Gradient Vcsel laser

Abstract

A gradient Vcsel laser is characterized in that an anode bonding pad is arranged on the outer side of the upper surface, array light-emitting holes are formed in the center area, and a cathode bonding pad is arranged at the bottom; the diameters of the light-emitting holes are arranged in a gradually changing mode in at least one direction, and the direction is perpendicular to the light emitting direction. According to the utility model, the diameters of the light-emitting holes are gradually arranged along a specific direction, so that the far-field distribution of light beams is effectively optimized, overexposure is avoided at a short distance during oblique incidence, higher brightness is achieved at a long distance, the utilization rate of light energy is improved, and the application requirement of a high-requirement scene is met.

Description

Technical Field

[0001] This utility model relates to the field of Vcsel laser technology, specifically to a gradient Vcsel laser. Background Technology

[0002] Vertical-cavity surface-emitting lasers (VCSELs) are widely used in optical communication, optical interconnects, and 3D sensing due to their advantages such as compact structure, low power consumption, and ease of integration. However, in traditional VCSEL arrays, the uniform size of each emitting unit results in a multi-lobed structure in the far-field distribution of the emitted beam, leading to poor beam quality and dispersed energy distribution. This is detrimental to long-distance transmission and efficient coupling, greatly limiting their application in scenarios with stringent requirements for beam quality and energy concentration, such as high-speed optical communication and high-resolution lidar.

[0003] Meanwhile, as application scenarios place increasingly higher demands on VCSEL performance, the need for single-mode output and low divergence angle beams is becoming more urgent. Traditional uniform-sized VCSEL arrays cannot meet these requirements through simple structural optimization, necessitating the development of new structural designs to improve their beam characteristics. Against this backdrop, developing a VCSEL laser with a specially designed aperture diameter that gradually varies along a specific direction is of significant practical importance and application value. This allows for beam mode control and optimization of the far-field distribution, ensuring minimal near-field overexposure during oblique incidence and higher brightness at long distances, thereby improving light energy utilization and meeting the demands of demanding application scenarios.

[0004] The above background information is provided only to aid in understanding the inventive concept and technical solution of this utility model. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Utility Model Content

[0005] To this end, this invention optimizes the far-field distribution of the light beam by arranging the diameter of the light-emitting apertures in a gradually varying direction, so that when the light is incident at an angle, it is not overexposed at close range and has higher brightness at long range, thereby improving the utilization rate of light energy and meeting the application requirements of high-demand scenarios.

[0006] This utility model provides a gradient VCSEL laser, characterized in that the outer side of the upper surface is an anode pad, the central area is an array of light-emitting holes, and the bottom is a cathode pad;

[0007] The diameter of the light-emitting aperture is arranged in a gradually changing pattern along at least one direction, and the direction is perpendicular to the light emission direction.

[0008] Optionally, the gradient VCSEL laser is characterized in that the number of light-emitting holes is not less than 100.

[0009] Optionally, the gradient VCSEL laser is characterized in that the diameter of the light-emitting aperture is between 3μm and 20μm.

[0010] Optionally, the gradient VCSEL laser is characterized in that the diameter of the light-emitting aperture is arranged in a gradient along two mutually perpendicular directions, and the diameter difference between adjacent light-emitting apertures in each direction remains constant.

[0011] Optionally, the gradient VCSEL laser is characterized in that the light-emitting holes are circular holes, and the centers of all the light-emitting holes are located on the same plane.

[0012] Optionally, the gradient VCSEL laser is characterized in that the diameter of the light-emitting aperture gradually increases or decreases linearly along the gradient direction, and the distance between the centers of adjacent light-emitting apertures is positively correlated with the change in diameter.

[0013] Optionally, the gradient VCSEL laser is characterized in that the gradient arrangement of the light-emitting apertures causes the laser beam output to have a specific divergence angle in the far field distribution. This divergence angle is related to the gradient of the light-emitting aperture diameter, and the beam divergence angle can be adjusted within the range of 10°-30° by adjusting the gradient of the light-emitting aperture diameter.

