A monolithic multi-wavelength output facet laser structure and method of fabrication

Abstract

The application relates to a monolithic multi-wavelength output surface emitting laser structure and a preparation method thereof. The application comprises a substrate, an N-type DBR mirror layer arranged on the upper surface of the substrate, a first active layer arranged on the upper surface of the N-type DBR mirror layer, a first oxidation layer arranged on the upper surface of the first active layer, at least one intermediate active region structure vertically stacked on the upper surface of the first oxidation layer, each intermediate active region structure comprising an intermediate DBR mirror layer, a second active layer and a second oxidation layer arranged in sequence from bottom to top, a P-type DBR mirror layer arranged on the intermediate active region structure, a P-surface electrode layer arranged on the upper surface of the P-type DBR mirror layer, and an N-surface electrode layer arranged on the lower surface of the substrate. The P-surface electrode layer surface is provided with a central light-emitting hole, and the first oxidation layer and the second oxidation layer are respectively provided with oxidation holes corresponding to the central light-emitting hole. The application increases the types of output wavelengths and has high integration.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronics technology, and in particular to a monolithic multi-wavelength output surface-emitting laser structure and its fabrication method. Background Technology

[0002] With the development of modern society, laser medical technology plays an indispensable role in the field of life and health. Applications such as laser repair, phototherapy, laser hair removal, and even dry eye treatment have placed new demands on the types and intensity of laser output wavelengths. Because traditional vertical-cavity surface-emitting lasers (VCSELs) have a single active quantum well structure, the same laser can only output a beam of one wavelength with limited intensity. A single wavelength beam output has a single therapeutic effect. However, when a red laser beam at approximately 630nm and a near-infrared laser beam at 830nm are output simultaneously, multiple functions can be achieved simultaneously, including the production of ATP (cellular energy), stimulation of cell membranes, acceleration of cell activity, and collagen production. How to simultaneously output more focused and efficient multiple wavelengths of laser light in a vertical-cavity surface-emitting laser has become a research hotspot both domestically and internationally.

[0003] To address the aforementioned issues with VCSEL lasers, a common approach is to arrange multiple VCSEL lasers externally to obtain various laser sources. However, this external arrangement method suffers from drawbacks such as uneven beam distribution, poor beam quality, and high manufacturing costs. Summary of the Invention

[0004] Therefore, the present invention provides a monolithic multi-wavelength output surface-emitting laser structure and fabrication method, which increases the variety of output wavelengths and has high integration.

[0005] To address the aforementioned technical problems, this invention provides a monolithic multi-wavelength output surface-emitting laser structure, comprising:

[0006] Substrate;

[0007] An N-type DBR reflector layer disposed on the upper surface of the substrate;

[0008] The first active layer is disposed on the upper surface of the N-type DBR mirror layer;

[0009] A first oxide layer is disposed on the upper surface of the first active layer;

[0010] At least one intermediate active region structure is vertically stacked on the upper surface of the first oxide layer, and each intermediate active region structure includes an intermediate DBR mirror layer, a second active layer and a second oxide layer arranged sequentially from bottom to top.

[0011] A P-type DBR reflector layer is disposed on the intermediate active region structure;

[0012] The P-side electrode layer is disposed on the upper surface of the P-type DBR reflector layer;

[0013] An N-plane electrode layer is disposed on the lower surface of the substrate;

[0014] The P-side electrode layer has a central light-emitting hole on its surface, and the first oxide layer and the second oxide layer each have oxide holes corresponding to the central light-emitting hole.

[0015] In one embodiment of the present invention, in the first active layer and the second active layer, the emission wavelength of the lower active layer is greater than the emission wavelength of the upper active layer.

[0016] In one embodiment of the present invention, the materials of both the first active layer and the second active layer include one of AlGaAs, AlGaInAs, and GaAs.

[0017] In one embodiment of the present invention, both the first oxide layer and the second oxide layer are AlAs oxide layers.

[0018] In one embodiment of the present invention, the size of the central light-emitting aperture is larger than the size of the oxide aperture.

