A coupled cavity vertical cavity surface emitting laser, a preparation method and applications thereof

Abstract

This invention discloses a coupled-cavity vertical-cavity surface-emitting laser (VCSEL), its fabrication method, and its applications, relating to the field of semiconductor technology. Specifically, it addresses the limitation of existing VCSELs due to their short effective cavity length and large spectral linewidth. The laser, from top to bottom, comprises a first Bragg mirror group, an oxide layer, an active region, a second Bragg mirror group, a passive cavity, a third Bragg mirror group, and a substrate. A first electrode is located on the side of the first Bragg mirror group away from the oxide layer, and second electrodes are located at both ends of the passive cavity on the side closest to the second Bragg mirror group. It exhibits superior performance, with a relatively long cavity length and a linewidth less than 20 MHz, which is more than two orders of magnitude smaller than the linewidth of traditional VCSELs, allowing for a wider range of applications.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, specifically to a coupled-cavity vertical-cavity surface-emitting laser, its fabrication method, and its applications. Background Technology

[0002] Since its introduction in 1978, the Vertical-Cavity Surface-Emitting Laser (VCSEL) has experienced rapid development. It possesses many advantages that traditional edge-emitting lasers cannot match, such as small size, low threshold current, high conversion efficiency, good longitudinal mode uniformity, a circular output spot, on-chip testing capability, and ease of integration into large-area arrays. Based on these advantages, VCSELs have rapidly captured the semiconductor laser market in recent years, playing a crucial role in optical communication, sensing, and storage. Meanwhile, atomic clocks are advanced timing devices with an accuracy of only one second per 20 million years, widely used in global navigation systems. Atomic clock sensors rely on the spectral analysis of alkali atoms (rubidium or cesium), which reside in small vapor chambers. The corresponding spectral wavelengths for cesium are 894.6 nm (D1) and 852.3 nm (D2), and for rubidium, 795.0 nm (D1) and 780.2 nm (D2). Vertical-cavity surface-emitting lasers (VCSELs) are the preferred light source for atomic clocks due to their low power consumption and circular output beam characteristics.

[0003] To improve the accuracy and stability of atomic clock sensors, vertical-cavity surface-emitting lasers (VCSELs) must possess characteristics such as a single longitudinal mode corresponding to the characteristic spectral lines of alkali atoms, a narrow spectral linewidth, a fundamental transverse mode, and stable linear polarization. However, traditional VCSELs, due to their inherent structure and manufacturing processes, have a short effective cavity length, typically around one wavelength. This results in a short intrinsic photon lifetime within the cavity, making it difficult to achieve a linewidth of less than 20 MHz, which negatively impacts the application of atomic clocks.

[0004] It is evident that existing vertical-cavity surface-emitting lasers, due to their short effective cavity length and large linewidth, would result in poor atomic clock performance when applied to the field of atomic clocks, thus limiting their application. Summary of the Invention

[0005] This invention aims to solve the problem that existing vertical-cavity surface-emitting lasers (VCSELs) have limited applications due to their short effective cavity length and large spectral linewidth. This invention extends the effective cavity length of the resonant cavity to about 8 μm by setting up three sets of Bragg mirrors and introducing a passive cavity, thereby increasing the intrinsic photon lifetime within the cavity. It has excellent performance, with a longer cavity length and a linewidth of less than 20 MHz, which is more than two orders of magnitude smaller than the linewidth of traditional VCSELs, and can be applied in a wider range of fields.

[0006] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0007] A coupled-cavity vertical-cavity surface-emitting laser (VCSEL) comprises, from top to bottom, a first Bragg mirror group, an oxide layer, an active region, a second Bragg mirror group, a passive cavity, a third Bragg mirror group, and a substrate. A first electrode is disposed on the side of the first Bragg mirror group away from the oxide layer. Second electrodes are disposed at both ends of the passive cavity on the side closest to the second Bragg mirror group. The reflectivity of the first Bragg mirror group is 99.3%–99.6%, the reflectivity of the second Bragg mirror group is 70%–85%, and the reflectivity of the third Bragg mirror group is 99.9%.

[0008] Optionally, the first Bragg mirror group includes 18 to 25 pairs of p-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 2×10 18 cm -3 ~3×10 18 cm -3 .

[0009] Optionally, the second Bragg mirror assembly comprises a three-layer structure, all of which are n-type doped, from bottom to top.

[0010] Optionally, the three-layer structure includes a bottom layer, a middle layer, and a top layer from bottom to top, wherein the bottom layer consists of 8 to 12 pairs of Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 0.5 × 10⁻⁶ 18 cm -3～ 1.5×10 18 cm -3 The intermediate layer is Al. 0.16 Ga 0.84 As layer, doped at a concentration of 1×10⁻⁶ 18 cm -3 ~2×10 18 cm -3 The top layer consists of 6 to 8 pairs of Al 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.5 × 10⁻⁶ 18 cm -3 ~2×10 18 cm -3 .

[0011] Optionally, the third Bragg mirror group comprises 34 to 38 pairs of n-type doped Al.0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.5 × 10⁻⁶ 18 cm -3 ~2×10 18 cm -3 .

[0012] Optionally, the passive cavity is Al. 0.16 Ga 0.84 As, doping concentration is 0.8 × 10⁻⁶ 18 cm -3 ~1.2×

[0013] 10 18 cm -3 .

[0014] Optionally, the thickness of the passive cavity is 1.5 to 2.25 μm.

[0015] Optionally, the substrate is a GaAs substrate.

[0016] This invention also provides a method for fabricating a coupled-cavity vertical-cavity surface-emitting laser, comprising the following steps:

[0017] S1. Epitaxially grow a third Bragg mirror group, a passive cavity, a second Bragg mirror group, an active region, an oxide layer, and a first Bragg mirror group on a substrate in sequence to obtain a first preform.

[0018] S2. A first electrode is disposed on the first Bragg reflector group of the first preform, and a second electrode is disposed on the passive cavity of the first preform to complete the fabrication of the laser.