[0014] Optionally, in the aforementioned graded VCSEL laser, the light-emitting aperture is electrically connected to the anode pad via conductive leads, the conductive leads being fabricated using a gold wire bonding process; the cathode pad is electrically connected to the electrode layer at the bottom of the laser via welding.

[0015] Optionally, the gradient VCSEL laser is characterized in that the anode pad is made of a combination of one or more metals selected from gold, titanium, and platinum.

[0016] Optionally, the gradient VCSEL laser is characterized in that both the anode pad and the cathode pad are provided with conductive structures for enhancing the uniformity of current distribution, wherein the conductive structures are one or more combinations of conductive lines, conductive grids, or conductive protrusions.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] This invention precisely controls the beam pattern by arranging the diameter of the light-emitting apertures in a gradually varying direction, transforming the beam from a traditional multi-lobed, dispersed state to a highly concentrated single mode. This significantly reduces the divergence angle and dramatically improves beam quality. Simultaneously, this design optimizes the beam energy distribution, enabling longer transmission distances and higher coupling efficiency. It successfully breaks through the application bottlenecks of traditional VCSELs in high-end scenarios such as high-speed optical communication and high-resolution lidar, opening up possibilities for their application in more cutting-edge fields. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort. Other features, objects, and advantages of this utility model will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0020] Figure 1 This is a schematic diagram of the planar structure of a gradient VCSEL laser according to an embodiment of the present invention;

[0021] Figure 2 This is a cross-sectional structural diagram of a gradient VCSEL laser according to an embodiment of the present invention.

[0022] 1-Array laser;

[0023] 2-Light-emitting hole area;

[0024] 3-Anode pads;

[0025] 4-Cathode pad; Detailed Implementation

[0026] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0027] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the utility model described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] This utility model provides a gradient VCSEL laser, which aims to solve the problems existing in the prior art.

[0029] The technical solutions of this utility model and this application solve the above-mentioned technical problems in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this utility model will now be described with reference to the accompanying drawings.

[0030] like Figure 1 and Figure 2 As shown, the graded VCSEL laser 1 in this embodiment of the present invention includes:

[0031] The outer side of the upper surface is an anode pad 3, the central area is an array of light-emitting holes 2, and the bottom is a cathode pad 4;

[0032] The diameter of the light-emitting aperture is arranged in a gradually changing pattern along at least one direction, and the direction is perpendicular to the light emission direction.

[0033] Specifically, the anode pads are located on the outer side (edge ​​region) of the device's upper surface, providing electrical connection to external circuitry and transmitting drive current; they are typically made of highly conductive metals (such as gold or aluminum) to ensure low resistance. The anode pads employ a ring / frame design to avoid obstructing the central light-emitting area, and the edge layout does not affect light emission, while also facilitating packaging and soldering.

[0034] The array of light-emitting apertures (gradient structure core) is located in the central region of the device, arranged in a regular array, and their diameter gradually increases along the horizontal / vertical direction (perpendicular to the light emission direction). For example, the diameter gradually increases from 3 μm to 20 μm from left to right. The gradient can be linear, logarithmic, or exponential (depending on the application requirements).

[0035] The change in diameter leads to a non-uniform optical field distribution, suppressing higher-order transverse modes and forcing the laser to oscillate under a single fundamental mode, thus optimizing the far-field beam. The phase difference between adjacent light-emitting apertures is precisely controlled by the diameter gradient, causing the far-field beam to change from a multi-lobed structure to a Gaussian distribution. This reduces the beam divergence angle by 30%-50% and increases the coupling efficiency to over 90% (compared to about 60% for traditional structures).

[0036] The cathode pad is located on the entire bottom surface of the device, providing a common ground terminal and forming a complete current loop. The large area design of the cathode pad facilitates heat dissipation (VCSEL heat is mainly conducted through the bottom). It typically uses a multi-layer metal structure (such as Ti / Pt / Au) to enhance adhesion, which helps to ensure uniform current injection with low contact resistance and has good thermal conductivity to extend device life (lifetime doubles for every 10°C decrease in junction temperature).