[0019] In one embodiment of the present invention, the substrate is a GaAs substrate.

[0020] In one embodiment of the present invention, the shapes of the first active layer and the second active layer both include regular polygons and circles.

[0021] This invention also provides a method for fabricating a monolithic multi-wavelength output surface-emitting laser structure, comprising:

[0022] Provide GaAs substrates;

[0023] An N-type DBR reflector layer is formed by alternating N-doped AlGaAs layers with different compositions grown on the surface of the GaAs substrate through metal-organic chemical vapor deposition.

[0024] A first active layer is grown on the surface of the N-type DBR mirror layer;

[0025] A first AlAs oxide layer is grown on the surface of the first active layer;

[0026] An intermediate DBR mirror layer is formed by alternating growth of AlGaAs layers with different compositions on the surface of the first AlAs oxide layer by metal-organic chemical vapor deposition. A second active layer is grown on the surface of the intermediate DBR mirror layer, and a second AlAs oxide layer is grown on the surface of the second active layer.

[0027] P-doped AlGaAs are alternately grown on the surface of the second AlAs oxide layer to form a P-type DBR mirror layer and obtain a VCSEL structure.

[0028] A surface is etched onto the outer side of the VCSEL structure using photolithography.

[0029] Oxidation pores are created at the center of the first oxide layer and the second oxide layer by side oxidation;

[0030] A central light-emitting hole was fabricated on the surface of the VCSEL structure using photolithography.

[0031] A P-side electrode layer is fabricated around the central light-emitting aperture by vapor deposition of metal.

[0032] After thinning and polishing the GaAs substrate, an N-plane electrode layer is deposited on its bottom surface.

[0033] In one embodiment of the present invention, after alternating growth of AlGaAs layers with different compositions on the surface of the first AlAs oxide layer by metal-organic chemical vapor deposition to form an intermediate DBR mirror layer, a second active layer is grown on the surface of the intermediate DBR mirror layer, and a second AlAs oxide layer is grown on the surface of the second active layer; subsequently, the method further includes:

[0034] Repeat the above steps once or multiple times to form multiple sets of intermediate DBR reflector layers, second active layers and second oxide layers vertically stacked on the surface of the AlAs oxide layer, wherein, in the first active layer and the second active layer, the emission wavelength of the lower active layer is greater than the wavelength of the upper active layer.

[0035] In one embodiment of the present invention, the size of the central light-emitting aperture is larger than the size of the oxide aperture.

[0036] The technical solution of the present invention has the following advantages compared with the prior art:

[0037] The present invention discloses a monolithic multi-wavelength output surface-emitting laser structure and fabrication method. The structure has a simple fabrication process and can realize the output of multiple wavelengths at the same output port of the laser. By growing multiple layers of the same or different types of quantum well active regions inside to form a VCSEL laser, the variety of output wavelengths is increased, the integration is higher and the laser diagnosis and treatment effect is more significant.

[0038] In this invention, the design of the quantum well active layer includes the following methods: superimposed growth of the same luminescent material, by adjusting the thickness and composition of the material layers, the desired emission wavelength and photoelectric properties can be achieved; using different luminescent materials, by adjusting the thickness and composition of different material layers, more complex band structures and photoelectric properties can be achieved; different number of growth layers, by gradually increasing or decreasing the number of quantum well active layers, the emission wavelength can be different.

[0039] The multi-wavelength output structure of this invention can be extended to fields including VCSEL lasers, high-power pump lasers, and large-cavity lasers. Attached Figure Description

[0040] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0041] Figure 1 This is a schematic diagram of the monolithic multi-wavelength output surface emitting laser structure in Embodiment 1 of the present invention.

[0042] Figure 2 This is a schematic diagram of the monolithic multi-wavelength output surface emitting laser structure in Embodiment 2 of the present invention.

[0043] Figure 3 This is a side view of the monolithic multi-wavelength output surface-emitting laser structure in Embodiment 2 of the present invention.

