Bottom-emitting vertical cavity surface emitting laser array with integrated directed beam diffuser

Abstract

A bottom-emitting vertical-cavity surface-emitting laser (VCSEL) wafer may include a VCSEL array comprising multiple VCSELs and an integrated optical element comprising multiple lens segments. The integrated optical element can guide a beam of light provided by the multiple VCSELs to a specific angular range to create a diffusion pattern using the beams provided by the multiple VCSELs. The surface of a first lens segment may be tilted to guide a beam of light from a first VCSEL at a first angle, and the surface of a second (adjacent) lens segment may be tilted to guide a beam of light from a second VCSEL at a second angle. The direction of the second angle relative to the surface of the VCSEL array may be opposite to the direction of the first angle relative to the surface of the VCSEL array.

Description

Technical Field

[0001] This disclosure generally relates to a vertical cavity surface-emitting laser (VCSEL) array and a bottom-emitting VCSEL array with an integrated directional beam diffuser. <Cross-reference to related applications>

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 014,483, filed April 23, 2020, entitled “Bottom-Emitting Vertical-Cavity Surface-Emitting Laser Array with Integrated Directional Beam Diffuser.” The disclosure of that prior application is considered part of the disclosure of this application and is incorporated herein by reference in its entirety. Prior Technology

[0003] VCSEL arrays can be used to illuminate various scenarios, such as for 3D sensing applications. Typically, a VCSEL array is paired with an external diffuser. The diffuser is used to extend the light supplied by the VCSEL's emitters into the field-of-view (FOV), sometimes also called the field of illumination (FOI). In the conventional arrangement of an external diffuser and VCSEL array, the diffuser diffuses the light from a given VCSEL across the entire FOV. In other words, the diffuser response does not vary from emitter to emitter within the VCSEL array. Summary of the Invention

[0004] In some embodiments, the bottom-emitting VCSEL wafer includes a VCSEL array comprising a plurality of VCSELs; and an integrated optical element comprising a plurality of lens segments, wherein the integrated optical element guides beams provided by the plurality of VCSELs to a specific angular range to create a diffusion pattern using the beams provided by the plurality of VCSELs, wherein the surface of a first lens segment of the plurality of lens segments is tilted such that beams from the first VCSELs of the plurality of VCSELs are guided at a first angle, wherein the surface of a second lens segment of the plurality of lens segments is tilted such that beams from the second VCSELs of the plurality of VCSELs are guided at a second angle, wherein the second lens segment is adjacent to the first lens segment, and wherein the direction of the second angle relative to the surface of the VCSEL array is opposite to the direction of the first angle relative to the surface of the VCSEL array, and wherein the beams from the plurality of VCSELs will pass through only one of the plurality of lens segments.

[0005] In some embodiments, the optical device includes a VCSEL array comprising a plurality of VCSELs; and an integrated optical element comprising a plurality of lens segments, wherein the integrated optical element guides beams provided by the plurality of VCSELs to a specific angular range to create a diffusion pattern using the beams provided by the plurality of VCSELs, wherein the lens segments of the plurality of lens segments guide beams from the VCSELs among the plurality of VCSELs at corresponding specific angles associated with creating the diffusion pattern, and wherein the surfaces of two adjacent lens segments of the plurality of lens segments are tilted such that beams from two corresponding VCSELs of the plurality of VCSELs are guided at angles having opposite directions relative to the surface of the VCSEL array.

[0006] In some embodiments, the optical device includes a VCSEL array comprising a plurality of VCSELs; and an integrated optical element comprising a plurality of lens segments, wherein the integrated optical element guides beams provided by the plurality of VCSELs to a specific angular range to create a diffusion pattern using the beams provided by the plurality of VCSELs, wherein light from the plurality of VCSELs exists in a portion of the diffusion pattern, said portion being smaller than the whole diffusion pattern, and wherein the surfaces of said lens segments are tilted in alternating directions such that beams from two or more corresponding VCSELs are guided at alternating angles relative to the surface of the VCSEL array. Simple Explanation of the Diagram

[0007] [Figure 1] is a schematic diagram of an example optical device including the emitter array and integrated directional beam diffuser described herein.

[0008] [Figure 2] is an illustrative example of the outline of a bat wing, which can be achieved through the appropriate design of the optical device described herein.

[0009] [Figure 3] is a graph showing the combined relative intensity of the output of the optical device described herein as a function of angle, and a graph showing the relative intensity of a single emitter as a function of angle.

[0010] [Figure 4] is a diagram showing an exemplary distribution of the transmitter, which is designed to guide the beam to various angles associated with the angle that produces the composite intensity shown in Figure 3.

[0011] [Figure 5] is a diagram showing an example of the distribution of aiming directions of the transmitters in a two-dimensional transmitter array included in the optical device described herein.

