Vertical cavity surface emitting laser

Abstract

A vertical cavity surface emitting laser disclosed by the present invention comprises a substrate and an epitaxial structure arranged on a first surface of the substrate, the epitaxial structure comprises a first DBR layer, at least two groups of alternately formed active layers and oxide layers and a second DBR layer which are sequentially stacked from bottom to top, and a light emitting hole is arranged above the epitaxial structure. An area below the position of the light outlet hole comprises a resonance light-emitting area and a side mode suppression area located around the resonance light-emitting area, and the substrate located in the resonance light-emitting area and the surface of each epitaxial layer in the epitaxial structure are parallel to each other and are perpendicular to the light outlet direction. The structure in the side mode suppression region comprises an inclined structure which is obliquely arranged relative to the same epitaxial layer of the resonance light-emitting region, the inclined structure at least comprises at least two groups of active layers, oxide layers and second DBR layers which are alternately formed, and the oxidation tail ends of all the oxide layers are located in the side mode suppression region. And the influence caused by misalignment of the oxide layer is avoided.

Description

Technical Field

[0001] The invention relates to the field of lasers, and in particular to a vertical cavity surface emitting laser. Background Art

[0002] Vertical Cavity Surface Emitting Laser (VCSEL) or multi-junction VCSEL has the specification requirement of small divergence angle. The current chip process can perform surface relief (Surface Relief-SR) or optical window dielectric film relief (Emitters Nitride-EN) process to limit high-order transverse modes, thereby modifying the light shape and reducing the divergence angle.

[0003] refer to Figure 1 The SR process etches directly on the epitaxial layer, so that the thickness of the etched area and the unetched area respectively play the role of high reflection and low reflection. This process destroys the epitaxial structure of the light-emitting area, and the etching depth and uniformity are difficult to control, the process is difficult, and the yield is low.

[0004] refer to Figure 2 The EN process is to first deposit a layer of optical film and then align it for etching, so as to define the high-reflection area and low-reflection area of ​​the light-emitting position. This process requires precise deposition of the optical film. If the film thickness is too thin in subsequent tests, it needs to be lengthened, or too thick, it needs to be thinned. This will destroy the ideal step edge during the first etching and reduce the ability to subsequently limit the high-order modes of the device.

[0005] The process surface improvement of the SR process or EN process does not involve changing the epitaxial structure. For the epitaxial structure with multiple oxide layers, the edges of each oxide layer are prone to misalignment. Even if the depth, thickness and width of the SR process or EN process fully meet the requirements, unavoidable high-order modes will occur. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a vertical cavity surface emitting laser.

[0007] In order to achieve the above purpose, the technical solution of the present invention is:

[0008] A vertical cavity surface emitting laser comprises a substrate and an epitaxial structure arranged on a first surface of the substrate, wherein the epitaxial structure comprises a first DBR layer, at least two groups of alternately formed active layers and oxide layers, and a second DBR layer stacked in sequence from bottom to top, a first electrode is arranged on the second surface of the substrate, a second electrode is arranged on the second DBR layer, a light exit hole is arranged above the epitaxial structure, the lower region where the light exit hole is located comprises a resonant light emitting region and a side mode suppression region located around the resonant light emitting region, the surfaces of the substrate and each epitaxial layer in the epitaxial structure located in the resonant light emitting region are parallel to each other and perpendicular to the light emitting direction, the structure in the side mode suppression region comprises an inclined structure arranged obliquely relative to the same epitaxial layer in the resonant light emitting region, the inclined structure comprises at least the at least two groups of alternately formed active layers and oxide layers, and the second DBR layer, and the oxidation ends of all oxide layers are located in the side mode suppression region.

[0009] Preferably, the first surface of the substrate located in the side mode suppression zone is tilted relative to the first surface of the substrate located in the resonant light-emitting zone, so that the epitaxial structure above the substrate in the side mode suppression zone is tilted at the same angle in the light emitting direction relative to the epitaxial structure above the substrate in the resonant light-emitting zone.

