentially. The upper Bragg reflector layer 150, the oxide layer 140, the active layer 130, and at least a portion of the lower Bragg reflector layer 120 constitute a mesa 200. The oxide layer 140 includes an oxide aperture 141. The shape of the vertical projection of the oxide aperture 141 onto the substrate 110 is the same as the shape of the vertical projection of the mesa 200 onto the substrate 110. The vertical projection of the mesa 200 onto the substrate 110 is firstly... The maximum dimension in the Y direction is greater than the maximum dimension in the second direction X of the vertical projection of the mesa 200 on the substrate 110, wherein the first direction Y is perpendicular to the second direction X; each side of the vertical projection of the oxide aperture 141 on the substrate 110 is parallel to each side of the vertical projection of the mesa 200 on the substrate 110; the relief grating layer 160 includes a relief grating structure 161 and a relief layer 162 that surrounds and is seamlessly adjacent to the relief grating structure 161; the relief grating structure 161 is located at the light outlet of the mesa 200; the relief grating structure 161 includes multiple spaced grating strips; the relief layer 162 is used to suppress the lasing of higher-order modes.

[0047] Specifically, the tabletop 200 may include a partial thickness of the lower Bragg reflector layer 120, or it may include the entire lower Bragg reflector layer 120. Figure 1The structure shown is a mesa 200 including a full-length lower Bragg reflector layer 120. The upper Bragg reflector layer 150 is composed of alternating layers of high refractive index with an odd number of quarter-laser wavelength thicknesses and low refractive index layers with an odd number of quarter-laser wavelength thicknesses. The lower Bragg reflector layer 120 is also composed of alternating layers of high refractive index with an odd number of quarter-laser wavelength thicknesses and low refractive index layers with an odd number of quarter-laser wavelength thicknesses. The materials of the upper Bragg reflector layer 150 and the lower Bragg reflector layer 120 can be III-V group semiconductor materials, such as arsenides, phosphides, nitrides, etc. The thickness of the active layer 130 is an integer multiple of half the laser wavelength.

[0048] The sides of the vertical projection of the oxide aperture 141 onto the substrate 110 are parallel to the sides of the vertical projection of the mesa 200 onto the substrate 110. That is, the orientation of the oxide aperture 141 is consistent with the orientation of the mesa 200. For example, if both the vertical projections of the oxide aperture 141 and the mesa 200 onto the substrate 110 are elliptical, then the major axis of the vertical projection of the mesa 200 onto the substrate 110 covers the major axis of the vertical projection of the oxide aperture 141 onto the substrate 110. Setting the orientation of the oxide aperture 141 to be consistent with the orientation of the mesa 200 allows the selection of light modes and polarization by the mesa 200 and the oxide aperture 141 to be consistent.

[0049] The maximum size of the vertical projection of the mesa 200 onto the substrate 110 in the first direction Y is greater than its maximum size in the second direction X. This arrangement allows for different amounts of light emitted from different regions of the mesa 200 and the oxide aperture 141, thereby enabling control over the polarization and mode of the light. For example... Figure 2 This is a diagram showing the positional relationship between an embossed grating structure, oxide aperture, and the vertical projection of the mesa onto a substrate, according to an embodiment of the present invention. Figure 2 The vertical projections of the oxide aperture 141 and the mesa 200 onto the substrate 110 are both elliptical. The light pattern and polarization along the major axis (first direction Y) of the ellipse are largely unrestricted, while the light pattern and polarization along the minor axis (second direction X) are mostly suppressed. Therefore, by setting the maximum size of the oxide aperture 141 in the first direction Y and the maximum size in the second direction X to be different, control over the light pattern and polarization can be achieved.

