Vertical cavity surface emitting laser
By introducing a phase change material layer into the optical resonant cavity of a VCSEL and using energy stimulation to adjust its phase state, the problem of controlling the optical cavity length of a VCSEL is solved, enabling flexible tuning of the lasing wavelength and improved performance consistency. This method is applicable to various VCSEL structures and simplifies the fabrication process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-20
- Publication Date
- 2026-04-14
AI Technical Summary
Existing technologies struggle to precisely control the optical cavity length of vertical cavity surface-emitting lasers (VCSELs), leading to decreased device performance consistency and difficulties in lasing wavelength tuning, particularly in high-resolution displays and precision light source applications.
By introducing a phase change material layer into the optical resonant cavity of a VCSEL, and applying energy through an excitation unit to induce a controllable phase transition, the optical cavity length can be adjusted, thereby achieving flexible tuning of the lasing wavelength and compensation for process errors.
It achieves flexible tuning of lasing wavelength and improved performance consistency, is applicable to various VCSEL structures, simplifies the fabrication process, and improves yield and device stability.
Smart Images
Figure CN121863185A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of semiconductor technology, and more specifically, to a vertical-cavity surface-emitting laser. Background Technology
[0002] Vertical-cavity surface-emitting lasers (VCSELs) are widely used in display, optical communication, and biomedical fields due to their advantages such as low threshold current, circular spot size, and ease of integration into two-dimensional arrays. The lasing wavelength and longitudinal mode characteristics of VCSELs are highly dependent on the effective cavity length of their optical resonator.
[0003] However, in actual fabrication, due to uncertainties in epitaxial growth thickness errors, deposition errors in distributed reflective structures (such as dielectric Bragg mirrors), and subsequent processes such as bonding and polishing, the optical cavity length of VCSELs is difficult to control precisely, easily leading to cavity mode shift, threshold elevation, or decreased device performance consistency. On the other hand, as the application requirements of VCSELs in high-resolution displays, precision light sources, and array devices continue to increase, it is not only required that the device possesses the target lasing wavelength after fabrication, but it is also desirable to be able to tune the lasing wavelength within a certain range to adapt to different application scenarios or compensate for the effects of environmental changes.
[0004] Existing technologies typically rely on precise thickness control during high-precision epitaxial growth and polishing to achieve cavity length adjustment. This process is complex, has limited adjustment flexibility, and struggles to simultaneously achieve tuning capability and fabrication error compensation. Therefore, it is necessary to propose a VCSEL device structure that is simple in structure, highly compatible with various processes, and capable of simultaneously achieving lasing wavelength tuning and wavelength deviation correction. Summary of the Invention
[0005] In view of this, the present disclosure provides a vertical cavity surface-emitting laser.
[0006] One aspect of this disclosure provides a vertical-cavity surface-emitting laser, comprising: an optical resonant cavity including an active layer for generating stimulated emission, and a first distributed Bragg mirror and a second distributed Bragg mirror located on opposite sides of the active layer; a phase change material layer disposed within the optical path of the optical resonant cavity; and an excitation unit coupled to the phase change material layer for applying energy stimulation to the phase change material layer; wherein the phase change material layer undergoes a controllable phase transition in response to the energy stimulation applied by the excitation unit, the phase transition causing a corresponding change in the refractive index of the phase change material layer to adjust the equivalent cavity length of the optical resonant cavity.
[0007] According to an embodiment of this disclosure, the phase change material layer is integrated on one side of the first distributed Bragg reflector.
[0008] According to embodiments of this disclosure, the material further includes: a first conductive layer disposed between the active layer and the first distributed reflector; a second conductive layer disposed between the active layer and the second distributed reflector, wherein the materials of the first conductive layer and the second conductive layer are N-type semiconductor material and P-type semiconductor material, respectively; a current limiting layer disposed on the side of the second conductive layer away from the active layer; a first electrode disposed on the first conductive layer; and a second electrode disposed on the side of the current limiting layer away from the second conductive layer. According to embodiments of this disclosure, the phase change material layer is made of an amorphous, crystalline, or metastable structure between an amorphous and crystalline state.