[0012] [Figures 6A to 6C] are graphs showing the distribution of intensity relative to angle for an example transmitter array associated with the example shown in Figure 5.

[0013] [Figure 7] shows an example of a one-dimensional slice of intensity versus angle as shown in Figure 6A, in the case where the transmitter near the center of the example transmitter array is a dead transmitter.

[0014] [Figure 8] is a schematic diagram illustrating the example optical device described herein, wherein the integrated directional beam diffuser includes a lens segment as an integral lens.

[0015] [Figure 9] is a schematic diagram illustrating an example optical device described herein, wherein the integrated directional beam diffuser includes a lens segment as a lens portion.

[0016] [Figure 10] is a diagram illustrating an example of an alternative design for an integrated directional beam diffuser that provides the same intensity-to-angle profile as the integrated directional beam diffuser shown in the optical device of Figure 1.

[0017] [Figures 11 and 12] are schematic diagrams illustrating an example of a simplified two-dimensional layout for beam control provided by the integrated directional beam diffuser described herein.

[0018] [Figure 13] is a schematic diagram of a flip-chip mounted optical system including the integrated directional beam diffuser described herein.

[0019] [Figures 14A and 14B] are diagrams illustrating an exemplary arrangement of the lens segments that reduces abrupt changes in the lens segment profile on the integrated optics described herein.

[0020] [Figures 15 and 16] are diagrams illustrating an exemplary optical device in which the transmitters of transmitter array 102 are connected in groups that vary sequentially across the transmitter array.

[0021] [Figures 17 and 18] are schematic diagrams showing an example optical device, wherein the connection of the transmitter assembly is located on one side of the optical device. Implementation

[0022] The following detailed description refers to the accompanying drawings. The same reference numerals in different drawings may identify the same or similar elements.

[0023] As described above, conventional diffusers are discrete components positioned at a specific distance from a light source (e.g., a VCSEL) and used to diffuse light from the source across the entire field of view (FOV). This arrangement and function can be advantageous when the light source is single-mode or few-mode, resulting in interference speckles (also known as speckle). However, some emitters, such as VCSELs, may have lateral modes that vary on picosecond (or shorter) timescales, which significantly reduces speckle. This means that extensive diffusion of light from a given VCSEL in a VCSEL array is not required to obtain a sufficiently smooth pattern.

[0024] Furthermore, diffusers can be either diffracting or refractive. Both types of diffusers are affected by increasing VCSEL divergence, potentially resulting in an FOV efficiency of only about 70% to 80%. Besides FOV efficiency, light can be reflected by the diffuser's incident surface (e.g., a polymer surface) or its exit surface (e.g., a glass surface), neither of which typically lacks an anti-reflective (AR) coating (due to the difficulty in depositing and fixing AR coatings). Without these AR coatings, efficiency is further reduced (e.g., by about 8%). Additionally, diffusers require micron or submicron scale features that are difficult or impossible to fabricate using photolithography, requiring imprints from a mold. Molds can be significantly more expensive than photomasks and are unsuitable for integration with VCSEL arrays that can vary with the product. Furthermore, for diffracting diffusers, unwanted extraneous light often appears at the center of the diffusion pattern when viewed from the "zero order" direction. For refractive diffusers, zero-order diffraction may not be a problem, but parasitic reflections may occur at certain angles, reducing efficiency. This problem becomes more pronounced at the interface where light enters air from a material with a high refractive index (e.g., a semiconductor material). For these reasons, using conventional discrete diffusers may not be optimal in applications where VCSELs are used as the light source.

[0025] Some embodiments described herein provide a VCSEL wafer with a bottom-emitting VCSEL array having an integrated optical element (referred to herein as the integrated optical element) that functions as a directional beam diffuser. In some embodiments, the integrated optical element includes multiple lens segments that collectively generate a diffusion pattern from the beam supplied by the VCSELs of the VCSEL array (e.g., such that the total intensity from all VCSELs angularly simulates the output of a conventional diffuser). In some embodiments, the integrated optical element generates the diffusion pattern by guiding the beam supplied by the VCSELs within a specific angular range. In some embodiments, the beam from a given VCSEL passes through only one lens segment of the integrated optical element. In some embodiments, the lens segment guides the beam from a given VCSEL at a specific angle associated with generating the diffusion pattern. In some embodiments, the light from a given VCSEL appears only in a portion of the diffusion pattern. That is, the light from a given VCSEL does not diffuse across the entire diffusion pattern (as is the case with a conventional diffuser).