[0019] The present invention also provides an application of a coupled-cavity vertical-cavity surface-emitting laser prepared by the above-described method or by the above-described method.

[0020] Compared with the prior art, the advantages of the present invention are as follows:

[0021] 1. The present invention relates to a coupled-cavity vertical-cavity surface-emitting laser (VCSEL), which incorporates three sets of Bragg mirrors and introduces a passive cavity. The reflectivity of the three sets of Bragg mirrors is set with different parameters: the reflectivity of the bottom third Bragg mirror set is limited to 99.9%; the reflectivity of the middle second Bragg mirror set is limited to between 70% and 85%; and the reflectivity of the top first Bragg mirror set is limited to between 99.3% and 99.6%. This allows photons to repeatedly circulate within the passive cavity between the bottom and middle Bragg mirror sets. The optical field within the passive cavity is higher than that in the active region, increasing the photon lifetime within the cavity. Consequently, the linewidth can reach less than 20 MHz, which is more than two orders of magnitude smaller than that of conventional VCSELs.

[0022] Because this invention features a three-mirror cavity structure, the effective coupling cavity length of the laser is increased to approximately 8 μm, and the cold cavity linewidth Δλc can reach 0.01397 nm. Furthermore, the passive cavity within the laser maintains modal purity, preventing lasing from occurring in all modes except for a single longitudinal mode, thus resulting in higher laser performance.

[0023] 2. The present invention relates to a method for fabricating a coupled-cavity vertical-cavity surface-emitting laser, the fabricated vertical-cavity surface-emitting laser having excellent performance and a relatively long cavity length.

[0024] 3. The application of the coupled-cavity vertical-cavity surface-emitting laser involved in this invention has a wide range of applications. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a coupled-cavity vertical-cavity surface-emitting laser.

[0026] Figure 2 This is a schematic diagram of the refractive index distribution and electric field distribution of the coupled-cavity vertical-cavity surface-emitting laser 1 in Example 1.

[0027] Figure 3 This is a schematic diagram of the full width at half maximum (FWHM) of the cold cavity reflection spectrum of the coupled-cavity vertical-cavity surface-emitting laser 1 in Example 1.

[0028] Figure description: 1-First electrode, 2-First Bragg mirror group, 3-Oxide layer, 4-Active region, 5-Second Bragg mirror group, 6-Second electrode, 7-Passive cavity, 8-Third Bragg mirror group, 9-Substrate.

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0030] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Detailed Implementation

[0031] Please see Figure 1 A coupled-cavity vertical-cavity surface-emitting laser (VCSEL) comprises, from top to bottom, a first Bragg mirror group, an oxide layer, an active region, a second Bragg mirror group, a passive cavity, a third Bragg mirror group, and a substrate. A first electrode is disposed on the side of the first Bragg mirror group away from the oxide layer. Second electrodes are disposed at both ends of the passive cavity on the side closest to the second Bragg mirror group. The reflectivity of the first Bragg mirror group is 99.3%–99.6%, the reflectivity of the second Bragg mirror group is 70%–85%, and the reflectivity of the third Bragg mirror group is 99.9%.

[0032] Understandably, the laser of this invention is equipped with three sets of Bragg reflectors and a passive cavity is introduced. The reflectivity of the three sets of Bragg reflectors is set with different parameters. The reflectivity of the bottom third Bragg reflector is limited to 99.9%; the reflectivity of the middle second Bragg reflector is limited to between 70% and 85%; and the reflectivity of the top first Bragg reflector is limited to between 99.3% and 99.6%. This allows photons to circulate repeatedly within the passive cavity between the bottom and middle Bragg reflector sets. The optical field within the passive cavity is higher than that in the active region, increasing the lifetime of photons within the cavity. As a result, the linewidth can reach less than 20MHz, which is more than two orders of magnitude smaller than the linewidth of a conventional vertical-cavity surface-emitting laser.

[0033] Meanwhile, because the present invention has a three-mirror cavity structure, the effective coupling cavity length of the laser is increased to about 8 μm, and the cold cavity linewidth Δλc can reach 0.01397 nm.

[0034] To further explain the principle, the Schawlow-Townes laser linewidth formula (see figure below) shows that reducing the cold cavity linewidth can reduce the laser linewidth. Since the cold cavity linewidth can be considered the derivative of the photon lifetime, increasing the intracavity photon lifetime can effectively reduce the laser linewidth. Spectral linewidth can be used to represent the spectral purity or coherence of a laser; it is the wavelength interval between two points on the spectral line where the amplitude of the peak wavelength of the principal longitudinal mode drops by half under standard operating conditions. The spectral linewidth of a laser mainly originates from phase fluctuations, including phase changes caused by the laser's own vibrations, external noise, and quantum fluctuations, primarily due to phase fluctuations caused by spontaneous emission. Above the threshold, the laser action is relatively stable, the optical field fluctuations are stable, and therefore the spontaneous emission rate is also relatively stable. Compared to traditional VCSELs, the photon lifetime in a coupled-cavity VCSEL increases, thus reducing the "cold cavity" linewidth. Since the laser linewidth is proportional to the square of the cold cavity linewidth, the reduction in the cold cavity linewidth caused by the passive cavity will result in a quadratic decrease in the laser linewidth.

[0035] Δv=(hv / P0)(v / λ) 2 (πη0n sp )(Δλ c ) 2 (1+α 2 )

[0036] Schawlow-Townes laser linewidth formula

[0037] This invention increases the intracavity lifetime of photons and results in a narrower linewidth by setting up three Bragg mirror groups and defining their specific reflectivity. Simultaneously, it introduces a passive cavity, enabling an effective cavity length of 8 μm and achieving a MHz level of less than 20 MHz. This solves the problem in existing technologies where vertical-cavity surface-emitting lasers (VCSELs) have short cavity lengths and large spectral linewidths, making it difficult to meet the narrow linewidth application requirements of VCSELs.