[0050] The outer contour of the vertical projection of the relief grating structure 161 onto the substrate 110 can be circular or elliptical. The relief grating structure 161 includes multiple grating strips, with through-holes between the strips. The width of each grating strip can be 300 nm, and the spacing between adjacent strips can be 300 nm. When the relief grating structure 161 is located at the light exit port of the mesa 200, light emitted from the mesa 200 can exit through the relief grating structure 161. The relief grating structure 161 has polarization properties, ensuring that the emitted light is linearly polarized. The relief layer 162 has the function of suppressing the lasing of higher-order modes. Specifically, the relief layer 161 can be a λ / 4 thick reverse GaAs layer, where λ is the lasing wavelength. The λ / 4 thick reverse GaAs layer can increase the threshold condition for the lasing of higher-order modes, preventing them from reaching the lasing threshold in the relief layer 162 and thus suppressing them. In summary, the higher-order modes in the light emitted from the mesa 200 are suppressed by the relief layer 162, while the fundamental mode in the light emitted from the mesa 200 can be emitted through the relief grating structure 161. Since the relief grating structure 161 has polarization properties, the vertical cavity surface-emitting laser provided in this embodiment can ultimately emit a single-mode, single-polarization laser.

[0051] This embodiment provides a vertical-cavity surface-emitting laser (VCSEL) in which the mesa and the oxide aperture have the same shape when projected vertically onto the substrate. The maximum size of the mesa's vertical projection on the substrate in a first direction is larger than its maximum size in a second direction. This configuration allows the mesa and the oxide aperture to control the mode and polarization of light at different locations. Light at locations with larger oxide aperture sizes is emitted with essentially unrestricted mode and polarization, while light at locations with smaller oxide aperture sizes is suppressed. The sides of the mesa's vertical projection on the substrate are parallel to the sides of the oxide aperture's vertical projection on the substrate, ensuring that the control of light mode and polarization by the mesa is identical to that by the oxide aperture. The laser also includes an embossed grating structure and an embossed layer. The embossed grating structure is located at the exit port of the mesa, the embossed layer suppresses the lasing of higher-order modes, and the embossed grating structure can transmit the fundamental mode. Furthermore, the embossed grating structure has polarization selectivity characteristics, ultimately enabling the VCSEL provided in this embodiment to emit single-mode, single-polarization laser light.

[0052] Optional, continue to refer to Figure 2 The vertical projection of the oxide aperture 141 on the substrate 110 covers the vertical projection of the relief grating structure 161 on the substrate 110.

[0053] Specifically, the size of the oxide aperture 141 provided in this embodiment is larger than the size of the relief grating structure 161. The larger oxide aperture 141 can reduce the resistance of the vertical-cavity surface-emitting laser and improve its reliability. Therefore, the vertical-cavity surface-emitting laser provided in this embodiment can emit single-mode, single-polarization laser while also reducing resistance and improving reliability. Furthermore, when the relief grating structure 161 is smaller, the size of the relief layer 162 will increase, thereby increasing the suppression of more higher-order modes by the relief layer 162 and improving the purity of the single-mode emitted by the relief grating structure 161.

[0054] Optionally, the center of the vertical projection of the relief grating structure onto the substrate coincides with the center of the vertical projection of the oxide aperture onto the substrate.

[0055] Specifically, the center of the vertical projection of the relief grating structure onto the substrate coincides with the center of the vertical projection of the mesa onto the substrate. The coincidence of the center of the vertical projection of the relief grating structure onto the substrate and the center of the vertical projection of the oxide aperture onto the substrate allows the center of the light emitted from the mesa to pass through the center of the relief grating structure. This enables the vertical cavity surface-emitting laser provided in this embodiment to emit a complete fundamental mode, and the energy distribution of points equidistant from the center of the formed light spot is also substantially equal.

[0056] Optional, Figures 3-6 This is a diagram showing the positional relationship between the relief grating structure, oxide aperture, and vertical projection of the mesa onto the substrate, according to an embodiment of the present invention. Figures 3-6 The shape of the vertical projection of mesa 200 onto substrate 110 is an axisymmetric figure containing orthogonal symmetry axes, the symmetry axes of which are parallel to a specific crystal orientation; the shape of the vertical projection of mesa 200 onto substrate 110 includes a racetrack shape (see reference). Figure 3 ), oval (reference) Figure 4 ), rhombus (reference) Figure 5 ) or rectangle (reference) Figure 6 ).

[0057] Specifically, the axially symmetric platform 200 and oxide aperture 141 are easy to manufacture. Racetrack-shaped, elliptical, rhomboid, and rectangular platforms 200 and oxide aperture 141 are easy to manufacture and offer better selection of light modes and polarization.