[0044] Figure 4 This is a schematic diagram of the manufacturing structure of Embodiment 4 of the present invention.

[0045] Explanation of reference numerals in the instruction manual:

[0046] 1. Substrate; 2. N-type DBR mirror layer; 3. First active layer; 4. First oxide layer; 5. Intermediate active region structure; 6. Intermediate DBR mirror layer; 7. Second active layer; 8. Second oxide layer; 9. P-type DBR mirror layer; 10. P-side electrode layer; 11. N-side electrode layer; 12. Central light-emitting aperture; 13. Oxide aperture; 14. First intermediate DBR mirror layer; 15. Second intermediate DBR mirror layer; 16. Third active layer; 17. Third oxide layer;

[0047] 101. GaAs substrate;

[0048] 102. N-type DBR reflector layer;

[0049] 103. First active layer;

[0050] 104. First AlAs oxide layer;

[0051] 105. Intermediate DBR reflector layer;

[0052] 106. Second active layer;

[0053] 107. Second AlAs oxide layer;

[0054] 108. P-type DBR reflector layer;

[0055] 109. Countertop;

[0056] 110. Oxidation pores;

[0057] 111. Center light-emitting aperture;

[0058] 112. P-side electrode layer;

[0059] 113. N-face electrode layer. Detailed Implementation

[0060] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0061] In this invention, when directions (up, down, left, right, front, and back) are described, it is only for the convenience of describing the technical solution of this invention, and does not indicate or imply that the technical features referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0062] In this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc., are understood to exclude the stated number; "above," "below," "within," etc., are understood to include the stated number. In the description of this invention, the terms "first" and "second" are used only to distinguish technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0063] In this invention, unless otherwise explicitly defined, the terms "setting," "installing," and "connecting" should be interpreted broadly. For example, they can refer to a direct connection or an indirect connection through an intermediate medium; a fixed connection, a detachable connection, or an integrally formed connection; a mechanical connection, an electrical connection, or a connection capable of mutual communication; or the internal connection of two components or the interaction between two components. Those skilled in the art can reasonably determine the specific meaning of the above terms in this invention based on the specific content of the technical solution.

[0064] Example 1

[0065] Reference Figure 1As shown, a monolithic multi-wavelength output surface-emitting laser structure includes:

[0066] Substrate 1;

[0067] N-type DBR reflector layer 2 disposed on the upper surface of the substrate 1;

[0068] The first active layer 3 is disposed on the upper surface of the N-type DBR reflector layer 2;

[0069] The first oxide layer 4 is disposed on the upper surface of the first active layer 3;

[0070] The intermediate DBR reflector layer 6, the second active layer 7, and the second oxide layer 8 are sequentially disposed on the upper surface of the first oxide layer 4.

[0071] P-type DBR reflector layer 9 is disposed on the upper surface of the second oxide layer 8;

[0072] P-surface electrode layer 10 is disposed on the upper surface of P-type DBR reflector layer 9;

[0073] N-side electrode layer 11 is disposed on the lower surface of the substrate 1;

[0074] The P-side electrode layer 10 has a central light-emitting hole 12 on its surface, and the first oxide layer 4 and the second oxide layer 8 have oxide holes 13 respectively corresponding to the central light-emitting hole 12.

[0075] Specifically, the emission wavelength of the first active layer 3 is greater than that of the second active layer 7, so as to avoid the strong light absorption effect of the second active layer 7.

[0076] Specifically, the materials of the first active layer 3 and the second active layer 7 both include one of AlGaAs, AlGaInAs, and GaAs.

[0077] Specifically, both the first oxide layer 4 and the second oxide layer 8 are AlAs oxide layers.

[0078] Specifically, the size of the central light-emitting aperture 12 is larger than the size of the oxide aperture 13.

[0079] Specifically, the substrate 1 is a GaAs substrate 1.

[0080] Specifically, the shapes of the first active layer 3 and the second active layer 7 include regular polygons and circles, and can also be trapezoids or other feasible shapes.

