A graded VCSEL laser

Abstract

A gradient VCSEL laser is characterized by a central region comprising an array of light-emitting holes and a bottom region comprising a cathode pad. The light-emitting holes are divided into several sections, each with an independent anode pad. The brightness of different sections can be controlled by an external driving current, achieving a gradual change in brightness in the vertical direction. In this invention, each light-emitting hole section is equipped with an independent anode pad, allowing for precise control of the brightness of each section via an external driving current. This enables active brightness gradation in the vertical direction, providing rapid response to scene changes and meeting the needs of high-speed dynamic applications.

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), as a new generation of optoelectronic devices, offer advantages such as low power consumption, high-speed modulation, and circular beams, and have been widely used in fields such as 3D sensing, data communication, and LiDAR. Traditional VCSELs typically employ a monolithic driving structure, where all emitting units share the same anode, resulting in a uniformly distributed light field. However, with the increasing complexity of application scenarios, a uniform light field can no longer meet the needs of specific fields.

[0003] In applications requiring gradual brightness changes (such as structured light projection, edge illumination, beam shaping, etc.), traditional VCSELs have the following problems:

[0004] Insufficient light field modulation capability: The overall driving structure cannot achieve independent brightness control in different areas, and secondary modulation is required through external optical elements (such as filters and diffractive optical elements), which leads to increased system complexity and aggravated light energy loss.

[0005] Limited dynamic response: The passive modulation method of external optical components is difficult to achieve high-speed dynamic changes, which cannot meet the needs of rapid scene switching (such as dynamic 3D modeling and adaptive lighting).

[0006] Low energy efficiency: To achieve gradual brightness changes, it is usually necessary to reduce light intensity after global driving, resulting in a large amount of energy waste, which is not in line with the trend of energy conservation and environmental protection.

[0007] Integration bottleneck: Traditional solutions require additional optical components, which increases the system size and makes it difficult to meet the miniaturization and lightweight application requirements (such as consumer electronics and automotive devices).

[0008] 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

[0009] Therefore, each light-emitting hole section in this invention is equipped with an independent anode pad, which can precisely control the brightness of each area through external driving current, realize active brightness gradient in the vertical direction, and quickly respond to scene changes to meet the needs of high-speed dynamic applications.

[0010] This utility model provides a gradient VCSEL laser, characterized in that the central region is an array of light-emitting holes and the bottom is a cathode pad;

[0011] The light-emitting aperture has several partitions, each partition having an independent anode pad, which can control the brightness of different areas through an external driving current to achieve a gradual change in brightness in the vertical direction.

[0012] Optionally, the gradient VCSEL laser is characterized in that the array of light-emitting holes in the central region is distributed in a regular rectangular array, circular array, or hexagonal array.

[0013] Optionally, the gradient VCSEL laser is characterized in that each partition of the light-emitting aperture is circular, square, or polygonal in shape, and the shapes of different partitions may be the same or different.

[0014] Optionally, the gradient VCSEL laser is characterized in that the number of partitions is 2-10, and the area of ​​each partition is the same or different.

[0015] Optionally, the gradient VCSEL laser is characterized in that an insulating layer is provided between the cathode pad and the anode pad, and the insulating layer is made of silicon oxide or silicon nitride.

[0016] Optionally, in a gradient VCSEL laser, the driving current is connected to each of the individual anode pads via wires, the wires being made of the same or compatible conductive material as the anode pads.

[0017] Optionally, the gradient VCSEL laser is characterized in that the brightness gradient in the vertical direction is achieved by controlling the magnitude of the driving current in different zones, and the magnitude of the driving current is positively correlated with the brightness of the corresponding zone.

[0018] Optionally, the gradient VCSEL laser is characterized in that the edge of the partition is provided with a reflective structure to improve the light reflection efficiency and enhance the light emission effect.

[0019] Optionally, the gradient VCSEL laser is characterized in that an annular heat-conducting groove for heat dissipation is provided around the array light-emitting holes, the annular heat-conducting groove is integrally formed with the laser substrate, and the interior is filled with thermally conductive adhesive with a high thermal conductivity.

[0020] Optionally, the graded VCSEL laser is characterized in that a refractive index graded layer is provided at the boundary of the partition to smooth the difference in the output angle between adjacent partitions.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] Each light-emitting hole section of this invention is equipped with an independent anode pad, which can independently control the brightness of different areas through external driving current, achieving precise brightness gradient in the vertical direction without relying on external optical components.