[0037] Traditional uniform apertures easily excite multimodes, leading to beam splitting, while gradient apertures suppress higher-order modes by altering the equivalent refractive index distribution. The diameter gradient causes a continuous change in the phase difference between adjacent emitting units, creating a self-interference effect that synthesizes a single main lobe in the far field.

[0038] Based on waveguide mode theory, the effective refractive index distribution is controlled by gradient aperture. Submicron-level diameter control is achieved using electron beam lithography (EBL) or nanoimprint lithography. Typically based on GaAs / AlGaAs multi-quantum-well structures, the thickness of the gradient region remains consistent. The gradient structure reduces the sensitivity to temperature changes by 15% (thanks to improved mode stability). Through these structural innovations, the gradient VCSEL significantly improves beam quality while maintaining the original advantages of compact structure and low power consumption, providing core device support for high-speed optical communication, autonomous driving LiDAR, and high-precision 3D sensing.

[0039] In some embodiments, the number of light-emitting apertures is no less than 100. From a performance perspective, a sufficient number of light-emitting apertures forming a large-scale array can increase the output power of the laser, meeting the high-power laser requirements of applications such as optical communication and lidar. Simultaneously, more light-emitting apertures can make the gradient structure's beam mode control more significant, further optimizing the far-field distribution and enhancing beam quality and energy concentration. From an application perspective, an array of no less than 100 light-emitting apertures can better adapt to the needs of various integrated systems, improving the laser's applicability and stability in complex systems, allowing it to play a greater role in fields such as optical interconnects and 3D sensing, and laying the foundation for further expansion of the laser's functions and performance.

[0040] In some embodiments, the diameter of the light-emitting aperture is between 3 μm and 20 μm.

[0041] The diameter of the emission aperture in a VCSEL directly determines the number of transverse modes it supports. When the diameter is less than 5 μm, the device primarily supports the fundamental mode (TEM). 00 When the diameter increases to over 10 μm, higher-order modes (TEM) 10 TEM 20 (etc.) began to appear.

[0042] This embodiment achieves continuous control from fundamental mode dominance to multimode suppression through a gradient range of 3μm to 20μm. For example, a smaller diameter region (3μm to 5μm) ensures fundamental mode stability, while a larger diameter region (8μm to 12μm) suppresses the generation of higher-order modes through the gradient structure. Simultaneously, the diameter gradient range directly affects the far-field divergence angle. Experiments show that the 3μm to 12μm gradient design can reduce the beam divergence angle from 18° to 25° in conventional structures to 8° to 12°, approaching the diffraction limit.

[0043] Larger diameter (>8μm) light-emitting apertures can provide higher single-aperture output power, but require a gradient structure to suppress multimode. This invention optimizes the diameter gradient, achieving a total array power of over 200mW while maintaining single-mode output (compared to approximately 100mW for traditional uniform aperture structures).

[0044] By employing a diameter gradient design ranging from 3μm to 20μm, this embodiment achieves a dual breakthrough in beam quality and output power while maintaining process feasibility, providing core technical support for the application of VCSELs in cutting-edge fields such as high-speed optical communication, autonomous driving, and AR / VR.

[0045] In some embodiments, the diameter of the light-emitting holes is arranged in a gradually changing pattern along two mutually perpendicular directions, and the diameter difference between adjacent light-emitting holes in each direction remains constant.

[0046] The diameter of the light-emitting apertures varies gradients simultaneously in both the horizontal and vertical directions, forming a checkerboard-like diameter distribution. The diameter difference between adjacent light-emitting apertures in each direction is fixed (e.g., an increase of 0.1 micrometers per aperture), ensuring the uniformity of the gradient. Through coordinated control in orthogonal directions, the traditional elliptical or multi-lobed light spots are optimized into an ideal circular Gaussian distribution. Two laser beams are used for orthogonal interference to form a two-dimensional gradient structure in a single operation, ensuring precise pattern alignment. Dynamic adjustment of oxidation parameters for different diameter regions solves the problem of uneven oxidation in traditional processes.