[0009] According to embodiments of this disclosure, the energy stimulus is any one of thermal energy, electrical energy, light energy, or electro-thermal coupling.
[0010] According to embodiments of this disclosure, the excitation unit is a micro heater structure disposed in the region adjacent to the phase change material layer, or an electrode structure connected to the phase change material layer.
[0011] Compared with the prior art, the vertical-cavity surface-emitting laser provided in this disclosure has the following advantages:
[0012] 1. By controlling the phase transition of the phase change material layer to change its refractive index, the equivalent optical path length of the optical resonant cavity can be controlled and adjusted, thereby enabling flexible tuning of the VCSEL lasing wavelength to meet the wavelength requirements of different application scenarios.
[0013] 2. After the device is fabricated, the deviation of the lasing wavelength can be corrected by adjusting the cavity length deviation caused by the phase state compensation process error of the phase change material, thereby improving the consistency of device performance and yield.
[0014] 3. The vertical cavity surface-emitting laser provided in this disclosure is not limited to a specific semiconductor material system or epitaxial structure, and is applicable to a variety of VCSEL structures, with strong versatility;
[0015] 4. The phase change material cavity tuning scheme is compatible with existing VCSEL fabrication processes, and the device structure is simple and easy to industrialize. Attached Figure Description
[0016] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:
[0017] Figure 1 A schematic diagram of a vertical cavity surface-emitting laser according to an embodiment of the present disclosure is shown.
[0018] Figure 2A The illustration schematically shows a diagram of applying energy stimulation to the phase change material layer according to an embodiment of the present disclosure;
[0019] Figure 2B This schematic diagram illustrates the current flow direction for applying energy stimulation to the phase change material layer according to an embodiment of the present disclosure;
[0020] Figure 3 The diagram illustrates another embodiment of the present disclosure of applying energy stimulation to the phase change material layer;
[0021] Figure 4 A schematic diagram of a vertical cavity surface-emitting laser according to another embodiment of the present disclosure is shown.
[0022] Explanation of reference numerals in the attached figures:
[0023] 1-First distributed Bragg reflector; 2-First electrode; 3-Phase change material layer; 4-First conductive layer; 5-Active layer; 6-Second conductive layer; 7-Current confinement layer; 8-Second electrode; 9-Second distributed Bragg reflector; 10-Metal bonding layer; 11-Heterogeneous substrate; 12-Micro heater structure; 13-Epiaxial structure; 14-Second electrode and metal bonding layer; 15-Substrate; 16-Electrode structure; 17-Electron blocking layer; 18-ITO layer. Detailed Implementation
[0024] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.
[0025] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.
[0026] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.
[0027] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).
[0028] This disclosure provides a vertical-cavity surface-emitting laser (VCSEL) including an active layer 5 for generating stimulated emission, a first distributed Bragg mirror 1 and a second distributed Bragg mirror 9 located on either side of the active layer 5, and a phase change material (PCM) layer 3. The PCM layer 3 is disposed within the optical path of the optical resonant cavity. An excitation unit coupled to the PCM layer 3 applies energy stimulation to the PCM layer 3. In response to the energy stimulation applied by the excitation unit, the PCM layer 3 undergoes a controllable phase transition. This phase transition causes a corresponding change in the refractive index of the PCM layer 3, thereby adjusting the equivalent cavity length of the optical resonant cavity and thus changing the equivalent optical path length of the optical resonant cavity.
[0029] Figure 1 A schematic diagram of a vertical cavity surface-emitting laser according to an embodiment of the present disclosure is shown.