[0026] As described in further detail below, VCSEL arrays with integrated optics overcome the aforementioned drawbacks of conventional diffusers. In this way, the functions of a discrete diffuser and a VCSEL array can be combined into a compact chip, while also improving the efficiency of the optical system. Furthermore, chips with integrated optics enable independent illumination of different regions, which may be advantageous for some optical systems, such as indirect time-of-flight systems requiring high power to illuminate objects at greater distances.

[0027] Figure 1 is a schematic diagram of an example optical device 100 including an emitter array 102 and integrated optical elements 106. The optical device 100 may be, for example, a bottom-emitting VCSEL wafer.

[0028] Emitter array 102 is an array of emitters that provides light (e.g., beam 110), from which integrated optical elements 106 generate a diffusion pattern. For example, as shown in FIG1, emitter array 102 may include a plurality of emitters 104, each emitter providing a corresponding beam 110. In some embodiments, emitter array 102 is a planar array having oxide trenches defining the plurality of emitters 104. In some embodiments, emitter array 102 is a bottom-emitting VCSEL array including a plurality of bottom-emitting VCSELs (i.e., the emitters 104 of emitter array 102 can emit light through the substrate side of emitter array 102). In some embodiments, emitter array 102 is a one-dimensional (1D) array of emitters 104. In some embodiments, emitter array 102 is a two-dimensional (2D) array of emitters 104. In some embodiments, emitter array 102 includes at least about 40 emitters 104 (e.g., emitter array 102 may include several hundred emitters). In some implementations, the number of emitters 104 can be selected to create a smooth intensity-to-angle profile (e.g., compared to an array of different points in the far field). Notably, this design also enables independent illumination of different portions of the FOV.

[0029] The integrated optical element 106 is a component that creates a diffusion pattern from the light beam 110 provided by the emitter 104 of the emitter array 102. As shown in FIG1, the integrated optical element 106 may include a plurality of lens segments 108. In some embodiments, the integrated optical element 106 is integrated with the emitter array 102. That is, the integrated optical element 106 is not a discrete or external diffuser. Instead, the integrated optical element 106 is integrated with the emitter array 102 in a single wafer. For example, the plurality of lens segments 108 may be patterned on a substrate (e.g., a gallium arsenide (GaAs) substrate) of the emitter array 102. In some embodiments, the optical element 106 and the emitter array 102 may be monolithically integrated into a wafer comprising a plurality of optical devices 100. In some embodiments, the integrated optical element 106 may be formed on a substrate. In some embodiments, the integrated optical element 106 may be formed in the substrate of the emitter array 102. Therefore, in some embodiments, the lens segments 108 are formed on the outer surface of the optical device 100. In some embodiments, the optical element 106 may have an anti-reflective coating deposited on its top surface.

[0030] In some embodiments, the slope of a given lens segment 108 of the integrated optics 106 (e.g., relative to the surface of the emitter array 102) can be selected to guide the beam 110 at a specific angle. Thus, the slope of the lens segment 108 of the integrated optics 106 can be selected so that the integrated optics 106 produces a desired diffusion pattern from the beam 110 provided by the emitter 104 of the emitter array 102.

[0031] In some embodiments, the surface of the lens segment 108 of the integrated optical element 106 may be planar (e.g., a surface with a linear slope). A lens segment 108 with a tilted planar surface can provide guidance for the beam 110, but cannot reduce the divergence of the beam 110. In some embodiments, the surface of the lens segment 108 of the integrated optical element 106 may be curved (e.g., the surface may have a non-linear slope, as shown in FIG. 1). In some embodiments, the curvature of the surface of the lens segment 108 can be used to reduce the divergence of the beam 110 passing through the lens segment 108, which is beneficial at, for example, relatively steep angles (e.g., at the edges of a diffusion pattern where the beam can exit at an angle of 20 to 60 degrees with respect to the normal and the surface can be tilted nominally 7 to 14 degrees relative to the horizontal direction, improving the sharpness of the intensity against the angular profile). In some embodiments, the radius of curvature of a given lens segment 108 may range from approximately 180 micrometers (µm) to approximately 450 µm (e.g., it may range from approximately ±1 µm to approximately ±5 µm to obtain reasonable tolerances for misalignment). In some embodiments, the slope of the surface of lens segment 108 can be selected to guide the light beam 110 passing through lens segment 108 in a desired direction. In some embodiments, the surface type of a given lens segment 108 (e.g., curved, flat) can be selected to selectively reduce the divergence of the light beam 110 passing through a given lens segment 108. In some embodiments, reducing the divergence of the light beam 110 illuminating the edge of the FOV can improve the sharpness of the edge of the convergence profile of the diffusion pattern generated by the integrated optics element 106. In some embodiments, lens segments 108 may each correspond to the same reference lens segment, or may each correspond to a set of two or three reference lens segments.