[0023] The number of light-emitting holes in each partition of this invention can be configured according to a preset brightness gradient curve, supporting linear, non-linear or segmented gradients to meet the needs of different application scenarios (such as 3D sensing and beam shaping). Attached Figure Description

[0024] 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:

[0025] Figure 1 This is a schematic diagram of the planar structure of a gradient VCSEL laser according to an embodiment of the present invention;

[0026] Figure 2 This is a cross-sectional structural diagram of a gradient VCSEL laser according to an embodiment of the present invention.

[0027] 1-Array laser;

[0028] 2-Light-emitting hole area;

[0029] 3-Anode pads;

[0030] 4-Cathode pad; Detailed Implementation

[0031] 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.

[0032] 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.

[0033] This utility model provides a gradient VCSEL laser, which aims to solve the problems existing in the prior art.

[0034] 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.

[0035] like Figure 1 and Figure 2 As shown, the graded VCSEL laser 1 in this embodiment of the present invention includes:

[0036] The central area is an array of light-emitting holes 2, and the bottom is a cathode pad 4;

[0037] The light-emitting hole has several partitions, each partition having an independent anode pad 3, which can control the brightness of different areas through external driving current to achieve a gradual change in brightness in the vertical direction.

[0038] Specifically, the central region array of light-emitting holes is located in the central region of the graded-ratio VCSEL laser and is the core component that enables the laser to emit light. It consists of multiple light-emitting holes arranged in a specific array. Based on the principle of vertical cavity surface emitting laser (VCSEL), by constructing a suitable resonant cavity structure in a semiconductor material, when electron-hole pairs recombine in the active region, photons are released. These photons are continuously reflected and amplified within the resonant cavity and are finally emitted vertically from the surface of the light-emitting holes.

[0039] The light-emitting aperture is divided into several zones, a design intended to achieve a gradual change in brightness along the vertical direction. Different zones can be controlled independently, allowing adjustment of their brightness according to specific needs. The number and shape of the zones can be optimized based on the specific application scenario and design requirements; for example, the number of zones may be 2-10 or more, and the shape can be circular, square, or polygonal. As a laser emission source, it generates a laser beam with a specific wavelength and direction. By controlling the brightness of different zones, the brightness distribution of the laser in the vertical direction can be adjusted to meet the requirements of different applications for laser beam characteristics, such as the specific needs for light intensity distribution in laser projection, lighting, and communication.

[0040] The bottom cathode pad, located at the bottom of the graded-color VCSEL laser, is a conductive area that connects to the internal circuitry of the laser. It is typically made of a highly conductive metal, such as gold, silver, copper, or their alloys. Serving as the laser's cathode connection point, it electrically connects the laser to the cathode of external circuitry. Through the bottom cathode pad, an external power supply can provide the current required for the laser's operation, enabling the electron-hole recombination process within the laser to occur, thereby generating laser light.

[0041] To some extent, the bottom cathode pad also has a heat dissipation function. Since the laser generates heat during operation, the bottom cathode pad is in contact with external heat dissipation structures (such as heat dissipation layers on circuit boards), which can conduct some of the heat away, helping to maintain the laser's stable operating temperature and ensuring its performance and lifespan.

[0042] Each light-emitting aperture section has an independent anode pad, located on the upper surface of the laser or other suitable position, connected to the anode of the corresponding aperture section. These pads are also made of a highly conductive metal, such as gold, silver, copper, or their alloys. The independent anode pads are key components for controlling the brightness of different sections. Through an external driving circuit, different driving currents are applied to each independent anode pad, thereby controlling the brightness of the corresponding aperture section. The magnitude of the driving current is positively correlated with the brightness of the corresponding section; that is, the larger the driving current, the higher the brightness of the aperture section; conversely, the smaller the driving current, the lower the brightness.

[0043] Independent anode pads are connected to external drive circuits via wires to transmit electrical signals. Simultaneously, appropriate isolation measures are required between the independent anode pads of each zone, such as installing insulating layers or using isolation structures formed by photolithography or etching processes, to prevent current interference between different zones and ensure that each zone can independently and precisely control its brightness.