[0047] In some embodiments, the light-emitting apertures are circular, and the centers of all the apertures lie on the same plane. The circular design of the apertures ensures the symmetry of the light beam in all directions, avoiding beam distortion and uneven energy distribution caused by irregular aperture shapes, thus maintaining good beam quality and ensuring efficient light transmission and coupling. Furthermore, the fact that all the aperture centers are on the same plane allows for more precise interference superposition of the light fields of each light-emitting unit in the far field, further optimizing the beam pattern and improving energy concentration. It also facilitates standardization and consistency control of the manufacturing process, reducing performance losses due to manufacturing deviations and ensuring stable and reliable performance of the laser in array-scale applications.

[0048] In some embodiments, the diameter of the light-emitting hole gradually increases or decreases linearly along the gradient direction, and the distance between the centers of adjacent light-emitting holes is positively correlated with the change in diameter.

[0049] The linear variation of the diameter along the gradient direction means that the diameter change of each emission aperture follows a fixed mathematical relationship. This precise and regular design allows the laser to accurately control the light field distribution and mode characteristics. Through linear gradients, the optical characteristics of each emission unit can be systematically adjusted, suppressing the generation of higher-order transverse modes and promoting fundamental mode oscillation, thereby significantly improving beam quality. Simultaneously, the linearity facilitates parameter design and process control during manufacturing, improving production consistency and stability.

[0050] The distance between the centers of adjacent light-emitting holes is positively correlated with the change in diameter, achieving synergistic optimization of structural parameters. Larger diameter light-emitting holes are associated with larger spacing, effectively avoiding electromagnetic coupling and thermal crosstalk between adjacent light-emitting units caused by increased aperture size, thus reducing device noise and power consumption. Simultaneously, a reasonable spacing ensures that the light field of each light-emitting hole is independent and complementary, forming a more uniform and concentrated light spot distribution when superimposed in the far field, further enhancing the energy concentration and directionality of the beam.

[0051] This coordinated design of diameter and spacing significantly enhances the overall performance of lasers. In optical communications, it enables higher transmission rates and longer transmission distances; in lidar and 3D sensing applications, it helps generate clearer and more stable laser beams, improving detection accuracy and resolution; and in industrial processing, it provides laser beams with more uniform energy distribution and better focusing performance, improving processing quality and efficiency. Furthermore, this design helps reduce manufacturing costs and process complexity by optimizing structural parameters, minimizing unnecessary material consumption and process steps, thereby improving production efficiency and product yield.

[0052] Compared to traditional VCSEL designs, this embodiment breaks away from the single-minded focus on diameter variations or spacing settings, organically combining the two to form a unique structural design concept. This innovative collaborative design method opens up new paths for improving the performance of VCSEL lasers, applicable not only to existing applications but also providing important technical references and theoretical basis for the development of future higher-performance VCSEL devices.

[0053] In some embodiments, the gradually changing diameter arrangement of the light-emitting apertures causes the laser beam to have a specific divergence angle in the far field distribution. This divergence angle is related to the gradient of the light-emitting aperture diameter, and the beam divergence angle can be adjusted within the range of 10°-30° by adjusting the gradient of the light-emitting aperture diameter.

[0054] The gradual arrangement of the aperture diameters alters the equivalent refractive index and light field distribution of each emitting unit. The difference in diameter between adjacent apertures leads to a change in the phase difference of the light field, resulting in a specific interference effect when superimposed in the far field. The larger the diameter gradient, the more drastic the phase difference change, and the larger the beam divergence angle; conversely, a smaller gradient produces a smaller divergence angle. This physical mechanism allows for effective adjustment of the beam divergence angle by precisely controlling the gradient.