[0010] Preferably, the thickness of the substrate is 400-800 μm, and the height difference formed by the inclination of the first surface of the substrate located in the side mode suppression area is 3-5 μm.

[0011] Preferably, the first surface of the substrate located in the side mode suppression zone and the first surface of the substrate located in the resonant light-emitting zone are in the same plane, and the upper surface of the first DBR layer located in the side mode suppression zone is inclined relative to the upper surface of the first DBR layer located in the resonant light-emitting zone, so that at least two groups of alternating active layers and oxide layers and the second DBR layer above the first DBR layer in the side mode suppression zone are respectively inclined at the same angle in the light emitting direction relative to the at least two groups of alternating active layers and oxide layers and the second DBR layer in the resonant light-emitting zone.

[0012] Preferably, the thickness of the first DBR layer is 4-8 μm, and the height difference formed by the inclination of the upper surface of the first DBR layer located in the side mode suppression area is 3-5 μm.

[0013] Preferably, the acute angle formed by each epitaxial layer of the inclined structure relative to the plane where the same epitaxial layer of the resonant light-emitting region is located is in the range of 45° to 75°.

[0014] Preferably, the oxidized ends of all the oxidized layers located in the side mode suppression region have different projection positions on the plane where the first surface of the substrate located in the resonant light emitting region is located.

[0015] Preferably, each epitaxial layer in the inclined structure is inclined downward or upward relative to the corresponding epitaxial layer in the resonant light emitting region.

[0016] Preferably, the oxidized end of the oxide layer in the side mode suppression zone gradually approaches the resonant light-emitting zone at a projection position on a plane where the first surface of the substrate located in the resonant light-emitting zone is located from top to bottom, or the oxidized end of the oxide layer in the side mode suppression zone gradually moves away from the resonant light-emitting zone at a projection position on a plane where the first surface of the substrate located in the resonant light-emitting zone is located from top to bottom.

[0017] Preferably, when the second DBR layer is a P-DBR layer and the second electrode is a P-type electrode, a dielectric layer is provided above the P-DBR layer, and the dielectric layer covers the area on the P-DBR layer except the P-type electrode.

[0018] Preferably, the thickness of the dielectric layer in the resonant light-emitting region is smaller than the thickness of the dielectric layer in the side mode suppression region.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The vertical cavity surface emitting laser proposed in the present invention includes a resonant light emitting zone and a side mode suppression zone within a range set at the light emitting position. At least two groups of alternating active layers and oxide layers and a second DBR layer in the side mode suppression zone are tilted relative to the same epitaxial layer of the resonant light emitting zone, resulting in thickness distortion, so that the high-order modes of the side mode suppression zone are suppressed, the resonant light emitting zone emits light normally, and the side mode suppression zone does not emit light, thereby being able to modify the light type and reduce the divergence angle.

[0021] (2) In the vertical cavity surface emitting laser proposed by the present invention, the oxidized ends of all the oxide layers in the side mode suppression region can have different projection positions on the plane where the first surface of the substrate located in the resonant light emitting region is located, thereby avoiding the influence caused by the misalignment of the oxidized ends of the oxide layers.

[0022] (3) The vertical cavity surface emitting laser proposed in the present invention can further reduce the difficulty of growing the epitaxial layer by patterning the substrate to distort the thickness of the epitaxial layer located in the side mode suppression region, or patterning the first DBR layer, and can further modify the light type by combining with the EN process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of a prior art SR process;

[0024] Figure 2 is a schematic diagram of an EN process in the prior art;

[0025] Figure 3 This is a schematic structural diagram of a vertical cavity surface emitting laser according to the first embodiment of the present application;

[0026] Figure 4 A schematic diagram of a current path of a vertical cavity surface emitting laser according to the first embodiment of the present application;

[0027] Figure 5 A schematic diagram of a composite carrier light-emitting region of a vertical cavity surface emitting laser according to the first embodiment of the present application;

[0028] Figure 6-10 A schematic diagram of the manufacturing process of the vertical cavity surface emitting laser of the first embodiment of the present application;