[0081] Example 2

[0082] Reference Figure 2 and Figure 3As shown, a monolithic multi-wavelength output surface-emitting laser structure includes:

[0083] Substrate 1;

[0084] N-type DBR reflector layer 2 disposed on the upper surface of the substrate 1;

[0085] The first active layer 3 is disposed on the upper surface of the N-type DBR reflector layer 2;

[0086] The first oxide layer 4 is disposed on the upper surface of the first active layer 3;

[0087] A first intermediate DBR reflector layer 14, a second active layer 7, a second oxide layer 8, a second intermediate DBR reflector layer 15, a third active layer 16 and a third oxide layer 17 are sequentially disposed on the upper surface of the first oxide layer 4.

[0088] P-type DBR reflector layer 9 is disposed on the upper surface of the third oxide layer 17;

[0089] P-surface electrode layer 10 is disposed on the upper surface of P-type DBR reflector layer 9;

[0090] N-side electrode layer 11 is disposed on the lower surface of the substrate 1;

[0091] The P-side electrode layer 10 has a central light-emitting hole 12 on its surface, and the first oxide layer 4, the second oxide layer 8 and the third oxide layer 17 have oxide holes 13 respectively corresponding to the central light-emitting hole 12.

[0092] Specifically, the emission wavelength of the first active layer 3 is greater than that of the second active layer 7, and the emission wavelength of the second active layer 7 is greater than that of the third active layer 16, so as to avoid the strong light absorption effect of the third active layer 16.

[0093] Specifically, the materials of the first active layer 3, the second active layer 7, and the third active layer 16 all include one of AlGaAs, AlGaInAs, and GaAs.

[0094] Specifically, the first oxide layer 4, the second oxide layer 8, and the third oxide layer 17 are all AlAs oxide layers.

[0095] Specifically, the size of the central light-emitting aperture 12 is larger than the size of the oxide aperture 13.

[0096] Specifically, the substrate 1 is a GaAs substrate 1.

[0097] Specifically, the shapes of the first active layer 3, the second active layer 7, and the third active layer 16 all include regular polygons and circles, and can also be trapezoids or other shapes.

[0098] Example 3

[0099] This embodiment of a monolithic multi-wavelength output surface-emitting laser structure is similar to the structures of Embodiments 1 and 2, except that more (three or more) intermediate active region structures 5 are provided on the upper surface of the first oxide layer 4, specifically including:

[0100] Substrate 1;

[0101] N-type DBR reflector layer 2 disposed on the upper surface of the substrate 1;

[0102] The first active layer 3 is disposed on the upper surface of the N-type DBR reflector layer 2;

[0103] The first oxide layer 4 is disposed on the upper surface of the first active layer 3;

[0104] At least three intermediate active region structures 5 are vertically stacked on the upper surface of the first oxide layer 4. Each intermediate active region structure 5 includes an intermediate DBR reflector layer 6, a second active layer 7, and a second oxide layer 8 arranged sequentially from bottom to top.

[0105] P-type DBR reflector layer 9 is disposed on the intermediate active region structure 5;

[0106] P-surface electrode layer 10 is disposed on the upper surface of P-type DBR reflector layer 9;

[0107] N-side electrode layer 11 is disposed on the lower surface of the substrate 1;

[0108] The P-side electrode layer 10 has a central light-emitting hole 12 on its surface, and the first oxide layer 4 and the second oxide layer 8 have oxide holes 13 respectively corresponding to the central light-emitting hole 12.

[0109] Specifically, in the first active layer 3 and the second active layer 7, the emission wavelength of the lower active layer is greater than that of the upper active layer.

[0110] One method to achieve reflection of both wavelengths is to use a Dip-Bracket reflector (DBR). A Bragg reflector is composed of a series of alternating high- and low-refractive-index materials. The thickness and refractive index of these materials are chosen so that light of a specific wavelength undergoes multiple reflections within the reflector, resulting in coherent interference and the formation of reflection peaks. To achieve reflection of both wavelengths, a double-period Bragg reflector structure can be used. A double-period Bragg reflector consists of two alternating periods of high- and low-refractive-index materials. This structure can simultaneously satisfy the reflection requirements of both wavelengths. Furthermore, by adjusting the thickness and refractive index of the high- and low-refractive-index materials in the Bragg reflector, reflection of even more wavelengths can be achieved; this method allows for the design of multi-wavelength reflectors as needed.