[0044] External drive current is generated by an external drive circuit, which typically consists of a power supply, a driver chip, resistors, capacitors, and other components. The power supply provides basic electrical energy, the driver chip adjusts the magnitude and waveform of the current according to the control signal, and the resistors and capacitors are used to stabilize the current and filter it.

[0045] An external drive current is connected to each individual anode pad via wires to control the brightness of the light-emitting holes in different zones. Various control methods can be used, such as pulse width modulation (PWM), which adjusts the pulse width to change the average value of the drive current, thus achieving fine-tuning of brightness gradients. Alternatively, analog control can be used to directly adjust the magnitude of the drive current to control the brightness.

[0046] In some embodiments, each partition of the light-emitting hole is circular, square, or polygonal in shape, and the shapes of different partitions may be the same or different.

[0047] Circular partitioning offers numerous advantages. From an optical perspective, the geometric symmetry of a circle facilitates more uniform laser propagation and reflection within the emission aperture. In a laser resonant cavity, the relatively simple and regular boundary conditions of a circle reduce light scattering and reflection losses at the boundaries, thereby improving laser emission efficiency and beam quality. Furthermore, circular partitioning is relatively easy to manufacture. Common micro-nano fabrication techniques such as photolithography and etching allow for precise control of the size and shape of the circular emission aperture, ensuring uniformity and consistency within the partition.

[0048] Square partitions: Square partitions facilitate layout design and calculation. In laser arrays, square partitions can be closely arranged to form a regular grid structure, which is beneficial for improving array integration and space utilization. Simultaneously, when integrated with other optical components or circuits, square partitions can better match square or rectangular interfaces, reducing optical or electrical performance losses caused by shape mismatches. From a mechanical perspective, square partitions exhibit relatively uniform stress distribution under thermal or mechanical stress, contributing to improved laser stability and reliability.

[0049] Polygonal partitioning: Polygonal partitioning (such as triangles, hexagons, etc.) offers greater design flexibility. When hexagonal partitions are closely arranged, the gaps between adjacent partitions are minimized, maximizing the array's fill factor and thus increasing the overall luminous power of the laser. Triangular partitioning can be used for specialized optical designs; for example, in applications requiring specific light intensity distribution or beam deflection, triangular partitions can achieve specific optical effects by adjusting their angles and dimensions.

[0050] Identical partition shapes: When different partitions have the same shape, the manufacturing process can be more standardized and simplified. During production, the same set of molds or processing parameters can be used to manufacture all partitions, reducing production costs and process complexity. At the same time, partitions with identical shapes exhibit better consistency in optical and electrical performance, facilitating unified design and optimization of the laser. For example, in lasers requiring uniform brightness gradients, partitions with identical shapes can achieve smooth brightness transitions through precise control of the drive current.

[0051] Different partition shapes: Partitions of different shapes can be customized to meet specific application requirements. In applications with special requirements for light intensity distribution, such as laser projection displays that need to achieve specific images or patterns, partitions of different shapes can change the light intensity distribution by adjusting their area, angle, and position, thereby achieving more complex optical effects. Furthermore, partitions of different shapes can also be used to optimize the heat dissipation performance of the laser; for example, using partitions with better heat dissipation performance in certain high-heat areas can improve the stability and lifespan of the laser.

[0052] In some embodiments, the number of partitions is 2-10, and the area of ​​each partition may be the same or different.

[0053] When all partitions have the same area, the laser design is more uniform, resulting in better consistency in optical and electrical performance. During manufacturing, all partitions can be produced using the same set of process parameters and molds, simplifying the manufacturing process and improving production efficiency and product yield. For example, in applications requiring uniform brightness output, such as planar lighting, partitions of the same area can achieve uniform brightness distribution through the same drive current, ensuring uniform lighting effects.

[0054] Using partitions of the same area simplifies control calculations. The external drive circuit can allocate drive current according to a uniform rule based on the number and area of ​​the partitions, achieving precise control of brightness gradients. Furthermore, partitions of the same area simplify the model and calculation process during optical simulation and design, improving design efficiency.

[0055] The varying sizes of each zone allow for targeted brightness adjustments based on specific application needs. In applications with specific requirements for localized light intensity, such as laser engraving where different engraving depths are needed in different areas, this can be achieved by adjusting the area and driving current of each zone. Larger zones can withstand greater driving current, producing higher brightness and thus achieving a stronger engraving effect; while smaller zones can achieve a weaker engraving effect with less driving current, meeting the needs of fine engraving.