[0029] Fig.11 This is a schematic structural diagram of a vertical cavity surface emitting laser according to the second embodiment of the present application;

[0030] Fig.12 This is a schematic structural diagram of a vertical cavity surface emitting laser according to Embodiment 3 of the present application;

[0031] Fig.13 This is a schematic structural diagram of a vertical cavity surface emitting laser according to a fourth embodiment of the present application;

[0032] Fig.14 The structure of the vertical cavity surface emitting laser of the fifth embodiment of the present application is shown in FIG. Figure 1 ;

[0033] Fig.15 The structure of the vertical cavity surface emitting laser of the fifth embodiment of the present application is shown in FIG. Figure 2 ;

[0034] Fig.16 This is a schematic structural diagram of a vertical cavity surface emitting laser according to Comparative Example 1 of the present application;

[0035] Fig.17 This is a schematic structural diagram of a vertical cavity surface emitting laser according to comparative example 2 of the present application;

[0036] Fig.18 A comparison diagram of light patterns of the vertical cavity surface emitting lasers of Example 1 and Comparative Example 1 of the present application;

[0037] Fig.19 This is a light pattern diagram of a vertical cavity surface emitting laser of comparative example 2 of the present application;

[0038] Reference numerals: 1, substrate; 2, first DBR layer; 3, active layer; 4, oxide layer; 5, second DBR layer; 6, second electrode; 7, dielectric layer; 8, first electrode. DETAILED DESCRIPTION

[0039] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. The various drawings of the present invention are only for illustration to make it easier to understand the present invention, and the specific proportions can be adjusted according to design requirements. The upper and lower relationships of the relative elements and the definitions of the front / back in the figures described in the text should be understood by those skilled in the art to refer to the relative positions of the components, so they can all be flipped to present the same components, which should all fall within the scope disclosed in this specification.

[0040] Embodiment 1

[0041] refer to Figure 3 The embodiment of the present application proposes a vertical cavity surface emitting laser, comprising a substrate 1 and an epitaxial structure arranged on the first surface of the substrate 1, wherein the epitaxial structure comprises a first DBR layer 2, at least two groups of active layers 3 and oxide layers 4 formed alternately, and a second DBR layer 5 stacked in sequence from bottom to top. The embodiment of the present application is described by taking the first DBR layer 2 as an N-DBR layer and the second DBR layer 5 as a P-DBR layer as an example. A first electrode 8 is arranged on the second surface of the substrate 1, and a second electrode 6 is arranged on the P-DBR layer. In the embodiment of the present application, the first electrode 8 is an N-type electrode, and the second electrode 6 is a P-type electrode. A dielectric layer 7 is arranged above the P-DBR layer, and the dielectric layer 7 covers the area on the P-DBR layer except the P-type electrode. In one embodiment, the dielectric layer 7 can be made of SiN or other materials, and the thickness is set to (2n+1) / 4 times or (2n) / 4 times the light emission wavelength, and n can be 1, 2, 3 or 4, etc., to ensure that the vertical cavity surface emitting laser has a good light emission effect. The thickness of the epitaxial structure is 8 to 14 μm. In a preferred embodiment, the thickness of the epitaxial structure is 10 μm. The epitaxial structure on the first surface of the substrate 1 uses multiple active layers 3, and each active layer 3 is provided with an oxide layer 4 correspondingly. The oxide layer 4 includes an unoxidized area and an oxidized insulating area located around the unoxidized area. The boundary between the oxidized insulating area and the unoxidized area is the oxidized end. The multiple active layers 3 are powered by the P-type electrode and the N-type electrode, and the current path is limited by the oxidized insulating area of ​​each oxide layer 4, so that the corresponding active layer 3 under each oxide layer 4 emits light.