[0111] Specifically, the materials of the first active layer 3 and the second active layer 7 both include one of AlGaAs, AlGaInAs, and GaAs. The design of the quantum well active layer includes the following methods: superimposed growth of the same luminescent material, by adjusting the thickness and composition of the material layers, the desired emission wavelength and photoelectric properties can be achieved; using different luminescent materials, by adjusting the thickness and composition of different material layers, more complex band structures and photoelectric properties can be achieved; different number of growth layers, by gradually increasing or decreasing the number of quantum well active layers, different emission wavelengths can be achieved.

[0112] Specifically, the first oxide layer 4 and the second oxide layer 8 are both AlAs oxide layers, the size of the central light-emitting hole 12 is larger than the size of the oxide hole 13, and the substrate 1 is a GaAs substrate 1.

[0113] Specifically, the shapes of the first active layer 3 and the second active layer 7 include regular polygons and circles, and can also be trapezoids or other feasible shapes.

[0114] Example 4

[0115] Reference Figure 4 As shown, this embodiment provides a method for fabricating a monolithic multi-wavelength output surface-emitting laser structure, including:

[0116] S1. Provide a GaAs substrate 101;

[0117] S2. An N-type DBR mirror layer 102 is formed by alternating N-doped AlGaAs layers with different compositions grown on the upper surface of the GaAs substrate 101 through metal-organic chemical vapor deposition.

[0118] S3. A first active layer 103 is grown on the surface of the N-type DBR mirror layer 102;

[0119] S4. A first AlAs oxide layer 104 is grown on the surface of the first active layer 103;

[0120] S5. AlGaAs layers with different compositions are alternately grown on the surface of the first AlAs oxide layer 104 by metal-organic chemical vapor deposition to form an intermediate DBR mirror layer 105. A second active layer 106 is grown on the surface of the intermediate DBR mirror layer 105, and a second AlAs oxide layer 107 is grown on the surface of the second active layer 106.

[0121] S6. P-doped AlGaAs are alternately grown on the surface of the second AlAs oxide layer 107 to form a P-type DBR mirror layer 108 and obtain a VCSEL structure.

[0122] S7. The surface 109 is etched onto the outer side of the VCSEL structure by photolithography;

[0123] S8. An oxide hole 110 is formed in the center of the first oxide layer and the second oxide layer by side oxidation;

[0124] S9. A central light-emitting hole 111 is fabricated on the surface of the VCSEL structure by photolithography;

[0125] S10. A P-surface electrode layer 112 is formed around the central light-emitting hole 111 by vapor deposition of metal.

[0126] S11. After thinning and polishing the GaAs substrate 101, an N-side electrode layer 113 is deposited on its bottom surface.

[0127] The structure described in Example 1 can be obtained using the above preparation method.

[0128] Specifically, after step S5, the method further includes: repeating step S5 once or multiple times to form multiple sets of intermediate DBR reflector layers 105, second active layers 106, and second oxide layers vertically stacked on the surface of the AlAs oxide layer. In the first active layer 103 and the second active layer 106, the emission wavelength of the lower active layer is greater than that of the upper active layer. This results in a structure similar to that in Embodiment 2 or Embodiment 3.

[0129] The above structure has a simple manufacturing process and can achieve multiple wavelengths output from the same output port of the laser. By growing multiple layers of the same or different types of quantum well active regions inside to form a VCSEL laser, the variety of output wavelengths is increased, the integration is higher, and the laser diagnosis and treatment effect is more significant.