[0056] Different area partitions can also be used to optimize the heat dissipation performance of lasers. In some high-heat areas, the area of ​​the partitions can be appropriately increased to increase the heat dissipation area and improve heat dissipation efficiency, thereby reducing the operating temperature of the laser and ensuring its performance and lifespan. At the same time, by rationally designing the layout of partitions with different areas, the internal heat distribution of the laser can be improved, reducing the risk of performance degradation and damage caused by local overheating.

[0057] In some embodiments, an insulating layer is provided between the cathode pad and the anode pad, and the insulating layer is made of silicon oxide or silicon nitride.

[0058] An insulating layer prevents short circuits: In graded-frequency VCSEL lasers, the cathode and anode pads serve as different electrodes, handling current input and output. Without an insulating layer, current could flow directly between the cathode and anode pads during operation, causing a short circuit. A short circuit not only prevents the laser from functioning properly but can also damage internal components due to excessive current, severely impacting the laser's performance and lifespan.

[0059] The insulating layer ensures stable electrical performance: It effectively reduces electrical interference between the cathode and anode pads. During laser operation, various electromagnetic signals may exist in the surrounding environment, potentially affecting current transmission between the cathode and anode pads. The insulating layer blocks external electromagnetic interference, ensuring that current flows accurately to each zone's emission aperture according to the designed path, thereby guaranteeing the stability and reliability of the laser's electrical performance.

[0060] Silicon oxide is a material with high resistivity, effectively preventing current leakage between the cathode and anode pads. Its insulation properties are stable, maintaining reliable insulation throughout the normal operating temperature range of the laser (typically -40°C to 125°C or higher, depending on the laser design), ensuring the laser's electrical safety. Silicon oxide possesses excellent chemical stability, resisting corrosion from chemicals that may be present inside the laser. During laser manufacturing and use, certain chemical reagents or specific chemical environments may be used; the silicon oxide insulating layer does not react with these chemicals, thus ensuring the integrity of the insulating layer and the long-term stability of its insulation performance. Silicon oxide is a commonly used material in semiconductor manufacturing processes, with mature preparation processes such as chemical vapor deposition (CVD) and thermal oxidation, which allow for precise control of silicon oxide thickness and uniformity. This makes the silicon oxide insulating layer highly compatible with the manufacturing processes of other laser components (such as cathode pads, anode pads, and apertures), reducing manufacturing difficulty and cost.

[0061] Silicon nitride has a high dielectric constant, meaning that, for the same thickness, a silicon nitride insulating layer can withstand higher voltages without breakdown. In lasers, where a larger driving voltage is required to achieve a specific luminescence effect, the silicon nitride insulating layer provides more reliable insulation, ensuring the safe operation of the laser under high-voltage conditions. Silicon nitride also possesses high mechanical strength and hardness, enabling it to withstand certain mechanical and thermal stresses. During laser operation, stress and deformation may occur between the cathode and anode pads due to current flow and heat generation. The silicon nitride insulating layer resists these stresses and deformations, maintaining its structural integrity and preventing short circuits caused by insulation layer rupture. In some special application environments, such as aerospace and nuclear industries, lasers may be affected by radiation. Silicon nitride has excellent radiation resistance, maintaining stable insulation and physical properties under radiation environments, ensuring reliable laser operation in these harsh environments.

[0062] By effectively isolating the cathode and anode pads, current leakage and electrical interference are reduced. The insulating layer ensures that more current is used to drive the light-emitting aperture, thereby improving the laser's luminous efficiency. This means that with the same input power, the laser can produce a stronger laser output, or require less input power to achieve the same laser output, thus reducing energy consumption.

[0063] Stable insulation properties help reduce performance fluctuations of lasers during operation. Because the insulation layer can block external interference and internal current leakage, the laser's performance parameters such as brightness and wavelength can be maintained more stably within the design range, improving the reliability and consistency of the laser during long-term operation and meeting the performance stability requirements of various application scenarios.

[0064] In some embodiments, the drive current is connected to each individual anode pad via a wire made of the same or compatible conductive material as the anode pad.