[0058] Optional, continue to refer to Figures 3-6 The outer contour of the vertical projection of the relief grating structure 161 onto the substrate 110 is elliptical; the axis of symmetry of the vertical projection of the relief grating structure 161 onto the substrate 120 coincides with the axis of symmetry of the vertical projection of the mesa 200 onto the substrate 110.

[0059] Specifically, setting the outer contour of the embossed grating structure 161 to be elliptical allows for further control over the polarization and mode of light. The major axis of the outer contour of the embossed grating structure 161 is aligned with the arrangement direction of the grating strips. When the vertical projection of the mesa 200 onto the substrate is racetrack-shaped, the major axis of the outer contour of the embossed grating structure 161 is parallel to the longer side of the racetrack shape. When the vertical projection of the mesa 200 onto the substrate is elliptical, the major axis of the outer contour of the embossed grating structure 161 is parallel to the major axis of the vertical projection of the mesa 200 onto the substrate. When the vertical projection of the mesa 200 onto the substrate is rhomboid, the major axis of the outer contour of the embossed grating structure 161 is parallel to the longer diagonal of the vertical projection of the mesa 200 onto the substrate. When the vertical projection of the mesa 200 onto the substrate is rectangular, the major axis of the outer contour of the embossed grating structure 161 is parallel to the longer side of the vertical projection of the mesa 200 onto the substrate.

[0060] Optional, Figure 7 This is a top view schematic diagram of a vertical cavity surface-emitting laser according to an embodiment of the present invention. Figure 8 This is a top view schematic diagram of another vertical-cavity surface-emitting laser provided according to an embodiment of the present invention, with reference to... Figure 7 and Figure 8 The vertical cavity surface-emitting laser provided in this embodiment also includes two first electrodes 170; the two first electrodes 170 are located on the surface of the relief grating layer away from the substrate; the line connecting the centers of the vertical projections of the two first electrodes 170 on the substrate is parallel or perpendicular to the long axis of the outer contour of the vertical projection of the relief grating structure 161 on the substrate 110.

[0061] Specifically, the first electrode is also a P-type electrode, and the two first electrodes 170 are spaced apart, which allows current to be injected into some positions of the mesa 200 while not injecting current into others, ultimately resulting in different currents at different positions of the mesa 200. The line connecting the centers of the vertical projections of the two first electrodes 170 onto the substrate 110 is parallel or perpendicular to the major axis of the outer contour of the vertical projection of the relief grating structure 161 onto the substrate 110, which can further enhance the polarization characteristics.

[0062] Optionally, the maximum size of the oxide pores is 7 μm to 8 μm.

[0063] Specifically, an oxide aperture with a maximum size of 7μm to 8μm can reduce the resistance of a vertical-cavity surface-emitting laser (VCSEL) and improve its reliability.

[0064] Optionally, the thickness of the relief grating structure is equal to the thickness of the relief layer; the material of the relief grating structure is equal to the material of the relief layer; the material of the relief grating structure includes GaAs; and the thickness of the relief grating structure is one-quarter of the lasing wavelength.

[0065] Specifically, setting the material of the relief layer to GaAs and its thickness to one-quarter of the lasing wavelength can improve the suppression characteristics of the relief layer for higher-order modes.

[0066] Optional, Figure 9 This is a schematic diagram of another vertical-cavity surface-emitting laser provided according to an embodiment of the present invention, with reference to... Figure 9 The vertical cavity surface-emitting laser provided in this embodiment also includes a second electrode 180; the second electrode 180 is located on the surface of the substrate 110; the second electrode 180 and the mesa 200 are located on the same side of the substrate 110.

[0067] Specifically, the second electrode 180 is also an N-type electrode. The first electrode 170 and the second electrode 180 can form a current loop, enabling the vertical cavity surface-emitting laser to operate normally when powered on.

[0068] Figure 10 This is a schematic flowchart illustrating a method for fabricating a vertical-cavity surface-emitting laser according to an embodiment of the present invention. (Refer to...) Figure 10 The vertical-cavity surface-emitting laser provided in this embodiment includes the following fabrication steps:

[0069] S110, Provide a substrate.