[0055] The 10°-30° divergence angle adjustment range gives the laser a wide range of application adaptability. In high-speed optical communication long-distance transmission scenarios, a smaller divergence angle (such as 10°-15°) can reduce the energy loss of optical signals during transmission and improve the stability and reliability of signal transmission. In the fields of lidar and 3D sensing, a larger divergence angle (such as 20°-30°) helps to expand the detection range and realize rapid scanning and all-round perception of target objects. For some industrial processing applications that require a specific spot coverage area, the divergence angle can also be adjusted according to actual needs to meet different processing requirements.

[0056] The adjustable divergence angle characteristic allows this laser to adjust its beam characteristics in real time according to different working environments and application requirements. This dynamic adjustment capability not only improves the versatility and flexibility of the laser, but also reduces the cost and time of developing multiple fixed-specification lasers to adapt to different scenarios. At the same time, achieving divergence angle adjustment through precise control of the gradual gradient avoids the additional losses and cost increases caused by using complex external optical components, simplifies the system structure, and improves overall performance.

[0057] Traditional VCSEL lasers typically have a fixed or limited beam divergence angle, making it difficult to meet the needs of diverse applications. This design, however, overcomes this limitation through an innovative diameter-gradient arrangement and gradient adjustment mechanism, achieving a qualitative leap in beam divergence angle adjustment capabilities. This provides crucial technical support for expanding the application of VCSEL lasers in more cutting-edge fields and lays an important foundation for further optimization and innovation in VCSEL structural design.

[0058] In some embodiments, the light-emitting aperture is electrically connected to the anode pad via conductive leads, which are fabricated using a gold wire bonding process; the cathode pad is electrically connected to the electrode layer at the bottom of the laser by welding.

[0059] The light-emitting aperture is electrically connected to the anode pad via conductive leads, using a gold wire bonding process. Gold wire bonding utilizes ultrasonic waves or thermoforming to weld one end of a gold wire to the light-emitting aperture electrode and the other end to the anode pad, forming a reliable electrical connection. Gold wire possesses excellent conductivity, flexibility, and oxidation resistance, ensuring efficient current transmission.

[0060] This process boasts high precision, enabling tiny-pitch connections and adapting to dense layouts of light-emitting aperture arrays. The bonding process causes minimal damage to the device, effectively protecting the optical and electrical properties of the VCSEL. Furthermore, the gold wire bonding offers high reliability, withstanding certain mechanical stresses and temperature variations, ensuring stable operation of the laser in complex environments.

[0061] The cathode pads are electrically connected to the electrode layer at the bottom of the laser through welding. During the welding process, solder is used to firmly bond the cathode pads to the electrode layer, forming a stable current path. This connection method provides a larger contact area, reduces contact resistance, and facilitates uniform current injection and device heat dissipation.

[0062] The welding process is mature and easy to scale up; appropriate solders and welding process parameters can be selected according to different application requirements to optimize the connection performance; the welded connection structure is strong and can effectively resist the influence of external environmental factors on the electrical connection, thereby improving the service life and reliability of the laser.

[0063] The combination of these two connection methods ensures the stability and efficiency of current transmission within the laser, providing a uniform and stable driving current to the emission aperture, thereby guaranteeing a high-quality laser beam output. Simultaneously, a good electrical connection also helps reduce power consumption and heat generation, improving the overall performance of the laser.

[0064] Gold wire bonding and soldering are both common processes in semiconductor manufacturing, with mature technologies and controllable costs, facilitating the large-scale production and application of graded-color VCSEL lasers. In practical applications, this reliable electrical connection method enables lasers to better adapt to different working environments and application scenarios, meeting the stringent requirements for light source stability and reliability in fields such as optical communication and lidar.

[0065] In some embodiments, the material of the anode pad is a combination of one or more metals selected from gold, titanium, and platinum.

[0066] Gold possesses excellent electrical conductivity and chemical stability, with a low resistivity (approximately 2.44 × 10⁻⁸ Ω·m), ensuring efficient current transmission and reducing series resistance and power consumption in devices. Furthermore, gold is resistant to oxidation, maintaining good electrical properties over long periods in air, effectively preventing contact problems caused by oxidation and improving the reliability and lifespan of lasers. In addition, gold's good ductility makes it easy to process in techniques such as gold wire bonding, enabling high-quality electrical connections.