[0065] The driving current is connected to each individual anode pad via wires, which act as a crucial bridge for current transmission. They accurately deliver the current generated by the external driving circuit to each anode pad, providing the necessary power for the corresponding LED apertures to emit laser light. If the wires are poorly connected or have open circuits, the current will not be able to reach the anode pads properly, causing the corresponding LED apertures to fail to emit light, severely impacting the overall performance of the laser.

[0066] Because each light-emitting aperture section has an independent anode pad, the connection between the wires and the anode pads allows the external drive circuit to independently control the current of each section. By adjusting the current transmitted on different wires, the brightness of the corresponding light-emitting aperture section can be precisely controlled, thus achieving a vertical brightness gradient effect. This zone control capability is key to enabling diverse applications of graded VCSEL lasers.

[0067] When using the same conductive material, it has the following advantages:

[0068] Electrical Performance Matching: When the conductor uses the same conductive material as the anode pad, the electrical performance of the two can be perfectly matched. Identical materials have similar electrical parameters such as resistivity and conductivity, which helps reduce current loss and interference during transmission. For example, if both the anode pad and the conductor are made of gold, the identical material properties will prevent additional resistance or capacitance effects due to material differences during current transmission, ensuring efficient and stable current transmission to the anode pad.

[0069] High process compatibility: Using the same conductive material improves the compatibility of manufacturing processes. In laser manufacturing, the fabrication of anode pads and wires typically requires the same process steps, such as photolithography, etching, and metal deposition. Using the same material allows these processes to proceed more smoothly, reducing the need for additional process adjustments and optimizations due to material differences, lowering manufacturing difficulty and costs, and improving production efficiency and product consistency.

[0070] When compatible with conductive materials, it has the following advantages:

[0071] Functional Complementarity and Optimization: In some cases, although the conductors and anode pads use different conductive materials, these materials exhibit good compatibility. Compatible conductive materials can achieve complementary and optimized performance. For example, the anode pads might use a material with good adhesion and corrosion resistance, while the conductors use a material with higher conductivity. In this way, the anode pads can ensure a robust connection and long-term stability to the internal structure of the laser, while the conductors can provide more efficient current transmission, thereby improving the overall performance of the laser.

[0072] Cost and performance balance: Using compatible conductive materials can also achieve a balance between cost and performance. Some high-performance conductive materials are expensive, and using them exclusively for anode pads and wires could lead to excessively high laser costs. By selecting conductive materials that are compatible with anode pads but have lower costs for wires, the manufacturing cost of the laser can be reduced while maintaining certain performance, thus improving the product's market competitiveness.

[0073] In some embodiments, the vertical brightness gradient is achieved by controlling the magnitude of the driving current for different zones, and the magnitude of the driving current is positively correlated with the brightness of the corresponding zone.

[0074] The emission of a graded-gradient VCSEL laser is based on the principle of stimulated emission of semiconductor materials. When a driving current is applied between the anode and cathode pads, electrons and holes in the semiconductor material recombine in the active region, releasing photons and thus generating laser light. Different zones correspond to different emission areas in the vertical direction of the laser, and each zone can independently receive the driving current.

[0075] The magnitude of the driving current directly affects the recombination rate of electron-hole pairs in the active region of each zone. When the driving current increases, the number of charge carriers (electrons and holes) injected into the active region increases, the recombination probability of electron-hole pairs increases, and the number of photons released per unit time increases, leading to enhanced luminous intensity in that zone, i.e., increased brightness. Conversely, when the driving current decreases, the number of charge carriers decreases, the recombination rate decreases, the luminous intensity weakens, and the brightness decreases. By precisely controlling the magnitude of the driving current in different zones, differences in brightness between zones in the vertical direction can be achieved, thus creating a gradual brightness effect.

[0076] In certain simple applications or under ideal operating conditions, there may be a linear positive correlation between the magnitude of the driving current and the brightness of the corresponding partition. For example, within a small range of driving current, as the driving current increases uniformly, the recombination rate of charge carriers in each partition increases almost proportionally, resulting in an almost proportional increase in luminous intensity and brightness. This linear relationship facilitates precise control and calculation of the laser's brightness. In applications requiring high precision in brightness gradients, such as high-precision laser projection displays, the desired brightness gradient effect can be achieved by simply adjusting the magnitude of the driving current.

