A high-performance VCSEL semiconductor laser based on a diamond film

Abstract

The application belongs to the technical field of semiconductor laser, and relates to a high-performance VCSEL semiconductor laser based on a diamond film. The application aims to solve the problems of low working temperature (600), wide line width and poor beam quality of the VCSEL. The main scheme comprises a substrate (101), a heat dissipation layer (102), a first electrode (103), a first DBR reflection layer (104), a first oxidation limiting layer (105), an active layer (106), a second oxidation limiting layer (107), a second DBR reflection layer (108), and an insulating heat dissipation layer (109) arranged from bottom to top. The insulating heat dissipation layer (109) is provided with a second electrode (110) connected with the second DBR reflection layer (108), and the second electrode is covered with a heat insulation layer.

Description

Technical Field

[0001] This invention relates to the field of semiconductor laser technology, specifically a high-performance VCSEL semiconductor laser based on a diamond film. Background Technology

[0002] Nuclear magnetic resonance gyroscopes (NMR gyroscopes) and SERF atomic magnetometers are precision sensors for measuring inertia and magnetic fields in quantum sensing, possessing the potential for both high precision and miniaturization, making them a research hotspot in recent years. Domestic research on NMR gyroscopes and SERF atomic magnetometers has progressed rapidly in recent years. However, the main obstacle to further miniaturization and high precision development of NMR gyroscopes and magnetometers is the use of high-temperature, high-stability, and high-performance semiconductor lasers, most of which are vertical-cavity surface-emitting lasers (VCSELs). These two types of sensors can operate at temperatures exceeding 100°C. Increased temperature reduces the gain of individual quantum wells, causes material strain, and ultimately reduces output power, alters the output wavelength, and affects operational stability and lifespan. Therefore, effective heat dissipation of semiconductor lasers is crucial for improving their output power and efficiency, enhancing beam quality, and extending lifespan. Solving the technical challenges of semiconductor lasers is essential to improving the performance of quantum sensors.

[0003] Vertical-cavity surface-emitting lasers (VCSELs) are miniaturized, high-precision semiconductor lasers with many unique characteristics, such as high beam quality, high fiber affinity, good optoelectronic integration, ease of implementation in two-dimensional arrays, and low susceptibility to optical catastrophes during operation. They are widely used in devices such as atomic clocks, atomic gyroscopes, and atomic magnetometers. However, currently, domestically produced VCSELs have relatively low operating temperatures (600°C), wide linewidths, poor beam quality, and short lifespans. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of low operating temperature (600°C), wide linewidth, and poor beam quality of VCSELs.

[0005] To achieve the above objectives, the present invention employs the following technical means:

[0006] A high-performance VCSEL semiconductor laser based on diamond film includes, from bottom to top, a substrate, a heat dissipation layer, a first electrode, a first DBR reflective layer, a first oxide confinement layer, an active layer, a second oxide confinement layer, a second DBR reflective layer, and an insulating heat dissipation layer. A second electrode connected to the second DBR reflective layer is disposed on the insulating heat dissipation layer, and a heat insulation layer is covered on the second electrode.

[0007] In the above technical solution, the first oxide confinement layer is disposed on the first DBR reflective layer and located at both ends of the first DBR reflective layer.

[0008] In the above technical solution, the second oxidation confinement layer is disposed on the active layer and located at both ends of the active layer.

[0009] In the above technical solution, the insulating heat dissipation layer is a composite film made of diamond and oxide.

[0010] In the above technical solution, the heat dissipation layer is disposed at both ends of the second DBR reflective layer.

[0011] In the above technical solution, the first DBR reflective layer includes alternating layers of materials with different refractive indices, wherein the effective optical thickness of each alternating layer is an odd integer multiple of one-quarter of the operating wavelength of the vertical cavity surface-emitting laser, that is, the effective optical thickness of each alternating layer is one-quarter of an odd integer multiple of the operating wavelength of the vertical cavity surface-emitting laser.

[0012] In the above technical solution, the active layer includes a stacked quantum well composite structure, which is composed of barrier material and potential well material stacked together. The active layer is used to convert electrical energy into light energy and includes one or more nitride semiconductor layers. The nitride semiconductor layer includes one or more quantum well layers or one or more quantum dot layers sandwiched between corresponding pairs of barrier layers.