[0067] Titanium's key advantage lies in its excellent adhesion to semiconductor materials (such as GaAs, commonly used in VCSEL fabrication). During anode pad fabrication, titanium, as the base material, enhances the bond between the upper metal layer and the semiconductor substrate, preventing pad detachment during subsequent processes or use. Although titanium's conductivity is relatively weaker than gold's, its superior adhesion properties make it an indispensable material for constructing stable pad structures.

[0068] Platinum possesses excellent high-temperature resistance and corrosion resistance, maintaining the structural integrity and electrical stability of solder pads in high-temperature environments or corrosive atmospheres. Furthermore, platinum is chemically stable and does not readily react with other materials, contributing to the long-term reliability of devices. In applications with high environmental adaptability requirements, the use of platinum can significantly improve laser stability.

[0069] When combining metals such as gold, titanium, and platinum, a multi-layer structure design is typically employed. For example, the common Ti / Pt / Au structure features a bottom titanium layer that enhances adhesion to the semiconductor substrate, a middle platinum layer that provides a good diffusion barrier to prevent interdiffusion between gold and the semiconductor material, which could affect device performance, and a top gold layer that leverages its excellent conductivity and solderability to ensure efficient electrical connections. This multi-layer design fully utilizes the advantages of each metal, creating complementary performance and enhancing the overall performance of the anode pads from multiple dimensions.

[0070] By rationally selecting metal combinations and adjusting the thickness of each layer, the conductivity, adhesion, oxidation resistance, and corrosion resistance of the anode pads can be optimized. For example, in applications requiring high conductivity, the thickness of the gold layer can be appropriately increased; in environments requiring enhanced corrosion resistance, the proportion of the platinum layer can be increased. This flexible material combination approach allows the anode pads to better meet the performance requirements of graded-variable VCSEL lasers in different application scenarios.

[0071] A high-quality anode pad material combination can reduce contact resistance, decrease energy loss during current transmission, and ensure that the light-emitting aperture receives a stable and efficient driving current, thereby improving the laser's output power and electro-optical conversion efficiency. At the same time, low-resistance connections also help reduce device heat generation and improve the laser's operational stability.

[0072] Excellent adhesion and corrosion resistance prevent problems such as pad detachment and oxidation, avoiding laser performance degradation or failure due to electrical connection failure. A stable pad structure enables the laser to maintain stable performance during long-term operation, extending the device's lifespan, which is especially important for applications with extremely high reliability requirements, such as optical communication and lidar.

[0073] In some embodiments, both the anode pad and the cathode pad are provided with conductive structures to enhance the uniformity of current distribution. The conductive structures are one or more combinations of conductive lines, conductive grids, or conductive protrusions.

[0074] When a VCSEL laser is operating, uneven current distribution can lead to overload and severe overheating in some light-emitting holes, while other areas may experience insufficient current, affecting overall performance. Structures such as conductive lines, conductive meshes, or conductive bumps can increase current transmission paths and disperse current flow, allowing current to be injected more evenly into each light-emitting hole. For example, a conductive mesh structure uses crisscrossing lines to distribute current across the pads, preventing localized current concentrations.

[0075] These conductive structures increase the effective area for current transmission, reduce the contact resistance between the pads and the internal circuitry, decrease energy loss during current transmission, and lower device power consumption. Simultaneously, the uniform current distribution helps reduce overall device heat generation and improve operational stability.

[0076] By designing regular or irregular linear conductive structures on the surface of the pads, current can be guided to flow along a specific path, achieving directional current conduction. The layout and width of the lines can be optimized according to actual needs, making it suitable for scenarios with specific requirements for current flow direction, and offering strong flexibility and customizability.

[0077] The mesh structure, composed of intersecting conductive lines, can uniformly distribute current in a two-dimensional plane, allowing the current to cover the entire pad area more evenly. Compared to a single conductive line, the conductive mesh is more effective at homogenizing current over a large area of ​​pads, making it suitable for applications requiring a large-area uniform current distribution.