[0070] S120. A lower Bragg reflector layer, an active layer, an oxide layer, an upper Bragg reflector layer, and an embossed grating layer are sequentially formed on one side of a substrate; wherein, the upper Bragg reflector layer, the oxide layer, the active layer, and at least a portion of the lower Bragg reflector layer constitute a mesa; the oxide layer includes oxide apertures; the shape of the vertical projection of the oxide apertures onto the substrate is the same as the shape of the vertical projection of the mesa onto the substrate; the maximum dimension of the vertical projection of the mesa onto the substrate in a first direction is greater than the maximum dimension of the vertical projection of the mesa onto the substrate in a second direction, wherein the first direction is perpendicular to the second direction; each side of the vertical projection of the oxide apertures onto the substrate is correspondingly parallel to each side of the vertical projection of the mesa onto the substrate; the embossed grating layer includes an embossed grating structure and an embossed layer surrounding and seamlessly adjacent to the embossed grating structure; the embossed grating structure is located at the light outlet of the mesa; the embossed grating structure includes multiple spaced grating strips; the embossed layer is used to suppress the lasing of higher-order modes.

[0071] The following section details another method for fabricating a vertical-cavity surface-emitting laser. Figures 11-18 This is a schematic diagram of the process structure for fabricating a vertical-cavity surface-emitting laser according to an embodiment of the present invention, with reference to... Figures 11-18 The manufacturing method includes the following steps:

[0072] S210, Provide an epitaxial wafer.

[0073] For details, please refer to Figure 11The epitaxial wafer 300 includes a substrate 110, a lower Bragg reflector layer 120, an active layer 130 and an upper Bragg reflector layer 150 stacked sequentially.

[0074] S220. An embossed grating transition layer is grown on one surface of the epitaxial wafer.

[0075] For details, please refer to Figure 12 , Figure 12 A schematic diagram of the structure for forming the relief grating transition layer 163.

[0076] S230. An embossed grating layer is formed by photolithography etching, wherein the embossed grating layer includes an embossed grating structure and an embossed layer.

[0077] For details, please refer to Figure 13 , Figure 13 To form a structural schematic diagram of the relief grating layer 160, the relief layer 162 in the relief grating layer 160 surrounds the relief grating structure 161 and is seamlessly adjacent to the relief grating structure 161.

[0078] S240. A first passivation layer is formed on the surface of the relief grating layer away from the epitaxial wafer.

[0079] For details, please refer to Figure 14 , Figure 14 A schematic diagram of the structure for forming the first passivation layer 190.

[0080] S250, forming the first groove.

[0081] For details, please refer to Figure 15 The first groove 191 can be formed by etching the first passivation layer 190, the relief layer 162, the upper Bragg reflector layer 150, the active layer 130, and part of the lower Bragg reflector layer 120. The outline of the first groove 191 is racetrack-shaped, elliptical, rhomboid, or rectangular.

[0082] S260, Form an oxide layer, wherein the oxide layer includes oxide pores.

[0083] For details, please refer to Figure 16 Oxide is injected into the upward Bragg reflective layer 150 within the first groove 191, thereby forming an oxide layer 140. The oxide layer 140 includes oxide apertures 141. The vertical projection of the oxide apertures 141 onto the substrate 110 is racetrack-shaped, elliptical, rhomboid, or rectangular. After the oxide layer 140 is formed, a mesa is also formed.

[0084] S270, A second passivation layer is formed in the first groove.

[0085] For details, please refer to Figure 17 , Figure 17 A schematic diagram of the structure for forming the second passivation layer 191.

[0086] S280, the first electrode and the second electrode are formed sequentially.

[0087] For details, please refer to Figure 18 , Figure 18 This is a schematic diagram of the structure forming the first electrode 170 and the second electrode 180.

[0088] S290, A third passivation layer is formed, which covers the first electrode and the second electrode.

[0089] Specifically, the third passivation layer is used to protect the first and second electrodes from damage.

[0090] S291. Thin the substrate.

[0091] Specifically, thinning the substrate can reduce the size of a vertical cavity surface-emitting laser.

[0092] S292. A metal layer is formed on the side of the substrate away from the lower Bragg reflector layer.

[0093] Specifically, the metal layer can serve as a support, and the formed metal layer can also improve heat dissipation when the vertical cavity surface-emitting laser is working.

[0094] The fabrication method of the vertical cavity surface-emitting laser provided in this embodiment has the same beneficial effects as the vertical cavity surface-emitting laser provided in any embodiment of the present invention. For technical details not detailed in this embodiment, please refer to the vertical cavity surface-emitting laser provided in any embodiment of the present invention.