[0038] Furthermore, the passive cavity inside the laser in this invention can maintain modal purity and prevent all modes except the single longitudinal mode from lasing, thus making the laser perform better.

[0039] It should be noted that the coupled-cavity vertical-cavity surface-emitting laser of the present invention is an intracavity contact. For example, in some embodiments of the present invention, the middle second Bragg reflector group comprises three parts (upper part, middle part, and lower part), each part having different doping.

[0040] The second electrode contacts the lower part of the second Bragg reflector group. Since the lower part of the second Bragg reflector is undoped or lightly doped, current flows through the middle part, upper part, active region, and the top of the first Bragg reflector group of the second Bragg reflector group, achieving intra-cavity contact. This intra-cavity contact design reduces the resistance of the second Bragg reflector group, thereby improving the overall efficiency of the coupled-cavity vertical-cavity surface-emitting laser. The top first Bragg reflector group can adopt a similar intra-cavity contact design to improve the laser's efficiency.

[0041] It should be further noted that the middle part of the second Bragg reflector group is a single-component doped layer. The thickness of this single-component layer requires a sufficiently large etching force to be etched through. Therefore, in the specific etching process, this single-component doped layer in the middle cannot be etched through.

[0042] In some embodiments of the present invention, the first Bragg mirror group comprises 18 to 25 pairs of p-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 2×10 18 cm -3 ~3×10 18 cm -3 .

[0043] Specifically, the first Bragg mirror group includes 20 pairs of p-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 2.5 × 10⁻⁶ 18 cm -3 .

[0044] In some embodiments of the present invention, the second Bragg mirror group comprises a three-layer structure from bottom to top, all of which are n-type doped.

[0045] In some embodiments of the present invention, the three-layer structure includes a bottom layer, a middle layer, and a top layer from bottom to top, wherein the bottom layer consists of 8 to 12 pairs of Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 0.5 × 10⁻⁶ 18 cm -3～ 1.5×10 18 cm -3 The intermediate layer is Al. 0.16 Ga 0.84 As layer, doped at a concentration of 1×10⁻⁶ 18 cm-3 ~2×10 18 cm -3 The top layer consists of 6 to 8 pairs of Al 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.5 × 10⁻⁶ 18 cm -3 ~2×10 18 cm -3 .

[0046] Specifically, the three-layer structure includes a bottom layer, a middle layer, and a top layer from bottom to top, wherein the bottom layer consists of 10 pairs of Al 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.0 × 10⁻⁶ 18 cm -3 The intermediate layer is Al. 0.16 Ga 0.84 The As layer has a doping concentration of 1.5 × 10⁻⁶. 18 cm -3 The top layer consists of 7 pairs of Al 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.8 × 10⁻⁶ 18 cm -3 .

[0047] In some embodiments of the present invention, the thickness of the intermediate layer is 0.8 to 1.2 μm.

[0048] In some embodiments of the present invention, the third Bragg mirror group comprises 34 to 38 pairs of n-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.5 × 10⁻⁶ 18 cm -3 ~2×10 18 cm -3 .

[0049] Specifically, the third Bragg mirror group comprises 35 pairs of n-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.8 × 10⁻⁶ 18 cm -3 .

[0050] It should be noted that in some embodiments, the second Bragg mirror group is n-type doped and the first Bragg mirror group is p-type doped; in other embodiments, both the first and second Bragg mirror groups are p-type doped.

[0051] However, this type of vertical cavity surface-emitting laser has a significant drawback: due to the low mobility of p-type carriers, a relatively long lateral distance must be moved in the second Bragg mirror group. This low mobility leads to an increase in the overall resistance of the coupled cavity vertical cavity surface-emitting laser, resulting in a decrease in efficiency.

[0052] It should be noted that although the first, second, and third Bragg mirror groups can be formed by a step change between high and low refractive indices in the refractive index layer, this is not necessary. For example, the bottom third Bragg mirror group and the top first Bragg mirror group can be composed of parabolic components, which can alter carrier transport.

[0053] Specifically, if a graded layer is added between each pair of Bragg mirrors with high and low refractive indices, and the graded layer is Al... x Ga 1-x As, Al x Ga 1-x The As composition varies from x = 0.9 to 0.12; the thickness of the gradient layer is 10 to 20 nm. The series connection between adjacent P-type / N-type Bragg reflectors creates series resistance. By using a gradient layer, the resistance between adjacent P-type and / or N-type Bragg reflectors can be reduced. This improves the overall efficiency of the coupled-cavity vertical-cavity surface-emitting laser (VCSEL) when the driving current must pass through the middle second Bragg reflector group and / or the top first Bragg reflector group.

[0054] It should be further noted that in the coupled-cavity vertical-cavity surface-emitting laser of the present invention, the semiconductor materials used to form each of the first Bragg mirror group, the second Bragg mirror group, the active region, the passive cavity, and the third Bragg mirror group are substantially lattice-matched. The first Bragg mirror group, the second Bragg mirror group, the active region, and the third Bragg mirror group can be composed of various Il-VI or III-V semiconductor materials.

[0055] The active region, when excited by an electric current, can be used to generate a laser beam. The materials of the active region include at least one of GaP, GaAs, AlGaAs, InGaAs, InGaAsP, InAlGaAs, AlGaAsSb, GaN, AlSb, AlN, AlGaN, AlAs, InP, GaSb, InAs, InSb, HgTe, HgSe, ZnTe, CdS, ZnSe, ZnS, ZnO, Ga2O3, III-V, and II-VI materials.

[0056] In some embodiments of the present invention, the passive cavity is Al. 0.16 Ga 0.84 As, doping concentration is 0.5 × 10⁻⁶ 18 cm -3 ~1.5×10 18 cm -3 .

[0057] Specifically, the passive cavity is Al 0.16 Ga 0.84 As, doping concentration is 1.0 × 10⁻⁶ 18 cm -3 .