[0130] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A monolithic multi-wavelength output surface-emitting laser structure, characterized in that, include: Substrate; An N-type DBR reflector layer disposed on the upper surface of the substrate; The first active layer is disposed on the upper surface of the N-type DBR mirror layer; A first oxide layer is disposed on the upper surface of the first active layer; At least one intermediate active region structure is vertically stacked on the upper surface of the first oxide layer, and each intermediate active region structure includes an intermediate DBR mirror layer, a second active layer and a second oxide layer arranged sequentially from bottom to top. A P-type DBR reflector layer is disposed on the intermediate active region structure; The P-side electrode layer is disposed on the upper surface of the P-type DBR reflector layer; An N-plane electrode layer is disposed on the lower surface of the substrate; The P-side electrode layer has a central light-emitting hole on its surface, and the first oxide layer and the second oxide layer each have oxide holes corresponding to the central light-emitting hole.

2. The monolithic multi-wavelength output surface-emitting laser structure according to claim 1, characterized in that, In the first active layer and the second active layer, the emission wavelength of the lower active layer is greater than that of the upper active layer.

3. The monolithic multi-wavelength output surface-emitting laser structure according to claim 1, characterized in that, The materials of both the first active layer and the second active layer include one of AlGaAs, AlGaInAs, and GaAs.

4. The monolithic multi-wavelength output surface-emitting laser structure according to claim 1, characterized in that, Both the first oxide layer and the second oxide layer are AlAs oxide layers.

5. The monolithic multi-wavelength output surface-emitting laser structure according to claim 1, characterized in that, The size of the central light-emitting aperture is larger than the size of the oxide aperture.

6. The monolithic multi-wavelength output surface-emitting laser structure according to claim 1, characterized in that, The substrate is a GaAs substrate.

7. The monolithic multi-wavelength output surface-emitting laser structure according to claim 1, characterized in that, The shapes of both the first active layer and the second active layer include regular polygons and circles.

8. A method for fabricating a monolithic multi-wavelength output surface-emitting laser structure, characterized in that, include: Provide GaAs substrates; An N-type DBR reflector layer is formed by alternating N-doped AlGaAs layers with different compositions grown on the surface of the GaAs substrate through metal-organic chemical vapor deposition. A first active layer is grown on the surface of the N-type DBR mirror layer; A first AlAs oxide layer is grown on the surface of the first active layer; An intermediate DBR mirror layer is formed by alternating growth of AlGaAs layers with different compositions on the surface of the first AlAs oxide layer by metal-organic chemical vapor deposition. A second active layer is grown on the surface of the intermediate DBR mirror layer, and a second AlAs oxide layer is grown on the surface of the second active layer. P-doped AlGaAs are alternately grown on the surface of the second AlAs oxide layer to form a P-type DBR mirror layer and obtain a VCSEL structure. A surface is etched onto the outer side of the VCSEL structure using photolithography. Oxidation pores are created at the center of the first oxide layer and the second oxide layer by side oxidation; A central light-emitting hole was fabricated on the surface of the VCSEL structure using photolithography. A P-side electrode layer is fabricated around the central light-emitting aperture by vapor deposition of metal. After thinning and polishing the GaAs substrate, an N-plane electrode layer is deposited on its bottom surface.

9. The method for fabricating a monolithic multi-wavelength output surface-emitting laser structure as described in claim 8, characterized in that, After alternating growth of AlGaAs layers with different compositions on the surface of the first AlAs oxide layer via metal-organic chemical vapor deposition to form an intermediate DBR mirror layer, a second active layer is grown on the surface of the intermediate DBR mirror layer, and a second AlAs oxide layer is grown on the surface of the second active layer; subsequently, the process further includes: Repeat the above steps once or multiple times to form multiple sets of intermediate DBR reflector layers, second active layers and second oxide layers vertically stacked on the surface of the AlAs oxide layer, wherein, in the first active layer and the second active layer, the emission wavelength of the lower active layer is greater than the wavelength of the upper active layer.

10. The method for fabricating a monolithic multi-wavelength output surface-emitting laser structure as described in claim 8, characterized in that, The size of the central light-emitting aperture is larger than the size of the oxide aperture.

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