[0095] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0096] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A vertical-cavity surface-emitting laser, characterized in that, include: The substrate, lower Bragg reflector layer, active layer, oxide layer, upper Bragg reflector layer and relief grating layer are stacked in sequence. The upper Bragg reflector layer, the oxide layer, the active layer, and at least a portion of the lower Bragg reflector layer constitute a platform; The oxide layer includes oxide pores; The shape of the vertical projection of the oxide pores on the substrate is the same as the shape of the vertical projection of the mesa on the substrate; The maximum size of the vertical projection of the mesa onto the substrate in a first direction is greater than the maximum size of the vertical projection of the mesa onto the substrate in a second direction, wherein the first direction is perpendicular to the second direction; Each side of the vertical projection of the oxide pore size onto the substrate corresponds to and is parallel to each side of the vertical projection of the mesa onto the substrate. The embossed grating layer includes an embossed grating structure and an embossed layer that surrounds and is seamlessly adjacent to the embossed grating structure; The relief grating structure is located at the light outlet of the platform; the relief grating structure includes multiple spaced grating strips; the relief layer is used to suppress the lasing of higher-order modes; It also includes two first electrodes; the two first electrodes are located on the surface of the relief grating layer away from the substrate; the line connecting the centers of the vertical projections of the two first electrodes on the substrate is parallel or perpendicular to the major axis of the outer contour of the vertical projection of the relief grating structure on the substrate; The two first electrodes are spaced apart on the relief grating layer so that current is injected into some parts of the platform and not injected into others.

2. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The vertical projection of the oxide aperture on the substrate overlaps the vertical projection of the relief grating structure on the substrate.

3. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The center of the vertical projection of the embossed grating structure onto the substrate coincides with the center of the vertical projection of the oxide aperture onto the substrate.

4. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The shape of the vertical projection of the platform onto the substrate is an axisymmetric figure containing orthogonal axes of symmetry; The axis of symmetry of the axisymmetric pattern is parallel to a specific crystal orientation; The shape of the vertical projection of the platform onto the substrate includes racetrack shape, ellipse, rhombus or rectangle.

5. The vertical-cavity surface-emitting laser according to claim 4, characterized in that, The outer contour of the relief grating structure projected vertically onto the substrate is elliptical. The axis of symmetry of the vertical projection of the relief grating structure onto the substrate coincides with the axis of symmetry of the vertical projection of the mesa onto the substrate.

6. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The maximum size of the oxide pores is 7μm~8μm.

7. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The thickness of the relief grating structure is equal to the thickness of the relief layer; The material of the relief grating structure is the same as the material of the relief layer; The material of the relief grating structure includes GaAs; The thickness of the relief grating structure is one-quarter of the lasing wavelength.

8. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, It also includes a second electrode; The second electrode is located on the surface of the substrate; The second electrode and the mesa are located on the same side of the substrate.

9. A method for fabricating a vertical-cavity surface-emitting laser, used to prepare a vertical-cavity surface-emitting laser according to any one of claims 1-8, characterized in that, include: Provide a substrate; A lower Bragg reflector layer, an active layer, an oxide layer, an upper Bragg reflector layer, and an embossed grating layer are sequentially formed on one side of the substrate; wherein the upper Bragg reflector layer, the oxide layer, the active layer, and at least a portion of the lower Bragg reflector layer constitute a mesa; the oxide layer includes oxide apertures; the shape of the vertical projection of the oxide apertures onto the substrate is the same as the shape of the vertical projection of the mesa onto the substrate; the maximum size of the vertical projection of the mesa onto the substrate in a first direction is greater than the maximum size of the vertical projection of the mesa onto the substrate in a second direction, wherein the first direction is perpendicular to the second direction; each side of the vertical projection of the oxide apertures onto the substrate is correspondingly parallel to each side of the vertical projection of the mesa onto the substrate; the embossed grating layer includes an embossed grating structure and an embossed layer surrounding and seamlessly adjacent to the embossed grating structure; the embossed grating structure is located at the light exit port of the mesa; the embossed grating structure includes multiple spaced grating strips; the embossed layer is used to suppress the lasing of higher-order modes.

Images