[0058] In some embodiments of the present invention, the thickness of the passive cavity is 1.5 to 2.25 μm.

[0059] Specifically, the thickness of the passive cavity is 2 μm.

[0060] It should be noted that although the third Bragg reflector group and the passive cavity in this embodiment of the invention use semiconductor materials, this is not mandatory. The passive cavity can also be made of materials with lower optical loss or lower temperature sensitivity. For example, these materials include various dielectric materials such as SiO2, Si3N4, TiO2, Ta2O5, etc.

[0061] In some embodiments of the present invention, the substrate is a GaAs substrate.

[0062] In some embodiments of the present invention, the first electrode and / or the second electrode are made of any one of gold, copper, graphite, silver or tin.

[0063] It is understood that, through the aforementioned three-layer structure and by adjusting the materials, doping concentration, and thickness of each layer, the present invention achieves a reflectivity of 99.3%–99.6% for the first Bragg reflector group, 70%–85% for the second Bragg reflector group, and 99.9% for the third Bragg reflector group. This allows photons to repeatedly circulate within the passive cavity between the bottom and middle Bragg reflector groups. The optical field within the passive cavity is higher than that in the active region, increasing the photon lifetime within the cavity. Consequently, the linewidth can reach a level of less than 20 MHz, resulting in excellent laser performance.

[0064] This invention also provides a method for fabricating a coupled-cavity vertical-cavity surface-emitting laser, comprising the following steps:

[0065] S1. Epitaxially grow a third Bragg mirror group, a passive cavity, a second Bragg mirror group, an active region, an oxide layer, and a first Bragg mirror group on a substrate in sequence to obtain a first preform.

[0066] S2. A first electrode is disposed on the first Bragg reflector group of the first preform, and a second electrode is disposed on the passive cavity of the first preform to complete the fabrication of the laser.

[0067] It should be noted that in the specific epitaxial process, there are buffer layers between the layers already involved, including the third Bragg mirror group, the passive cavity, the second Bragg mirror group, the active region, the oxide layer, and the first Bragg mirror group. The parameters are adjusted according to the actual fabrication requirements to perform epitaxy on each buffer layer to meet the actual needs.

[0068] It is understood that the coupled-cavity vertical-cavity surface-emitting laser and its fabrication method involved in this invention are applicable to a variety of material systems, making the structural design of the device more flexible.

[0069] This invention achieves superior laser performance by sequentially epitaxially extending layers onto a substrate and adjusting the material, doping concentration, and thickness of each layer. This results in a reflectivity of 99.3%–99.6% for the first Bragg mirror group, 70%–85% for the second Bragg mirror group, and 99.9% for the third Bragg mirror group.

[0070] In some embodiments of the present invention, the preparation method of the present invention may use metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) to epitaxially grow each layer.

[0071] The preferred preparation method of the present invention is to use metal-organic chemical vapor deposition (MOCVD) to epitaxially deposit each layer.

[0072] The present invention also provides an application of a coupled-cavity vertical-cavity surface-emitting laser prepared by the above-described method or by the above-described method.

[0073] The laser fabricated in this invention achieves an output spectral linewidth of less than 20 MHz, which is more than two orders of magnitude smaller than that of traditional vertical-cavity surface-emitting lasers, demonstrating significant advantages and thus offering greater application potential. It can be applied in specialized fields such as atomic clocks, demonstrating its superior capabilities.

[0074] Example 1

[0075] A coupled-cavity vertical-cavity surface-emitting laser 1, from top to bottom, includes a first Bragg mirror group, an oxide layer, an active region, a second Bragg mirror group, a passive cavity, a third Bragg mirror group, and a substrate. A first electrode is disposed on the side of the first Bragg mirror group away from the oxide layer, and second electrodes are disposed at both ends of the passive cavity on the side closer to the second Bragg mirror group. The reflectivity of the first Bragg mirror group is 99.3%–99.6%, the reflectivity of the second Bragg mirror group is 70%–85%, and the reflectivity of the third Bragg mirror group is 99.9%.

[0076] The first Bragg mirror group in this embodiment includes 24 pairs of p-type doped mirrors.

[0077] Al 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 2.5 × 10⁻⁶ 18 cm -3 .

[0078] The bottom layer of the second Bragg reflector group in this embodiment consists of 8 pairs of Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 0.5 × 10⁻⁶ 18 cm -3 The intermediate layer is Al. 0.16 Ga 0.84 The As layer has a doping concentration of 1.5 × 10⁻⁶. 18 cm -3 The top layer consists of 6 pairs of Al 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.5 × 10⁻⁶ 18 cm -3 .

[0079] The third Bragg mirror group in this embodiment includes 34 pairs of n-type doped Al.0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.8 × 10⁻⁶ 18 cm -3 .

[0080] The passive cavity in this embodiment is Al. 0.16 Ga 0.84 As, doping concentration is 0.8 × 10⁻⁶ 18 cm -3 .

[0081] The thickness of the passive cavity in this embodiment is 1.5 μm.

[0082] The fabrication method of this coupled-cavity vertical-cavity surface-emitting laser 1 is as follows:

[0083] S1. Epitaxially grow a third Bragg mirror group, a passive cavity, a second Bragg mirror group, an active region, an oxide layer, and a first Bragg mirror group on a substrate in sequence to obtain a first preform.

[0084] S2. A first electrode is set on the first Bragg reflector group of the first preform, and a second electrode is set on the passive cavity of the first preform to complete the fabrication of the coupled cavity vertical cavity surface-emitting laser 1.

[0085] During the fabrication process, the structure, material, and thickness of each layer of the coupled cavity vertical cavity surface-emitting laser are controlled to meet the above parameters, so that the reflectivity of the first Bragg reflector group is 99.3% to 99.6%, the reflectivity of the second Bragg reflector group is 70% to 85%, and the reflectivity of the third Bragg reflector group is 99.9%.