[0013] Because the present invention employs the above-mentioned technical means, it has the following beneficial effects:

[0014] This invention utilizes chemical vapor deposition (CVD) to deposit a diamond film as a heat dissipation layer on a substrate, which is more convenient than the previous method of removing the substrate before preparing the heat sink. A diamond / oxide composite film is epitaxially grown on the second DBR reflective layer as an insulating heat dissipation layer. The high thermal conductivity of the diamond film in both the heat dissipation layer and the insulating layer dissipates the heat generated within the laser into the external environment, thereby improving its output power and efficiency, enhancing beam quality, and extending its lifespan. Therefore, this VCSEL can be applied to atomic gyroscopes and magnetometers.

[0015] This invention effectively improves heat dissipation and insulation efficiency by analyzing the mechanisms of each active layer, ohmic contact layer, and distributed Bragg reflector (DBR) and adding two layers of diamond and sapphire films. The bandgap of semiconductor materials changes with temperature; generally, higher temperatures result in a smaller bandgap and a larger output wavelength for the fabricated laser. With increased heat dissipation and insulation efficiency, the internal temperature change of the VCSEL during device operation decreases, and the degree of change in the bandgap of the active semiconductor material also decreases. This leads to a more stable lasing wavelength in the semiconductor laser, enabling the laser to operate at high temperatures while achieving good beam quality and narrow linewidth. Designing the VCSEL structure to improve its heat dissipation and insulation efficiency reduces the heat generated by internal thermal effects in high-power VCSELs while isolating heat transferred from the heated atomic gas chamber, thereby improving its performance and making it better suited for applications such as nuclear magnetic resonance gyroscopes and SERF atomic magnetometers. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a VCSEL-based nuclear magnetic resonance gyroscope.

[0017] Figure 2 This is a schematic diagram of the VCSEL semiconductor laser in this invention.

[0018] Explanation of reference numerals in the attached figures

[0019] Substrate-101, heat dissipation layer-102, first electrode-103, first DBR reflective layer-104, first oxide confinement layer-105, active layer-106, second oxide confinement layer-107, second DBR reflective layer-108, insulating heat dissipation layer-109, second electrode-110, heat insulation layer-111. Detailed Implementation

[0020] The embodiments of the present invention will be described in detail below. Although the present invention will be described and illustrated in conjunction with some specific embodiments, it should be noted that the present invention is not limited to these embodiments. On the contrary, any modifications or equivalent substitutions made to the present invention should be covered within the scope of the claims of the present invention.

[0021] Furthermore, to better illustrate the present invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art will understand that the present invention can be implemented without these specific details. It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show components related to the present invention and are not drawn according to the actual number, shape, and size of components in implementation. In actual implementation, the form, quantity, and proportion of each component can be arbitrarily changed, and the component layout may also be more complex.

[0022] The high-performance VCSEL semiconductor laser S1 based on diamond film can be used as a pump source and detection source for atomic gyroscopes or magnetometers. It is composed of a substrate 101, a heat dissipation layer 102, a first electrode 103, a first DBR reflective layer 104, a first oxide confinement layer 105, an active layer 106, a second oxide confinement layer 107, a second DBR reflective layer 108, an insulating heat dissipation layer 109, a second electrode 110, and a heat insulation layer 111.

[0023] The substrate 101 can be any material suitable for forming a vertical cavity surface-emitting laser. It can be an N-type doped semiconductor substrate or a P-type doped semiconductor substrate. Doping can reduce the contact resistance of the ohmic contact between the subsequently formed electrode and the semiconductor substrate. In some embodiments, the substrate 101 can be a sapphire substrate or a substrate of other materials, or at least the top surface of the substrate 101 is composed of one of Si, GaAs, silicon carbide, aluminum nitride, and gallium nitride.

[0024] The heat dissipation layer 102 is a diamond film. The heat dissipation layer 102 connects the substrate 101 and the first electrode 103. The thickness of the heat dissipation layer can be 300-600 nm. The function of the heat dissipation layer 102 is to dissipate the heat generated by the active layer 106 and the reflective layer during operation through the substrate 101. In this embodiment, a diamond film is deposited on the substrate 101 as the heat dissipation layer 102 using chemical vapor deposition.