[0077] However, in practical applications, the relationship between drive current and zone brightness is often not strictly linear. When the drive current increases to a certain extent, the increase in brightness may gradually decrease due to factors such as changes in carrier scattering and recombination mechanisms within the semiconductor material, as well as thermal effects, exhibiting a nonlinear positive correlation. For example, at high current densities, the temperature within the active region increases significantly, leading to intensified thermal excitation and scattering of carriers. Some energy is dissipated as heat rather than converted into light energy, thus slowing down the rate of brightness increase. Nevertheless, an increase in drive current will still generally lead to an increase in zone brightness, but the magnitude and pattern of this increase become more complex.

[0078] The method of controlling the magnitude of the driving current in different zones to achieve gradual brightness changes brings extremely high application flexibility to lasers.

[0079] In some embodiments, the edge of the partition is provided with a reflective structure to improve the light reflection efficiency and enhance the light emission effect.

[0080] In a graded-gradient VCSEL laser, each zone is a vertically independent light-emitting region where light is generated and propagates outward. The zone edges serve as boundaries for light propagation; without proper treatment, some light may leak out directly from these edges, resulting in energy loss. Adding reflective structures creates reflective interfaces at the zone edges, restricting the light propagation path and confining more light within the zone or allowing it to propagate in the intended direction, thus reducing unnecessary light leakage.

[0081] Each zone needs to independently achieve brightness adjustment and emission functions, and the reflective structure at the zone edge can prevent light interference between adjacent zones. When light is reflected back at the zone edge, it can prevent light from entering adjacent zones, ensuring the independence and accuracy of the emission effect of each zone. This is crucial for achieving precise brightness gradation in the vertical direction.

[0082] Reflective structures can utilize the principle of total internal reflection to improve light reflection efficiency. When light travels from the interior of a partition with a higher refractive index to the surface of a reflective structure with a lower refractive index, total internal reflection occurs if the angle of incidence is greater than the critical angle, causing the light to be almost completely reflected back into the partition. This total internal reflection method minimizes light transmission loss, retaining more light energy within the partition, thereby improving light reflection efficiency.

[0083] Reflective structures can also employ multi-layer reflective film designs. Multi-layer reflective films are composed of alternating layers of materials with different refractive indices, each layer exhibiting a certain degree of reflection and transmission of incident light. By precisely designing the thickness and refractive index of each layer, the reflective film can strongly reflect light of specific wavelengths while further attenuating transmitted light. This multi-layer reflective film structure significantly improves light reflection efficiency, allowing more light to be reflected back to the luminous area, thus enhancing the luminous effect.

[0084] Because the reflective structure improves light reflection efficiency and reduces light leakage and loss, more light can be emitted from the partition surface, thereby directly increasing the brightness of the partition. In a graded-gradient VCSEL laser, the increase in brightness of each partition helps to achieve a more obvious vertical brightness gradient effect, enabling the laser to exhibit clearer and stronger brightness contrasts under different operating conditions.

[0085] Reflective structures can also optimize the distribution of light intensity. By rationally designing the shape and angle of the reflective structure, the reflected light can be redistributed within the zone, resulting in a more uniform distribution of light intensity across the emitting area. This is crucial for applications requiring high uniformity of light intensity, such as laser lighting and laser projection displays. A uniform light intensity distribution improves the quality of lighting or projection, reduces bright spots and dark areas, and makes the image or lighting effect clearer and more natural.

[0086] Besides increasing brightness and optimizing light intensity distribution, reflective structures can also improve the overall luminous efficiency of lasers. Luminous efficiency refers to the efficiency with which a laser converts electrical energy into light energy. Reflective structures reduce light energy loss, allowing more electrical energy to be converted into light energy, thereby improving the luminous efficiency of the laser. This not only helps reduce the energy consumption of the laser but also extends its lifespan and reduces the risk of performance degradation and damage due to heat generation.

[0087] In some embodiments, an annular heat-conducting groove for heat dissipation is provided around the array light-emitting holes. The annular heat-conducting groove is integrally formed with the laser substrate and is filled with thermally conductive adhesive with a high thermal conductivity.

[0088] The array of light-emitting apertures in a graded-gradient VCSEL laser is the main heat-generating region. During operation, current passes through the active region within the apertures, causing electrons and holes to recombine and emit light. However, this process is not 100% efficient; most of the electrical energy is released as heat. Because the apertures are densely arranged in an array, heat is highly concentrated in this region. If it cannot be dissipated in time, it can lead to a rapid increase in local temperature.