[0086] Example 2

[0087] A coupled-cavity vertical-cavity surface-emitting laser 2, whose structure is the same as that of Embodiment 1 and will not be described again, differs in that:

[0088] The first Bragg mirror group in this embodiment includes 25 pairs of p-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 2.1 × 10⁻⁶ 18 cm -3 .

[0089] The bottom layer of the second Bragg reflector group in this embodiment consists of 10 pairs of Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 0.58 × 10⁻⁶18 cm -3 The intermediate layer is Al. 0.16 Ga 0.84 The As layer has a doping concentration of 1.5 × 10⁻⁶. 18 cm -3 The top layer consists of 7 pairs of Al 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.5 × 10⁻⁶ 18 cm -3 .

[0090] The third Bragg mirror group in this embodiment includes 35 pairs of n-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 2×10 18 cm -3 .

[0091] The passive cavity in this embodiment is Al. 0.16 Ga 0.84 As, doping concentration is 0.8 × 10⁻⁶ 18 cm -3 .

[0092] The thickness of the passive cavity in this embodiment is 1.8 μm.

[0093] The fabrication method of this coupled-cavity vertical-cavity surface-emitting laser 2 is as follows:

[0094] S1. Epitaxially grow a third Bragg mirror group, a passive cavity, a second Bragg mirror group, an active region, an oxide layer, and a first Bragg mirror group on a substrate in sequence to obtain a first preform.

[0095] S2. A first electrode is set on the first Bragg reflector group of the first preform, and a second electrode is set on the passive cavity of the first preform to complete the fabrication of the coupled cavity vertical cavity surface-emitting laser 2.

[0096] During the fabrication process, the structure, material, and thickness of each layer of the coupled cavity vertical cavity surface-emitting laser are controlled to meet the above parameters, so that the reflectivity of the first Bragg reflector group is 99.3% to 99.6%, the reflectivity of the second Bragg reflector group is 70% to 85%, and the reflectivity of the third Bragg reflector group is 99.9%.

[0097] Example 3

[0098] A coupled-cavity vertical-cavity surface-emitting laser 3, whose structure is the same as that of Embodiment 1 and will not be described again, differs in that:

[0099] The first Bragg mirror group in this embodiment includes 23 pairs of p-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 2.5 × 10⁻⁶ 18 cm -3 .

[0100] The bottom layer of the second Bragg reflector group in this embodiment consists of 10 pairs of Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 0.58 × 10⁻⁶ 18 cm -3 The intermediate layer is Al. 0.16 Ga 0.84 The As layer has a doping concentration of 1.5 × 10⁻⁶. 18 cm -3 The top layer consists of 7 pairs of Al 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.5 × 10⁻⁶ 18 cm -3 .

[0101] The third Bragg mirror group in this embodiment includes 35 pairs of n-type doped mirrors.

[0102] Al 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.5 × 10⁻⁶ 18 cm -3 .

[0103] The passive cavity in this embodiment is Al. 0.16 Ga 0.84 As, doping concentration is 0.8 × 10⁻⁶ 18 cm -3 .

[0104] The thickness of the passive cavity in this embodiment is 2μm.

[0105] The fabrication method of this coupled-cavity vertical-cavity surface-emitting laser 3 is as follows:

[0106] S1. Epitaxially grow a third Bragg mirror group, a passive cavity, a second Bragg mirror group, an active region, an oxide layer, and a first Bragg mirror group on a substrate in sequence to obtain a first preform.

[0107] S2. A first electrode is set on the first Bragg reflector group of the first preform, and a second electrode is set on the passive cavity of the first preform to complete the fabrication of the coupled cavity vertical cavity surface-emitting laser 3.

[0108] During the fabrication process, the structure, material, and thickness of each layer of the coupled cavity vertical cavity surface-emitting laser are controlled to meet the above parameters, so that the reflectivity of the first Bragg reflector group is 99.3% to 99.6%, the reflectivity of the second Bragg reflector group is 70% to 85%, and the reflectivity of the third Bragg reflector group is 99.9%.

[0109] Example 4

[0110] A coupled-cavity vertical-cavity surface-emitting laser 4, whose structure is the same as that of Embodiment 1 and will not be described again, differs in that:

[0111] The first Bragg mirror group in this embodiment includes 25 pairs of p-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 2.9 × 10⁻⁶ 18 cm -3 .

[0112] The bottom layer of the second Bragg reflector group in this embodiment consists of 9 pairs of Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.2 × 10⁻⁶ 18 cm -3 The intermediate layer is Al. 0.16 Ga 0.84 As layer, doping concentration is 2×10⁻⁶ 18 cm -3 The top layer consists of 6 pairs of Al 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.8 × 10⁻⁶ 18 cm -3 .

[0113] The third Bragg mirror group in this embodiment includes 36 pairs of n-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.8 × 10⁻⁶ 18 cm -3 .

[0114] The passive cavity in this embodiment is Al. 0.16 Ga0.84 As, doping concentration is 1.1 × 10⁻⁶ 18 cm -3 .

[0115] The thickness of the passive cavity in this embodiment is 1.9 μm.

[0116] The fabrication method of this coupled-cavity vertical-cavity surface-emitting laser 4 is as follows:

[0117] S1. Epitaxially grow a third Bragg mirror group, a passive cavity, a second Bragg mirror group, an active region, an oxide layer, and a first Bragg mirror group on a substrate in sequence to obtain a first preform.

[0118] S2. A first electrode is set on the first Bragg reflector group of the first preform, and a second electrode is set on the passive cavity of the first preform to complete the fabrication of the coupled cavity vertical cavity surface-emitting laser 4.

[0119] During the fabrication process, the structure, material, and thickness of each layer of the coupled cavity vertical cavity surface-emitting laser are controlled to meet the above parameters, so that the reflectivity of the first Bragg reflector group is 99.3% to 99.6%, the reflectivity of the second Bragg reflector group is 70% to 85%, and the reflectivity of the third Bragg reflector group is 99.9%.