[0042] Furthermore, a light exit hole is provided above the epitaxial structure, and the aperture of the light exit hole is larger than the maximum diameter of all unoxidized areas, that is, the projection range of all unoxidized areas on the plane where the first surface of the substrate 1 located in the resonant light-emitting area A1 is located is located within the projection range of the light exit hole on the plane where the first surface of the substrate 1 located in the resonant light-emitting area A1 is located. The light exit hole can be surrounded by a P-type electrode or other epitaxial layers, and is not limited here. The lower area where the light-emitting hole is located includes a resonant light-emitting area A1 and a side mode suppression area A2 located around the resonant light-emitting area A1. The surfaces of the substrate 1 located in the resonant light-emitting area A1 and each epitaxial layer in the epitaxial structure are parallel to each other and perpendicular to the light-emitting direction. The structure in the side mode suppression area A2 includes an inclined structure that is inclined relative to the same epitaxial layer in the resonant light-emitting area A1. The inclined structure includes at least two groups of alternating active layers 3 and oxide layers 4 and a P-DBR layer, and the oxidized ends of all oxide layers 4 are located in the side mode suppression area A2. The oxidized ends of all oxide layers 4 located in the side mode suppression area A2 have different projection positions on the plane where the first surface of the substrate 1 located in the resonant light-emitting area A1 is located. The side mode suppression area A2 can suppress high-order modes and avoid the influence caused by the misalignment of the oxide layer 4. The epitaxial structure in the resonant light-emitting region A1 is the same as the light-emitting region structure of a standard VCSEL, and the thickness of the P-DBR layer and the dielectric layer 7 meet the light field resonance conditions, so it can emit light normally. The range of the resonant light-emitting region A1 can be selected according to the process technology capability, electrical requirements and epitaxial material requirements. In one embodiment, the width or diameter of the resonant light-emitting region A1 can be 8 to 18 μm. However, due to the presence of the inclined structure in the side mode suppression region A2, some epitaxial structures produce thickness distortion during epitaxial growth, resulting in the mismatch between the resonant wavelength of the side mode suppression region A2 and the light-emitting wavelength, so the side mode suppression region A2 does not emit light. Due to the presence of the resonant light-emitting region A1 and the side mode suppression region A2, the high-order modes of at least two groups of composite carrier light-emitting regions are suppressed, thereby modifying the light type and reducing the divergence angle. At the same time, because the side mode suppression region A2 has a certain width, it can provide stop positions of the oxide layer 4 with different oxidation rates, thereby forming oxidation ends at different positions, avoiding the influence of the inconsistent oxidation rate of the oxide layer 4.

[0043] In a specific embodiment, the first surface of the substrate 1 located in the side mode suppression area A2 is tilted relative to the first surface of the substrate 1 located in the resonance light emitting area A1, so that the epitaxial structure above the substrate 1 in the side mode suppression area A2 is tilted at the same angle relative to the epitaxial structure above the substrate 1 in the resonance light emitting area A1 in the light emitting direction. Specifically, the first surface of the substrate 1 can be etched, that is, the first surface of the substrate 1 is patterned, so that the first surface of the substrate 1 located in the resonance light emitting area A1 is perpendicular to the light emitting direction, and the first surface of the substrate 1 located in the resonance light emitting area A1 extends obliquely to the surrounding to form the first surface of the substrate 1 located in the side mode suppression area A2. Specifically, the thickness of the substrate 1 is 400-800 μm, and the height difference formed by the tilt of the first surface of the substrate 1 located in the side mode suppression area A2 is 3-5 μm. In a preferred embodiment, the height difference is 4 μm. The acute angle between the first surface of the substrate 1 located in the side mode suppression area A2 and the plane where the first surface of the substrate 1 located in the resonance light emitting area A1 is located is 45°-75°. In a preferred embodiment, the acute angle is set to 60°. Epitaxial structures are formed by epitaxial growth in sequence on the first surface of the substrate 1 located in the resonant light-emitting region A1 and the first surface of the substrate 1 located in the side mode suppression region A2. The epitaxial structure epitaxially grown above the first surface of the substrate 1 in the side mode suppression region A2 is tilted relative to the same epitaxial layer of the epitaxial structure epitaxially grown above the first surface of the substrate 1 in the resonant light-emitting region A1. The surface of each epitaxial layer in the epitaxial structure located in the resonant light-emitting region A1 is also parallel to the first surface of the substrate 1 located in the resonant light-emitting region A1. Although the surfaces of each epitaxial layer in the epitaxial structure located in the side mode suppression region A2 are also parallel to each other, they are all tilted at the same angle relative to the same epitaxial layer in the epitaxial structure located in the resonant light-emitting region A1 in the light-emitting direction to form an inclined structure. The tilt angle of the inclined structure is determined by the tilt angle of the first surface of the substrate 1 in the side mode suppression region A2. Specifically, each epitaxial layer in the inclined structure tilts downward or upward relative to the corresponding epitaxial layer in the resonant light-emitting region A1. That is to say, each epitaxial layer in the inclined structure extends from the same epitaxial layer in the resonant light-emitting area A1 to the surrounding area and forms an upward tilt or a downward tilt. The acute angle of each epitaxial layer in the inclined structure relative to the plane where the same epitaxial layer in the resonant light-emitting area A1 is located is in the range of 45° to 75°, that is, no matter whether the inclined structure is tilted upward or downward, in the light-emitting direction, the acute angle of each epitaxial layer in the inclined structure and the plane where the same epitaxial layer in the resonant light-emitting area A1 is located is the same, and the range is 45° to 75°. It should be noted that each epitaxial layer located in the resonant light-emitting area A1 extends in the direction close to the second surface of the substrate 1 and is downward tilted, and each epitaxial layer located in the resonant light-emitting area A1 extends in the direction away from the second surface of the substrate 1 and is upward tilted.