[0030] like Figure 1 As shown in the embodiments of this application, the vertical-cavity surface-emitting laser further includes a first conductive layer 4, a second conductive layer 6, a current-limiting layer 7, a first electrode 2, and a second electrode 8. The first conductive layer 4 is disposed between the active layer 5 and the first distributed mirror; the second conductive layer 6 is disposed between the active layer 5 and the second distributed mirror. The materials of the first conductive layer 4 and the second conductive layer 6 are N-type semiconductor materials (such as N-type doped AlGaAs or GaN) and P-type semiconductor materials (such as P-type doped AlGaAs or GaN), respectively, forming a carrier injection structure together with the first conductive layer 4. The current-limiting layer 7 is disposed on the side of the second conductive layer 6 away from the active layer 5. This layer typically contains a high-aluminum composition layer, and an insulating oxide-limiting aperture is formed in the portion other than the central region through a selective oxidation process to localize the injected current in the central region, reduce the threshold current, and improve mode characteristics. The first electrode 2 is disposed on the first conductive layer 4; the second electrode 8 is disposed on the side of the current-limiting layer 7 away from the second conductive layer 6. In addition, the vertical cavity surface-emitting laser is bonded to the heterogeneous substrate 11 through a metal bonding layer 10.
[0031] In operation, a bias voltage is applied between the first electrode 2 and the second electrode 8. Current flows in from the second electrode 8, passes through each layer in sequence, and flows out from the first electrode 2, driving the active layer 5 to generate laser light.
[0032] In embodiments of this disclosure, the phase change material layer 3 is integrated on one side of the first distributed Bragg reflector 1. The excitation unit can be coupled to the phase change material layer 3; for example, the first electrode 2 contacts the phase change material layer 3, and the excitation unit achieves electrical connection or thermal coupling with the phase change material layer 3 through the first electrode 2. The excitation unit causes a localized, controllable phase transition (such as a reversible transition between crystalline and amorphous states) in the phase change material layer 3, thereby changing its refractive index. Since the phase change material layer 3 is located within the resonant cavity, the change in its refractive index directly modulates the equivalent optical length of the resonant cavity, ultimately achieving dynamic, non-volatile tuning of the laser's lasing wavelength or compensation for process deviations.
[0033] Optionally, the material of the phase change material layer 3 includes chalcogenide phase change materials, transition metal oxide phase change materials or modified materials thereof, and can be an amorphous, crystalline or metastable structure between amorphous and crystalline states, without limitation.
[0034] It should be noted that the energy stimulation of the phase change material layer 3 by the excitation unit can be any one of thermal energy, electrical energy, light energy, or electro-thermal coupling. The specific implementation of the excitation unit can be selected according to the activation mechanism of the phase change material and the device integration process.
[0035] Figure 2A This schematic diagram illustrates an application of energy stimulation to the phase change material layer 3 according to an embodiment of the present disclosure. Figure 2B The direction of the current under its operating conditions is shown.
[0036] like Figure 2A and Figure 2B As shown, in some embodiments of this disclosure, the excitation unit is a micro-heater structure 12 disposed in the vicinity of the phase change material layer 3. The phase change material is locally heated via the Joule heating effect, causing a phase transition in the phase change material layer 3. The phase change material does not participate in the current injection process; the optical cavity length is changed only by altering its refractive index.
[0037] exist Figure 2A In the middle, the extensional structure 13 includes Figure 1 The vertical-cavity surface-emitting laser shown includes all the components except for the first distributed Bragg reflector 1, the first electrode 2, and the second electrode 8. Component 14 includes the second electrode and a metal bonding layer. The entire structure is fabricated on a substrate 15.
[0038] Figure 3 The diagram illustrates another embodiment of the present disclosure of applying energy stimulation to the phase change material layer 3.
[0039] like Figure 3As shown, in some embodiments of this disclosure, the excitation unit is an electrode structure 16 connected to the phase change material layer 3, which triggers the phase transition of the phase change material layer 3 by applying voltage or current to it.