[0120] Example 5

[0121] A coupled-cavity vertical-cavity surface-emitting laser 5, whose structure is the same as that of Embodiment 1 and will not be described again, differs in that:

[0122] The first Bragg mirror group in this embodiment includes 21 pairs of p-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 2×10 18 cm -3 .

[0123] The bottom layer of the second Bragg reflector group in this embodiment consists of 11 pairs of Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.3 × 10⁻⁶ 18 cm -3 The intermediate layer is Al. 0.16 Ga 0.84 The As layer has a doping concentration of 1.3 × 10⁻⁶. 18 cm -3 The top layer consists of 8 pairs of Al 0.92 Ga 0.08 As / Al 0.16 Ga0.84 As, doping concentration is 1.6 × 10⁻⁶ 18 cm -3 .

[0124] The third Bragg mirror group in this embodiment includes 35 pairs of n-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.8 × 10⁻⁶ 18 cm -3 .

[0125] The passive cavity in this embodiment is Al. 0.16 Ga 0.84 As, doping concentration is 1.1 × 10⁻⁶ 18 cm -3 .

[0126] The thickness of the passive cavity in this embodiment is 2.05 μm.

[0127] The fabrication method of this coupled-cavity vertical-cavity surface-emitting laser 5 is as follows:

[0128] S1. Epitaxially grow a third Bragg mirror group, a passive cavity, a second Bragg mirror group, an active region, an oxide layer, and a first Bragg mirror group on a substrate in sequence to obtain a first preform.

[0129] S2. A first electrode is set on the first Bragg reflector group of the first preform, and a second electrode is set on the passive cavity of the first preform to complete the fabrication of the coupled cavity vertical cavity surface-emitting laser 5.

[0130] During the fabrication process, the structure, material, and thickness of each layer of the coupled cavity vertical cavity surface-emitting laser are controlled to meet the above parameters, so that the reflectivity of the first Bragg reflector group is 99.3% to 99.6%, the reflectivity of the second Bragg reflector group is 70% to 85%, and the reflectivity of the third Bragg reflector group is 99.9%.

[0131] Example 6

[0132] A coupled-cavity vertical-cavity surface-emitting laser 6, whose structure is the same as that of Embodiment 1 and will not be described again, differs in that:

[0133] The first Bragg mirror group in this embodiment includes 24 pairs of p-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 2.55 × 10⁻⁶ 18 cm -3 .

[0134] The bottom layer of the second Bragg reflector group in this embodiment consists of 8 pairs of Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 0.5 × 10⁻⁶ 18 cm -3 The intermediate layer is Al. 0.16 Ga 0.84 The As layer has a doping concentration of 1.5 × 10⁻⁶. 18 cm -3 The top layer consists of 6 pairs of Al 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.5 × 10⁻⁶ 18 cm -3 .

[0135] The third Bragg mirror group in this embodiment includes 35 pairs of n-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.8 × 10⁻⁶ 18 cm -3 .

[0136] The passive cavity in this embodiment is Al. 0.16 Ga 0.84 As, doping concentration is 0.8 × 10⁻⁶ 18 cm -3 .

[0137] The thickness of the passive cavity in this embodiment is 2.2 μm.

[0138] The fabrication method of this coupled-cavity vertical-cavity surface-emitting laser 6 is as follows:

[0139] S1. Epitaxially grow a third Bragg mirror group, a passive cavity, a second Bragg mirror group, an active region, an oxide layer, and a first Bragg mirror group on a substrate in sequence to obtain a first preform.

[0140] S2. A first electrode is set on the first Bragg reflector group of the first preform, and a second electrode is set on the passive cavity of the first preform to complete the fabrication of the coupled cavity vertical cavity surface-emitting laser 6.

[0141] During the fabrication process, the structure, material, and thickness of each layer of the coupled cavity vertical cavity surface-emitting laser are controlled to meet the above parameters, so that the reflectivity of the first Bragg reflector group is 99.3% to 99.6%, the reflectivity of the second Bragg reflector group is 70% to 85%, and the reflectivity of the third Bragg reflector group is 99.9%.

[0142] Example 7

[0143] A coupled-cavity vertical-cavity surface-emitting laser 7, whose structure is the same as that of Embodiment 1 and will not be described again, differs in that:

[0144] The first Bragg mirror group in this embodiment includes 24 pairs of p-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 2.9 × 10⁻⁶ 18 cm -3 .

[0145] The bottom layer of the second Bragg reflector group in this embodiment consists of 10 pairs of Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 0.58 × 10⁻⁶ 18 cm -3 The intermediate layer is Al. 0.16 Ga 0.84 The As layer has a doping concentration of 1.5 × 10⁻⁶. 18 cm -3 The top layer consists of 8 pairs of Al 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.5 × 10⁻⁶ 18 cm -3 .

[0146] The third Bragg mirror group in this embodiment includes 36 pairs of n-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.9 × 10⁻⁶ 18 cm -3 .

[0147] The passive cavity in this embodiment is Al. 0.16 Ga 0.84 As, doping concentration is 0.8 × 10⁻⁶ 18 cm -3 .

[0148] The thickness of the passive cavity in this embodiment is 2.25 μm.

[0149] The fabrication method of this coupled-cavity vertical-cavity surface-emitting laser 7 is as follows:

[0150] S1. Epitaxially grow a third Bragg mirror group, a passive cavity, a second Bragg mirror group, an active region, an oxide layer, and a first Bragg mirror group on a substrate in sequence to obtain a first preform.

[0151] S2. A first electrode is set on the first Bragg reflector group of the first preform, and a second electrode is set on the passive cavity of the first preform to complete the fabrication of the coupled cavity vertical cavity surface-emitting laser 7.

[0152] During the fabrication process, the structure, material, and thickness of each layer of the coupled cavity vertical cavity surface-emitting laser are controlled to meet the above parameters, so that the reflectivity of the first Bragg reflector group is 99.3% to 99.6%, the reflectivity of the second Bragg reflector group is 70% to 85%, and the reflectivity of the third Bragg reflector group is 99.9%.