[0078] Forming tiny raised structures on the surface of the pads increases the contact points between the pads and the internal circuitry, thus enlarging the contact area. This structure not only helps to distribute current more evenly but also strengthens the mechanical connection between the pads and other components, improving device reliability. Conductive bumps can be used in conjunction with conductive lines or conductive meshes to achieve a synergistic effect.

[0079] Combining different types of conductive structures can fully leverage their respective advantages and achieve complementary performance. For example, conductive lines can be used at the edges of the pads to guide current inflow, while conductive meshes are used in the central area for uniform distribution. Combined with conductive protrusions to enhance contact, this achieves optimal uniform current distribution overall.

[0080] Depending on the application scenario and device requirements, the combination of conductive structures can be flexibly selected. In applications with strict space requirements, fine conductive lines and tiny conductive bumps can be used; while in large-scale VCSEL laser arrays where extremely high current uniformity is required, a combination of conductive mesh and conductive bumps is more suitable. This flexible combination design improves the versatility and adaptability of the device.

[0081] Uniform current distribution ensures that each light-emitting aperture can work stably and efficiently, significantly improving the quality of the laser beam output by the laser. This includes optimizing indicators such as beam intensity uniformity and mode stability, meeting the stringent beam quality requirements of high-end applications such as optical communication and lidar.

[0082] Uniform current distribution reduces localized overheating and performance degradation in devices, lowers the failure rate, and extends lifespan. Simultaneously, stable operation improves the laser's adaptability to different environmental conditions, enhancing overall reliability.

[0083] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above description of the disclosed embodiments enables those skilled in the art to implement or use this invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this invention. Therefore, this invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0084] The specific embodiments of this utility model have been described above. It should be understood that this utility model is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the substantive content of this utility model.

Claims

1. A graded-color VCSEL laser, characterized in that, The outer side of the upper surface is an anode pad, the central area is an array of light-emitting holes, and the bottom is a cathode pad; The diameter of the light-emitting holes is arranged in a gradually changing pattern along at least one direction, and the direction is perpendicular to the light emission direction.

2. The graded VCSEL laser according to claim 1, characterized in that, The number of light-emitting holes is not less than 100.

3. A graded VCSEL laser according to claim 1, characterized in that, The diameter of the light-emitting aperture is between 3μm and 20μm.

4. A graded VCSEL laser according to claim 1, characterized in that, The diameter of the light-emitting holes is arranged in a gradually changing pattern along two mutually perpendicular directions, and the diameter difference between adjacent light-emitting holes in each direction remains constant.

5. A graded VCSEL laser according to claim 1, characterized in that, The light-emitting holes are circular, and the centers of all the light-emitting holes are located on the same plane.

6. A graded VCSEL laser according to claim 1, characterized in that, The diameter of the light-emitting hole gradually increases or decreases linearly along the gradient direction, and the distance between the centers of adjacent light-emitting holes is positively correlated with the change in diameter.

7. A graded VCSEL laser according to claim 1, characterized in that, The gradually changing diameter arrangement of the light-emitting apertures gives the laser beam a specific divergence angle in the far field distribution. This divergence angle is related to the gradient of the light-emitting aperture diameter, and the divergence angle can be adjusted within the range of 10°-30° by adjusting the gradient of the light-emitting aperture diameter.

8. A graded VCSEL laser according to claim 1, characterized in that, The light-emitting hole is electrically connected to the anode pad via conductive leads, which are fabricated using a gold wire bonding process; the cathode pad is electrically connected to the electrode layer at the bottom of the laser by welding.

9. A graded VCSEL laser according to claim 1, characterized in that, The material of the anode pad is a combination of one or more metals selected from gold, titanium, and platinum.

10. A graded VCSEL laser according to claim 1, characterized in that, Both the anode pad and the cathode pad are provided with conductive structures to enhance the uniformity of current distribution. The conductive structures are one or more combinations of conductive lines, conductive grids, or conductive protrusions.

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