[0025] The first electrode 103 is, for example, an N-type electrode, and the first electrode 103 is, for example, a cathode. The material of the first electrode 103 may include one or a combination of Au metal, Ag metal, Pt metal, Ti metal, and Ni metal.

[0026] A first DBR reflective layer 104 is formed on the first electrode 103. The first DBR reflective layer 104 may be composed of, for example, layers of two materials with different refractive indices, including AlGaAs and GaAs, or AlGaAs with high aluminum content and AlGaAs with low aluminum content. The first reflective layer 104 is an N-type Bragg mirror. In some embodiments, the first DBR reflective layer 104 includes a series of alternating layers of materials with different refractive indices, wherein the effective optical thickness of each alternating layer (the layer thickness multiplied by the layer refractive index) is an odd integer multiple of one-quarter of the operating wavelength of the vertical-cavity surface-emitting laser, that is, the effective optical thickness of each alternating layer is one-quarter of an odd integer multiple of the operating wavelength of the vertical-cavity surface-emitting laser.

[0027] The first oxide confinement layer 105 is grown on the first DBR reflective layer 104. The first oxide confinement layer 105 can be epitaxially grown using GaAs or materials with GaAs lattice constant matching, such as AlGaAs, InGaP, InAlP, InGaAIP, GaInNAs, etc., and after wet or dry oxidation, it is transformed into a low-refractive-index amorphous and electrically insulating oxide, forming the first oxide confinement layer 105 with a layered epitaxial structure. The first oxide confinement layer 105 is located at both ends of the first DBR reflective layer 104.

[0028] An active layer 106 is formed on the first oxide confinement layer 105. The active layer 106 includes a stacked quantum well composite structure, composed of barrier and well materials arranged in a stacked manner, used to convert electrical energy into light energy. The active layer 106 can be made of GaAs and AlGaAs, or InGaAs and AlGaAs. The active layer 106 can also be made of I1-V group materials such as GaP, GaAs, AlGaAs, InGaAs, InGaAsP, AlGaInAs, AlSb, AlGaN, AlAs, InP, GaSb, InAs, and InSb. The active layer 106 is used to generate light.

[0029] The active layer 106 is located between the first oxide confinement layer 105 and the second oxide confinement layer 107. The second oxide confinement layer 107 can be epitaxially grown using GaAs or materials with GaAs lattice constant matching, such as AlGaAs, InGaP, InAlP, InGaAlP, GaInNAs, etc., and after wet or dry oxidation, it is transformed into a low-refractive-index amorphous and electrically insulating oxide, forming the second oxide confinement layer 107 with a layered epitaxial structure. The second oxide confinement layer 107 is located at both ends of the active layer 106.

[0030] The second DBR reflective layer 108 may be constructed from a stack of two materials with different refractive indices, such as AlGaAs and GaAs, or AlGaAs with high aluminum content and AlGaAs with low aluminum content. The second DBR reflective layer 108 is a P-type Bragg mirror. In some embodiments, the second DBR reflective layer 108 comprises a series of alternating layers of materials with different refractive indices, wherein the effective optical thickness of each alternating layer (the layer thickness multiplied by the layer's refractive index) is an odd integer multiple of one-quarter of the operating wavelength of the vertical-cavity surface-emitting laser (VCSEL). The second DBR reflective layer 108 has a higher reflectivity than the first DBR reflective layer 104. The first DBR reflective layer 104 and the second DBR reflective layer 108 are used to reflect and enhance the light generated by the active layer 106, which is then emitted from the surface of the first DBR reflective layer 104.

[0031] After forming the second DBR reflective layer 108, an insulating heat dissipation layer 109 is then formed on the second DBR reflective layer 108. Following the formation of the insulating heat dissipation layer 109, an opening is formed in the second DBR reflective layer 108, that is, a portion of the second DBR reflective layer 108 is exposed by etching a portion of the insulating heat dissipation layer 109, such that the insulating heat dissipation layer is located at both ends of the second DBR reflective layer 108. This opening allows the subsequent second electrode 110 to connect to the second DBR reflective layer 108. The insulating heat dissipation layer 109 is made of a composite of diamond and SiN, SiO2, AlO2, or other insulating materials, and its thickness can be 100-300 nm. In this embodiment, the insulating heat dissipation layer 109 can be formed, for example, by chemical vapor deposition.