[0153] Example 8

[0154] A coupled-cavity vertical-cavity surface-emitting laser 8, whose structure is the same as that of Embodiment 1 and will not be described again, differs in that:

[0155] The first Bragg mirror group in this embodiment includes 24 pairs of p-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 2.9 × 10⁻⁶ 18 cm -3 .

[0156] The bottom layer of the second Bragg reflector group in this embodiment consists of 9 pairs of Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 0.5 × 10⁻⁶ 18 cm -3 The intermediate layer is Al. 0.16 Ga 0.84 The As layer has a doping concentration of 1.5 × 10⁻⁶. 18 cm -3 The top layer consists of 8 pairs of Al 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.9 × 10⁻⁶ 18 cm -3 .

[0157] The third Bragg mirror group in this embodiment includes 38 pairs of n-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84As, doping concentration is 2.0 × 10⁻⁶ 18 cm -3 .

[0158] The passive cavity in this embodiment is Al. 0.16 Ga 0.84 As, doping concentration is 1.2 × 10⁻⁶ 18 cm -3 .

[0159] The thickness of the passive cavity in this embodiment is 2.15 μm.

[0160] The fabrication method of this coupled-cavity vertical-cavity surface-emitting laser 8 is as follows:

[0161] S1. Epitaxially grow a third Bragg mirror group, a passive cavity, a second Bragg mirror group, an active region, an oxide layer, and a first Bragg mirror group on a substrate in sequence to obtain a first preform.

[0162] S2. A first electrode is set on the first Bragg reflector group of the first preform, and a second electrode is set on the passive cavity of the first preform to complete the fabrication of the coupled cavity vertical cavity surface-emitting laser 8.

[0163] During the fabrication process, the structure, material, and thickness of each layer of the coupled cavity vertical cavity surface-emitting laser are controlled to meet the above parameters, so that the reflectivity of the first Bragg reflector group is 99.3% to 99.6%, the reflectivity of the second Bragg reflector group is 70% to 85%, and the reflectivity of the third Bragg reflector group is 99.9%.

[0164] Example 9

[0165] A coupled-cavity vertical-cavity surface-emitting laser 9, whose structure is the same as that of Embodiment 1 and will not be described again, differs in that:

[0166] The first Bragg mirror group in this embodiment includes 24 pairs of p-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 2×10 18 cm -3 .

[0167] The bottom layer of the second Bragg reflector group in this embodiment consists of 11 pairs of Al. 0.92 Ga 0.08 As /

[0168] Al 0.16 Ga 0.84 As, doping concentration is 1.3 × 10⁻⁶ 18 cm -3 The intermediate layer is Al.0.16 Ga 0.84 The As layer has a doping concentration of 1.9 × 10⁻⁶. 18 cm -3 The top layer consists of 7 pairs of Al 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 2×10 18 cm -3 .

[0169] The third Bragg mirror group in this embodiment includes 36 pairs of n-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.9 × 10⁻⁶ 18 cm -3 .

[0170] The passive cavity in this embodiment is Al. 0.16 Ga 0.84 As, doping concentration is 1.1 × 10⁻⁶ 18 cm -3 .

[0171] The thickness of the passive cavity in this embodiment is 1.98 μm.

[0172] The fabrication method of this coupled-cavity vertical-cavity surface-emitting laser 9 is as follows:

[0173] S1. Epitaxially grow a third Bragg mirror group, a passive cavity, a second Bragg mirror group, an active region, an oxide layer, and a first Bragg mirror group on a substrate in sequence to obtain a first preform.

[0174] S2. A first electrode is set on the first Bragg reflector group of the first preform, and a second electrode is set on the passive cavity of the first preform to complete the fabrication of the coupled cavity vertical cavity surface-emitting laser 9.

[0175] During the fabrication process, the structure, material, and thickness of each layer of the coupled cavity vertical cavity surface-emitting laser are controlled to meet the above parameters, so that the reflectivity of the first Bragg reflector group is 99.3% to 99.6%, the reflectivity of the second Bragg reflector group is 70% to 85%, and the reflectivity of the third Bragg reflector group is 99.9%.

[0176] Example 10

[0177] A coupled-cavity vertical-cavity surface-emitting laser 10, whose structure is the same as that of Embodiment 1 and will not be described again, differs in that:

[0178] The first Bragg mirror group in this embodiment includes 18 pairs of p-type doped Al.0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 2×10 18 cm -3 .

[0179] The bottom layer of the second Bragg reflector group in this embodiment consists of 9 pairs of Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 0.58 × 10⁻⁶ 18 cm -3 The intermediate layer is Al. 0.16 Ga 0.84 The As layer has a doping concentration of 1.5 × 10⁻⁶. 18 cm -3 The top layer consists of 6 pairs of Al 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.5 × 10⁻⁶ 18 cm -3 .

[0180] The third Bragg mirror group in this embodiment includes 34 pairs of n-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.5 × 10⁻⁶ 18 cm -3 .

[0181] The passive cavity in this embodiment is Al. 0.16 Ga 0.84 As, doping concentration is 0.95 × 10⁻⁶ 18 cm -3 .

[0182] The thickness of the passive cavity in this embodiment is 2.14 μm.

[0183] The fabrication method of this coupled-cavity vertical-cavity surface-emitting laser 10 is as follows:

[0184] S1. Epitaxially grow a third Bragg mirror group, a passive cavity, a second Bragg mirror group, an active region, an oxide layer, and a first Bragg mirror group on a substrate in sequence to obtain a first preform.

[0185] S2. A first electrode is set on the first Bragg reflector group of the first preform, and a second electrode is set on the passive cavity of the first preform to complete the fabrication of the coupled cavity vertical cavity surface-emitting laser 10.

[0186] During the fabrication process, the structure, material, and thickness of each layer of the coupled cavity vertical cavity surface-emitting laser are controlled to meet the above parameters, so that the reflectivity of the first Bragg reflector group is 99.3% to 99.6%, the reflectivity of the second Bragg reflector group is 70% to 85%, and the reflectivity of the third Bragg reflector group is 99.9%.