[0044] Further, such as Figure 3 As shown, the embodiment of the present application takes the inclined structure in which each epitaxial layer is inclined downward relative to the corresponding epitaxial layer in the resonant light-emitting region A1, and has three groups of active layers 3 and oxide layers 4 as an example. The oxidation ends of the oxide layers 4 are inconsistent. In one case, the oxidation ends of the oxide layers 4 in the side mode suppression region A2 gradually move away from the resonant light-emitting region A1 from top to bottom in the projection position of the plane where the first surface of the substrate 1 located in the resonant light-emitting region A1 is located. That is, the diameter of the unoxidized area in the oxide layer 4 increases from top to bottom, so as to form the following: Figure 4 The current path is shown in Figure 2. Figure 5 As shown, the oxidized ends of all oxide layers 4 are located in the side mode suppression zone A2, and the unoxidized area surrounded by the oxidized ends of each oxide layer 4 forms a group of composite carrier light-emitting zones. Therefore, in the embodiment of the present application, there are three groups of composite carrier light-emitting zones B1, B2 and B3. The epitaxial structure of the side mode suppression zone A2 is tilted downward, resulting in thickness distortion, which leads to the suppression of high-order modes of the three groups of composite carrier light-emitting zones, thereby modifying the light type and reducing the divergence angle. Since it is difficult to keep the oxidation rates of different oxide layers 4 consistent due to the epitaxy and chip end processes, the diameters of the unoxidized areas of each oxide layer 4 are inconsistent. If the oxidation rates of each oxide layer 4 of a conventional device are inconsistent, different active layers 3 will produce different side mode effects, affecting the final light type and divergence angle. Each epitaxial layer in the inclined structure is tilted downward relative to the corresponding epitaxial layer in the resonant light emitting area A1, so a bevel range can be provided in the side mode suppression area A2. Even if the oxidation rates of each oxide layer 4 are inconsistent, as long as the oxidation end stops within the bevel range in the side mode suppression area A2, it will not affect the final light type. Because the thickness of the epitaxial layer at the bevel position is distorted, destroying the perfect resonance effect, the area cannot produce laser light, thereby not affecting the light output at the normal center position of the resonant light emitting area A1.