[0032] The second electrode 110 is located on the insulating heat dissipation layer 109, and the second electrode 110 contacts the second DBR reflective layer 108 through an opening. When a current is applied to the first electrode 103 and the second electrode 110, the active layer 106 emits a laser beam. The second electrode 110 is, for example, a P-type electrode, and the material of the second electrode 110 may include one or a combination of Au metal, Ag metal, Pt metal, Ge metal, Ti metal, and Ni metal.

[0033] A heat insulation layer 111 is disposed on the second electrode 110 and is made of transparent sapphire glass. When the VCSEL generates laser light, it is emitted from the opening and passes through the heat insulation layer 111. When used in a nuclear magnetic resonance gyroscope or atomic magnetometer, the laser is affected by the temperature generated by the heating of the alkali metal gas chamber. The heat insulation layer 111 utilizes the thermal conductivity of sapphire glass to dissipate the heat into the environment, reducing the impact of high temperature on the active layer 106 and the DBR reflective layers 104 and 108, thereby achieving the purpose of heat insulation.

[0034] The above description is merely a preferred embodiment of this application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept. For example, technical solutions formed by replacing the above-mentioned features with technical features with similar functions disclosed in this application (but not limited to) each other.

[0035] Apart from the technical features described in the specification, the other technical features are known to those skilled in the art. To highlight the innovative features of this invention, the other technical features will not be described in detail here.

Claims

1. A high-performance VCSEL semiconductor laser based on diamond film, characterized in that, The structure includes, from bottom to top, a substrate (101), a heat dissipation layer (102), a first electrode (103), a first DBR reflective layer (104), a first oxide confinement layer (105), an active layer (106), a second oxide confinement layer (107), a second DBR reflective layer (108), and an insulating heat dissipation layer (109). A second electrode (110) connected to the second DBR reflective layer (108) is disposed on the insulating heat dissipation layer (109), and a heat insulation layer is covered on the second electrode. The insulating heat dissipation layer (109) is a composite film made of diamond and oxide; The insulation layer is made of sapphire glass; The heat dissipation layer (102) is formed by depositing a diamond film on a substrate using chemical vapor deposition.

2. The high-performance VCSEL semiconductor laser based on diamond film according to claim 1, characterized in that, The first oxidation confinement layer (105) is disposed on the first DBR reflective layer (104) and located at both ends of the first DBR reflective layer (104).

3. A high-performance VCSEL semiconductor laser based on a diamond film according to claim 1, characterized in that, A second oxidation confinement layer (107) is disposed on the active layer (106) and located at both ends of the active layer (106).

4. A high-performance VCSEL semiconductor laser based on a diamond film according to claim 1, characterized in that, The insulating heat dissipation layer (109) is a composite film made of diamond and oxide.

5. A high-performance VCSEL semiconductor laser based on a diamond film according to claim 1, characterized in that, The insulating heat dissipation layer (109) is disposed at both ends of the second DBR reflective layer (108).

6. A high-performance VCSEL semiconductor laser based on a diamond film according to claim 1, characterized in that, The first DBR reflective layer (104) includes alternating layers of materials with different refractive indices, wherein the effective optical thickness of each alternating layer is an odd integer multiple of one-quarter of the operating wavelength of the vertical cavity surface-emitting laser, that is, the effective optical thickness of each alternating layer is one-quarter of an odd integer multiple of the operating wavelength of the vertical cavity surface-emitting laser.

7. A high-performance VCSEL semiconductor laser based on a diamond film according to claim 1, characterized in that, The active layer (106) includes a stacked quantum well composite structure, which is composed of a barrier material and a well material stacked together. The active layer (106) is used to convert electrical energy into light energy and includes one or more nitride semiconductor layers, which include one or more quantum well layers or one or more quantum dot layers sandwiched between corresponding pairs of barrier layers.

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