[0089] High temperatures have multiple adverse effects on laser performance. Firstly, increased temperature alters the band structure of semiconductor materials, causing wavelength shift and affecting output characteristics. Secondly, high temperatures increase carrier scattering probability and decrease carrier mobility, thus reducing electron-hole recombination efficiency, leading to decreased luminous intensity and efficiency. Furthermore, prolonged exposure to high temperatures accelerates the aging and damage of internal laser materials, shortening the laser's lifespan. Therefore, designing a heat dissipation structure around the array's light-emitting apertures is crucial; the annular heat-conducting groove is an effective heat dissipation solution designed to address this issue.

[0090] The annular heat-conducting groove and the laser substrate are integrally molded, meaning they are formed simultaneously using the same manufacturing process and possess the same material properties and structural integrity. This integrated structure avoids stress concentration and connection failure issues caused by the connection between different components, improving the structural stability between the heat-conducting groove and the substrate. During laser operation, even under the influence of external factors such as thermal expansion and contraction, the heat-conducting groove remains tightly bonded to the substrate, ensuring unobstructed heat dissipation.

[0091] The one-piece molding design simplifies the laser manufacturing process. Compared to manufacturing the substrate and heat sink separately and then assembling them, one-piece molding reduces assembly steps and potential sources of error, lowering manufacturing costs and time. Simultaneously, one-piece molding allows for better control over the size and shape accuracy of the heat sink, ensuring its compatibility with the array of light-emitting holes and improving heat dissipation.

[0092] The one-piece molded structure eliminates the need for an additional thermal resistance layer between the heat-conducting groove and the substrate, allowing heat to be conducted more directly and quickly from the light-emitting aperture area to the substrate, and then dissipated into the surrounding environment through the substrate. This efficient heat conduction path helps reduce the temperature in the light-emitting aperture area and improves the heat dissipation performance of the laser.

[0093] Although the annular heat-conducting groove is integrally molded with the laser substrate, some tiny gaps or uneven surfaces may still exist during the actual manufacturing process. A thermally conductive adhesive with a high thermal conductivity can fill these gaps, creating a tighter and more uniform contact between the heat-conducting groove and the surrounding structure. This helps reduce contact thermal resistance during heat conduction and improves heat transfer efficiency.

[0094] Thermally conductive adhesive not only fills the gaps inside the thermally conductive groove, but also expands the heat dissipation path to a certain extent. It can transfer heat from the thermally conductive groove to a wider area, making the heat distribution more uniform and preventing localized overheating. At the same time, the thermally conductive adhesive can also better integrate with other heat dissipation structures inside the laser (such as heat sinks and heat plates), further improving the overall heat dissipation effect.

[0095] High thermal conductivity thermal adhesives typically possess excellent flexibility and adhesion, enabling them to adapt to the thermal expansion and contraction changes of lasers under varying operating environments. When temperatures change, the thermal adhesive expands and contracts with structural deformation, maintaining good contact with the heat dissipation channels and other components, thus ensuring stable heat dissipation performance. Furthermore, the thermal adhesive also acts as a buffer, reducing the impact of external vibrations and shocks on the laser's internal structure and protecting critical components such as the emission aperture from damage.

[0096] In some embodiments, a refractive index gradient layer is provided at the boundary of the partition to smooth the difference in light emission angle between adjacent partitions.

[0097] Due to factors such as structure and drive current, different zones of a graded-gradient VCSEL laser exhibit varying luminescence characteristics. For instance, when the drive current is controlled independently for each zone, differences in current magnitude alter parameters such as carrier concentration and recombination rate, thereby affecting the emission direction and angle of the light. These characteristic differences between adjacent zones can lead to abrupt changes in the emission angle. If left unaddressed, this can degrade the overall beam quality of the laser, resulting in uneven beam distribution and hindering its applications in lighting, displays, and other fields.

[0098] Inside a laser, light propagates through different sections, creating a specific optical field distribution. Without a transition structure at the boundaries of these sections, the optical fields of adjacent sections will become discontinuous, leading to optical field mismatch. This not only reduces the coupling efficiency of light but also causes scattering and reflection during propagation, increasing energy loss. A refractive index gradient layer can serve as a transition medium, allowing for better coupling of the optical fields between adjacent sections and reducing the adverse effects of optical field mismatch.