[0045] The embodiment of the present application also proposes a method for manufacturing a vertical cavity surface emitting laser, comprising the following steps:

[0046] (1)Reference Figure 6 and Figure 7 , providing a substrate 1 with a thickness of 400 to 800 μm, and etching the first surface of the substrate 1, so that the first surface of the substrate 1 in the resonant light emitting area A1 remains flat and perpendicular to the preset light emitting direction, and the first surface of the substrate 1 in the resonant light emitting area A1 is tilted downward and extends to form the first surface of the substrate 1 in the side mode suppression area A2, and the acute angle between the first surface of the substrate 1 in the side mode suppression area A2 and the plane where the first surface of the substrate 1 in the resonant light emitting area A1 is located is 45° to 75°;

[0047] (2)Reference Figure 8-10, epitaxially growing an N-DBR layer, at least two groups of alternating active layers 3 and oxide layers 4, and a P-DBR layer on the first surface of the substrate 1 obtained by etching in step (1), forming a P-type electrode on the surface of the P-DBR layer and defining a table surface, the oxide layer 4 is formed by performing an oxidation process on the epitaxial layer above the active layer 3, the oxidation speeds of the various oxide layers 4 are inconsistent, and therefore the oxidation depths are also inconsistent, the formed oxidized ends have different projection positions on the plane where the first surface of the substrate 1 located in the resonant light-emitting region A1 is located, but are all located in the side mode suppression region A2, in one case, the oxidized ends of the oxide layer 4 located in the side mode suppression region A2 gradually move away from the resonant light-emitting region A1 from top to bottom in the projection position on the plane where the first surface of the substrate 1 located in the resonant light-emitting region A1 is located;

[0048] (3)Reference Figure 3 The surface of the P-DBR layer except the P-type electrode is covered with a dielectric layer 7, and a P-type electrode metal and an N-type electrode are formed on the dielectric layer 7 and the second surface of the substrate 1 respectively.

[0049] Embodiment 2

[0050] refer to Fig.11 The difference between the second embodiment of the present application and the first embodiment is that: on the basis of the first embodiment, the EN process can be further used to etch the dielectric layer 7, so that the thickness of the dielectric layer 7 located in the resonant light-emitting area A1 is less than the thickness of the dielectric layer 7 located in the side mode suppression area A2, and the light type can be further modified. The depth of the thinning of the dielectric layer 7 located in the resonant light-emitting area A1 is (2m-1) / 4 times the wavelength of the light output, and m can be 1, 2, 3 or 4, etc., but (2m-1) / 4 is less than (2n+1) / 4 or (2n) / 4.

[0051] Embodiment 3

[0052] refer to Fig.12, the difference between the third embodiment of the present application and the first embodiment is that each epitaxial layer in the inclined structure is inclined upward relative to the corresponding epitaxial layer of the resonant light-emitting area A1. In this case, since the substrate corresponding to the resonant light-emitting area A1 is recessed relative to the substrate in the side mode suppression area A2, the etching area is small, and as long as a flat table is formed in the resonant light-emitting area A1, the overall uniformity requirement is not high, and the difficulty is relatively low. Similarly, taking three groups of active layers 3 and oxide layers 4 as an example, in one of the cases, the oxidized end of the oxide layer 4 located in the side mode suppression area A2 is gradually projected from top to bottom on the plane where the first surface of the substrate 1 located in the resonant light-emitting area A1 is located, and gradually approaches the resonant light-emitting area A1, that is, the diameter of the unoxidized area in the oxide layer 4 decreases from top to bottom. The oxidized ends of all oxide layers 4 are located in the side mode suppression area A2, and the epitaxial structure of the side mode suppression area A2 is tilted upward, resulting in thickness distortion, which leads to the suppression of the high-order modes of the three groups of composite carrier light-emitting areas, thereby modifying the light type and reducing the divergence angle.

[0053] Embodiment 4

[0054] refer to Fig.13 The difference between the fourth embodiment of the application and the third embodiment is that: on the basis of the third embodiment, the EN process can be further used to etch the dielectric layer 7, so that the thickness of the dielectric layer 7 located in the resonant light-emitting area A1 is smaller than the thickness of the dielectric layer 7 located in the side mode suppression area A2, and the light type can be further modified.