[0187] Experimental Example 1. Refractive index distribution and electric field distribution of the coupled-cavity vertical-cavity surface-emitting laser of the present invention 1.1 Experimental Design

[0188] The coupled-cavity vertical-cavity surface-emitting laser 1 described in Example 1 was selected, and its refractive index distribution and electric field distribution were analyzed. The analysis results are shown in […]. Figure 2 , Figure 3 .

[0189] 1.2 Results Analysis

[0190] See Figure 2 and Figure 3 The image shows a simulated optical field profile near the active region of the coupled-cavity vertical-cavity surface-emitting laser 1. The thin lines represent the true refractive index, and the thick lines represent the resonant cavity standing waves. It can be seen that the coupled-cavity vertical-cavity surface-emitting laser 1 described in Example 1 is designed to achieve a narrow linewidth at 894.6 nm. Below the quantum well active region, there is an Al layer with a thickness of approximately 2 μm. 0.16 Ga 0.84 As a passive cavity, the overall effective coupling cavity length of a VCSEL is 8 μm. For ordinary VCSEL lasers, the cold cavity linewidth Δλc is generally greater than 0.2 nm. For VCSEL lasers with an output optical power of less than 1 mW, the output spectral linewidth can reach over 1 GHz.

[0191] See Figure 3 As shown, for narrow-linewidth VCSELs with coupled cavities, the cold cavity linewidth of the resonant cavity can reach below 0.01 nm due to the increased photon cycle lifetime within the cavity. With an output optical power of 1 mW, when the Δλc of the all-semiconductor coupled-cavity VCSEL is 0.01397 nm, theoretical calculations show that the laser output spectral linewidth can reach approximately 0.4 MHz, which is more than two orders of magnitude smaller than the linewidth of traditional VCSELs.

[0192] In summary, the coupled-cavity vertical-cavity surface-emitting laser (VCSEL) of this invention employs three sets of Bragg mirrors and introduces a passive cavity. The reflectivity of the three sets of Bragg mirrors is set with different parameters: the reflectivity of the bottom third Bragg mirror set is limited to 99.9%; the reflectivity of the middle second Bragg mirror set is limited to between 70% and 85%; and the reflectivity of the top first Bragg mirror set is limited to between 99.3% and 99.6%. This allows photons to repeatedly circulate within the passive cavity between the bottom and middle Bragg mirror sets. The optical field within the passive cavity is higher than that in the active region, increasing the photon lifetime within the cavity. Consequently, the linewidth can reach less than 20 MHz, which is more than two orders of magnitude smaller than that of conventional VCSELs. It exhibits superior performance, a longer cavity length, and a wider range of applications. This invention solves the problem that existing VCSELs have short cavity lengths and large spectral linewidths, making it difficult to meet the narrow linewidth requirements of VCSEL applications.

[0193] The above embodiments are merely one implementation of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A coupled cavity vertical cavity surface emitting laser, characterized by, The laser, from top to bottom, includes a first Bragg mirror group, an oxide layer, an active region, a second Bragg mirror group, a passive cavity, a third Bragg mirror group, and a substrate. A first electrode is located on the side of the first Bragg mirror group away from the oxide layer. Second electrodes are located at both ends of the passive cavity on the side closest to the second Bragg mirror group. The reflectivity of the first Bragg mirror group is 99.3%–99.6%, the reflectivity of the second Bragg mirror group is 70%–85%, and the reflectivity of the third Bragg mirror group is 99.9%. The first Bragg mirror group includes 18–25 pairs of p-type doped Al atoms. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 2×10 18 cm -3 ~3×10 18 cm -3 The second Bragg mirror group consists of a three-layer structure, all of which are n-type doped, from bottom to top.

2. The coupled cavity vertical cavity surface emitting laser of claim 1, wherein, The three-layer structure, from bottom to top, includes a bottom layer, a middle layer, and a top layer. The bottom layer consists of 8 to 12 pairs of Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 0.5 × 10⁻⁶ 18 cm -3~ 1.5×10 18 cm -3 ; The intermediate layer is Al. 0.16 Ga 0.84 As layer, doped with a concentration of 1×10⁻⁶ 18 cm -3 ~2×10 18 cm -3 The top layer consists of 6-8 pairs of Al 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.5 × 10⁻⁶ 18 cm -3 ~2×10 18 cm -3 .

3. The coupled cavity vertical cavity surface emitting laser of claim 1, wherein, The third Bragg mirror group comprises 34-38 pairs of n-type doped Al. 0.92 Ga 0.08 As / Al 0.16 Ga 0.84 As, doping concentration is 1.5 × 10⁻⁶ 18 cm -3 ~2×10 18 cm -3 .

4. The coupled cavity vertical cavity surface emitting laser of claim 1, wherein, The passive cavity is Al 0.16 Ga 0.84 As with a doping concentration of 0.5 x 10 18 cm -3 ~1.5 x 10 18 cm -3 .

5. A coupled-cavity vertical-cavity surface-emitting laser according to claim 4, characterized in that, The thickness of the passive cavity is 1.5~2.25μm.

6. The coupled cavity vertical cavity surface emitting laser of claim 1, wherein, The substrate is a GaAs substrate.

7. A method of fabricating a coupled cavity vertical cavity surface emitting laser according to any one of claims 1 to 6, characterized in that Includes the following steps: S1. Epitaxially grow a third Bragg mirror group, a passive cavity, a second Bragg mirror group, an active region, an oxide layer, and a first Bragg mirror group on a substrate in sequence to obtain a first preform. S2. A first electrode is disposed on the first Bragg reflector group of the first preform, and a second electrode is disposed on the passive cavity of the first preform to complete the fabrication of the laser.

8. Application of a coupled-cavity vertical-cavity surface-emitting laser based on any one of claims 1 to 6 or prepared by claim 7.

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