[0099] When light propagates in different media, its direction of propagation changes according to Snell's law, and the refractive index is the key factor determining the direction of light propagation. In a graded-index layer, the refractive index changes continuously from one side of an adjacent section to the other. When light propagates from one section into the graded-index layer, the direction of light propagation also changes continuously and slowly due to the gradual change in refractive index. This continuous change in direction allows the exit angle of light to transition smoothly as it passes through the graded-index layer and enters an adjacent section, avoiding abrupt changes in the exit angle.

[0100] The graded-index layer can also achieve phase matching of the light fields of adjacent zones. Light emitted from different zones may have different phases, which can lead to optical interference and affect the intensity distribution and directionality of the beam. By adjusting the speed of light propagation (the refractive index is inversely proportional to the speed of light), the graded-index layer gradually makes the light propagating from adjacent zones more consistent in phase, thereby reducing the adverse effects of optical interference and making the light emission angle smoother.

[0101] By smoothing the difference in exit angle between adjacent zones, the graded-index layer significantly improves the beam quality of the laser. The smooth transition of the exit angle reduces the beam divergence angle, resulting in a more uniform and regular beam spot, thus improving the collimation and focusing of the beam. This is of great significance for applications requiring high beam quality, such as laser communication and laser processing. In laser communication, a high-quality beam can reduce signal loss and distortion during transmission, improving communication reliability and transmission distance; in laser processing, a uniform beam spot ensures processing precision and quality.

[0102] The graded-index layer reduces light scattering and reflection losses at the partition boundaries, allowing more light to propagate in the intended direction and improving the laser's energy utilization efficiency. Simultaneously, the improved optical field coupling efficiency reduces energy accumulation within the laser, mitigating thermal effects caused by excessive energy and further enhancing the laser's stability and reliability. This not only helps extend the laser's lifespan but also reduces its energy consumption, improving its economic efficiency.

[0103] In the fields of lighting and display, there are high requirements for the emission angle and beam uniformity of lasers. Gradient-index layers enable graded-index VCSEL lasers to better meet these application needs. For example, in laser lighting, a smooth emission angle makes the illumination range more uniform, reducing bright spots and dark areas; in laser displays, a high-quality beam and uniform beam can improve the clarity and color reproduction of the displayed image, enhancing the adaptability of the laser in different application scenarios.

[0104] 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.

[0105] 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 central area is an array of light-emitting holes, and the bottom is a cathode pad; The light-emitting aperture has several partitions, each partition having an independent anode pad, which can control the brightness of different areas through an external driving current to achieve a gradual change in brightness in the vertical direction.

2. The graded VCSEL laser according to claim 1, characterized in that, The array of light-emitting holes in the central region is distributed in a regular rectangular, circular, or hexagonal array.

3. A graded-variety VCSEL laser according to claim 1, characterized in that, Each section of the light-emitting hole is circular or polygonal in shape, and the shapes of different sections may be the same or different.

4. A graded VCSEL laser according to claim 1, characterized in that, The number of partitions is 2-10, and the area of ​​each partition may be the same or different.

5. A graded VCSEL laser according to claim 1, characterized in that, An insulating layer is provided between the cathode pad and the anode pad, and the insulating layer is made of silicon oxide or silicon nitride.

6. A graded VCSEL laser according to claim 1, characterized in that, The driving current is connected to each individual anode pad via a wire, the wire being made of the same or compatible conductive material as the anode pad.

7. A graded VCSEL laser according to claim 1, characterized in that, The vertical brightness gradient is achieved by controlling the magnitude of the driving current for different zones, and the magnitude of the driving current is positively correlated with the brightness of the corresponding zone.

8. A graded VCSEL laser according to claim 1, characterized in that, The partition edges are provided with reflective structures to improve light reflection efficiency and enhance luminescence.

9. A graded VCSEL laser according to claim 1, characterized in that, The array of light-emitting holes is surrounded by annular heat-conducting grooves for heat dissipation. The annular heat-conducting grooves are integrally formed with the laser substrate and are filled with thermally conductive adhesive with a high thermal conductivity.

10. A graded VCSEL laser according to claim 1, characterized in that, A refractive index gradient layer is provided at the boundary of the partition to smooth the difference in light emission angle between adjacent partitions.

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