[0055] Embodiment 5

[0056] refer to Fig.14 The difference between the fifth embodiment of the application and the first embodiment is that the first surface of the substrate 1 located in the side mode suppression area A2 and the first surface of the substrate 1 located in the resonant light emitting area A1 are in the same plane, and the upper surface of the N-DBR layer located in the side mode suppression area A2 is tilted relative to the upper surface of the N-DBR layer located in the resonant light emitting area A1, so that at least two groups of alternating active layers 3 and oxide layers 4 and P-DBR layers above the N-DBR layer in the side mode suppression area A2 are tilted at the same angle relative to at least two groups of alternating active layers 3 and oxide layers 4 and P-DBR layers in the resonant light emitting area A1. Specifically, the thickness of the N-DBR layer is 4-8μm, and the height difference formed by the tilt of the upper surface of the N-DBR layer located in the side mode suppression area A2 is 3-5μm. Since the thickness of the N-DBR layer is relatively thick, it is difficult to grow the epitaxial structure after the substrate 1 is patterned. Therefore, it is possible to pattern the N-DBR layer after the N-DBR layer is epitaxially generated, and then grow at least two groups of alternating active layers 3 and oxide layers 4, P-DBR layers and dielectric layers 7 in sequence.

[0057] For further reference, Fig.15 On this basis, the dielectric layer 7 can also be etched using the EN process to make the thickness of the dielectric layer 7 in the resonant light emitting area A1 smaller than the thickness of the dielectric layer 7 in the side mode suppression area A2, thereby further modifying the light type.

[0058] Comparative Example 1

[0059] refer to Fig.16 , Comparative Example 1 of the present application proposes a vertical cavity surface emitting laser, including a substrate 1 and an epitaxial structure arranged on the first surface of the substrate 1, the epitaxial structure includes an N-DBR layer stacked from bottom to top, at least two groups of active layers 3 and oxide layers 4 formed alternately, and a P-DBR layer, an N-type electrode is arranged on the second surface of the substrate 1, a P-type electrode is arranged on the P-DBR layer, a dielectric layer 7 is arranged above the P-DBR layer, and the dielectric layer 7 covers the area on the P-DBR layer except the P-type electrode, and the surface of each epitaxial layer on the epitaxial structure is located in the same plane. Since the oxidation speed of the oxide layer is inconsistent during oxidation, there is a situation where the oxidation ends of each oxide layer are prone to misalignment.

[0060] Comparative Example 2

[0061] refer to Fig.17 The difference between the comparative example 2 and the comparative example 1 of the present application is that: based on the structure of the comparative example 1, the dielectric layer 7 can be further etched by the EN process, so that the thickness of the dielectric layer 7 located in the light output hole is further reduced, and the light type can be further modified.

[0062] like Fig.18 As shown, from the light type comparison results of the vertical cavity surface emitting laser of the first embodiment of the present application and the vertical cavity surface emitting laser of the first comparative example, it can be seen that the structure of the vertical cavity surface emitting laser proposed in the first embodiment of the present application can effectively improve the light type of the vertical cavity surface emitting laser, reduce the divergence angle, suppress the high-order modes in the side mode suppression zone, and reduce the process difficulty, avoiding the influence caused by the misalignment of the oxidation ends of each oxide layer. Fig.19 Even if the EN process of comparative example 2 of the present application is used to modify the light type, the vertical cavity surface emitting laser in comparative example 2 still has unavoidable high-order modes. It can be seen that the structure of the vertical cavity surface emitting laser proposed in the embodiment of the present application can effectively suppress the high-order modes in the side mode suppression zone, thereby achieving the effect of effectively modifying the light type.

[0063] In the embodiment of the present application, the first DBR layer 2 may also be a P-DBR layer, and the second DBR layer 5 may also be an N-DBR layer. The second electrode 6 is an N-type electrode, and the first electrode 8 is a P-type electrode. The specific structure is not repeated here.

[0064] The above embodiments are only used to further illustrate the technical solutions of the present invention, but the present invention is not limited to the embodiments. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention fall within the protection scope of the technical solutions of the present invention.