[0040] exist Figure 3 In the middle, the extensional structure 13 includes Figure 1 The vertical-cavity surface-emitting laser shown includes all the components except for the first distributed Bragg reflector 1, the first electrode 2, the 3-phase change material layer, and the second electrode 8. Electrode 14 includes the second electrode and a metal bonding layer. The entire structure is fabricated on a substrate 15.
[0041] By controlling the power, duration, or pulse parameters of the excitation unit, the phase state of the phase change material can be controlled in stages, thereby enabling coarse and fine adjustment of the optical cavity length.
[0042] Figure 4 A schematic diagram of a vertical cavity surface-emitting laser according to another embodiment of the present disclosure is shown.
[0043] like Figure 4 As shown in this embodiment, the vertical-cavity surface-emitting laser is a nitride semiconductor-based VCSEL. The first conductive layer 4 is an N-type gallium nitride conductive layer, and the second conductive layer 6 is a P-type gallium nitride conductive layer. An electron blocking layer 17 is provided between the active layer 5 and the second conductive layer 6. This layer is typically made of P-type AlGaN material, whose higher Al content creates a wider bandgap and a higher barrier. Its main function is to prevent holes injected from the P-region and electrons overflowing from the N-region from recombining more effectively within the active layer 5, preventing electron overflow into the P-region and causing efficiency loss and heat generation, thereby improving internal quantum efficiency and device performance. An ITO layer 18 is provided in the region of the current-limiting layer 7 that contacts the second electrode 8. This layer is used to uniformly extend the current from the central electrode laterally across the entire current-limiting aperture region, achieving uniform current injection and avoiding current congestion. The phase change material can be an antimony sulfide-based phase change material. This structure is only illustrative and is not limited to this embodiment; it is also applicable to VCSELs using other semiconductor material systems such as arsenides and phosphides.
[0044] The vertical-cavity surface-emitting laser provided in this embodiment effectively multiplexes the current injection path (for laser generation) and the phase-change excitation path in terms of physical structure and electrical signals, avoiding mutual interference and ensuring the stability and tuning reliability of the laser in operation. Simultaneously, this structure provides a feasible device foundation for the subsequent realization of electrically controlled, fast, and low-power wavelength-tunable VCSELs.
[0045] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.
Claims
1. A vertical-cavity surface-emitting laser, characterized in that, include: The optical resonant cavity includes an active layer (5) for generating stimulated emission and a first distributed Bragg mirror (1) and a second distributed Bragg mirror (9) located on both sides of the active layer (5). A phase change material layer (3) is disposed within the optical path of the optical resonant cavity; as well as An excitation unit, coupled to the phase change material layer (3), is used to apply energy stimulation to the phase change material layer (3); The phase change material layer (3) undergoes a controllable phase transition in response to the energy stimulus applied by the excitation unit. The phase transition causes a corresponding change in the refractive index of the phase change material layer (3) to adjust the equivalent cavity length of the optical resonant cavity.
2. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The phase change material layer (3) is integrated on one side of the first distributed Bragg reflector (1).
3. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, Also includes: The first conductive layer (4) is disposed between the active layer (5) and the first distributed reflector; The second conductive layer (6) is disposed between the active layer (5) and the second distributed reflector. The materials of the first conductive layer (4) and the second conductive layer (6) are N-type semiconductor material and P-type semiconductor material, respectively. A current limiting layer (7) is disposed on the side of the second conductive layer (6) away from the active layer (5); The first electrode (2) is disposed on the first conductive layer (4); The second electrode (8) is disposed on the side of the current limiting layer (7) away from the second conductive layer (6).
4. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The phase change material layer (3) is made of an amorphous, crystalline, or metastable structure between an amorphous and a crystalline state.
5. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The energy stimulus can be any one of thermal energy, electrical energy, light energy, or electro-thermal coupling.
6. The vertical-cavity surface-emitting laser according to claim 5, characterized in that, The excitation unit is a micro heater structure (12) disposed in the region adjacent to the phase change material layer (3), or an electrode structure (16) connected to the phase change material layer (3).