Claims

1. A vertical cavity surface emitting laser, characterized in that: The invention comprises a substrate and an epitaxial structure arranged on a first surface of the substrate, wherein the epitaxial structure comprises a first DBR layer, at least two groups of alternately formed active layers and oxide layers, and a second DBR layer stacked in sequence from bottom to top, a first electrode is arranged on the second surface of the substrate, a second electrode is arranged on the second DBR layer, a light exit hole is arranged above the epitaxial structure, the lower region where the light exit hole is located comprises a resonant light-emitting region and a side mode suppression region located around the resonant light-emitting region, the surfaces of the substrate and each epitaxial layer in the epitaxial structure located in the resonant light-emitting region are parallel to each other and perpendicular to the light exiting direction, the structure in the side mode suppression region comprises an inclined structure arranged obliquely relative to the same epitaxial layer in the resonant light-emitting region, the inclined structure comprises at least the at least two groups of alternately formed active layers and oxide layers, and the second DBR layer, and the oxidation ends of all oxide layers are located in the side mode suppression region.

2. The vertical cavity surface emitting laser according to claim 1, characterized in that: The first surface of the substrate located in the side mode suppression zone is tilted relative to the first surface of the substrate located in the resonant light-emitting zone, so that the epitaxial structure above the substrate in the side mode suppression zone is tilted at the same angle in the light emitting direction relative to the epitaxial structure above the substrate in the resonant light-emitting zone.

3. The vertical cavity surface emitting laser according to claim 2, characterized in that: The thickness of the substrate is 400-800 μm, and the height difference formed by the first surface of the substrate located in the side mode suppression area due to the inclination is 3-5 μm.

4. The vertical cavity surface emitting laser according to claim 1, characterized in that: The first surface of the substrate located in the side mode suppression area and the first surface of the substrate located in the resonant light-emitting area are in the same plane, and the upper surface of the first DBR layer located in the side mode suppression area is tilted relative to the upper surface of the first DBR layer located in the resonant light-emitting area, so that at least two groups of alternating active layers and oxide layers and the second DBR layer above the first DBR layer in the side mode suppression area are respectively tilted at the same angle in the light emitting direction relative to the at least two groups of alternating active layers and oxide layers and the second DBR layer in the resonant light-emitting area.

5. The vertical cavity surface emitting laser according to claim 4, characterized in that: The thickness of the first DBR layer is 4-8 μm, and the height difference formed by the inclination of the upper surface of the first DBR layer located in the side mode suppression area is 3-5 μm.

6. The vertical cavity surface emitting laser according to claim 1, characterized in that: The acute angle formed by each epitaxial layer of the inclined structure relative to the plane where the same epitaxial layer of the resonant light-emitting region is located is in the range of 45° to 75°.

7. The vertical cavity surface emitting laser according to claim 1, characterized in that: The oxidized ends of all the oxidized layers located in the side mode suppression region have different projection positions on the plane where the first surface of the substrate located in the resonant light emitting region is located.

8. The vertical cavity surface emitting laser according to claim 1, characterized in that: Each epitaxial layer in the inclined structure is inclined downward or upward relative to the corresponding epitaxial layer in the resonant light emitting region.

9. The vertical cavity surface emitting laser according to claim 1, characterized in that: The oxidized end of the oxide layer in the side mode suppression zone gradually approaches the resonant light-emitting zone at a projection position on a plane where the first surface of the substrate located in the resonant light-emitting zone is located from top to bottom, or the oxidized end of the oxide layer in the side mode suppression zone gradually moves away from the resonant light-emitting zone at a projection position on a plane where the first surface of the substrate located in the resonant light-emitting zone is located from top to bottom.

10. The vertical cavity surface emitting laser according to claim 1, characterized in that: When the second DBR layer is a P-DBR layer and the second electrode is a P-type electrode, a dielectric layer is provided above the P-DBR layer, and the dielectric layer covers the area on the P-DBR layer except the P-type electrode.

11. The vertical cavity surface emitting laser according to claim 10, characterized in that: The thickness of the dielectric layer in the resonant light emitting region is smaller than the thickness of the dielectric layer in the side mode suppression region.

Images