[0032] In some embodiments, the spacing (e.g., center-to-center distance) between a given pair of lens segments 108 is in the range of approximately 30 µm to approximately 60 µm and is intended to match the spacing of the transmitters. This spacing is much smaller than that of a complete (circular) lens, which can be 100 µm to 200 µm. In some embodiments, the size of the coverage area of ​​the integrated optics 106 is matched to or smaller than the size of the coverage area of ​​the transmitter array 102. That is, in some embodiments, the coverage area of ​​the integrated optics 106 is no larger than the coverage area of ​​the transmitter array 102.

[0033] As shown in Figure 1, in operation, the emitter 104 of the emitter array 102 emits beams 110 through the integrated optics 106, such that each beam 110 passes through a corresponding lens segment 108. In some embodiments, as shown in Figure 1, the optical device 100 is designed such that each beam 110 passes through a different lens segment 108 of the integrated optics 106 (i.e., no two beams 110 pass through the same lens segment 108). Alternatively, in some embodiments, the optical device 100 may be designed such that two or more beams 110 pass through a given lens segment 108 of the integrated optics 106.

[0034] In some implementations, the lens segment 108 of the integrated optics 106 guides the light beam 110 to a specific angular range to create a diffusion pattern using the light beam 110. To generate a diffusion pattern, a given lens segment 108 guides the light beam 110 from one or more emitters 104 at a specific angle (e.g., the specific angle depends on the slope of the surface of the given lens segment 108). As shown in FIG1, the light beam 110 provided by the emitter 104 on the left side of the emitter array 102 can be guided in a generally leftward direction associated with generating a diffusion pattern. For example, as shown in FIG1, the light beam 110 provided by the emitter 104 on the right side of the emitter array 102 can be guided in a generally rightward direction associated with generating a diffusion pattern. As shown in FIG1, the light beam 110 provided by the emitter 104 near the center of the emitter array 102 can be guided in a generally straight direction associated with generating a diffusion pattern. As a result, as shown in FIG1, the light from a given emitter 104 exists only in a portion of the diffusion pattern generated by the integrated optics 106 (i.e., the light from a given emitter does not exist across the entire diffusion pattern).

[0035] It is worth noting that, as shown in Figure 1, the beam 110 from a given emitter 104 may pass through only one lens segment 108. In some embodiments, the optical device 100 may be designed such that the synthesized output beam of the optical device 100 simulates the output beam of a conventional diffuser. That is, in some embodiments, the diffusion pattern created by the integrated optical element 106 can simulate the diffusion pattern of the aforementioned conventional external diffuser. In some embodiments, the optical device 100 is designed such that the angle of the focusing intensity relative to the diffusion pattern minimizes the appearance of spots from the individual emitters 104 in the diffusion pattern (e.g., such that the intensity varies between the inner and outer angles of the diffusion pattern with an oscillation of less than about 20%). In some embodiments, the optical device 100 is designed to maximize the power concentrated within the FOV. To increase the power within a particular FOV, the edges of the profile need to be sharp relative to the angle. An optical device 100 designed with a smaller emitter (e.g., 4µm to 16µm aperture diameter) and an optimal radius of curvature (e.g., 150µm to 380µm for GaAs substrates, typically 1.4 to 2.5 times the substrate thickness) will better reduce divergence and result in a sharper, more efficient profile when pointed towards the edge of the field of view (FOV). To achieve a smooth profile, the radius of curvature and individual divergence may need to be increased for emitters pointing towards the center of the FOV. Thicker substrates (e.g., thickness greater than 400 micrometers) and larger radii of curvature further reduce divergence, but require further separation of the emitters, which increases wafer cost and may result in a far-field profile that is scattered into spots rather than a continuous beam.

[0036] As stated above, Figure 1 is provided as an example. Other examples may differ from those described with respect to Figure 1. Furthermore, the number and arrangement of components shown in Figure 1 are provided as examples. In practice, there may be more components, fewer components, different components, or different arrangements of components than shown in Figure 1.

[0037] In some embodiments, the optical device 100 is designed such that the diffusion pattern has a high intensity (e.g., approximately 2 to 4 times the center intensity) at a relatively large angle within a desired field of view (FOV), e.g., from approximately 50 degrees to approximately 120 degrees, to achieve a so-called "bat wing" profile. Figure 2 is an illustrative example of a bat wing profile achievable through a suitable design of the optical device 100. Figure 2 is provided as an example, and other examples may differ from those described with respect to Figure 2.

[0038] Figure 3 is a diagram showing the composite relative intensity to angle (far field) of the output of the optical device 100 after the integrated optics 106 of all the transmitters 104 in the example transmitter array 102, and the relative intensity to angle after the integrated optics 106 of a single transmitter 104 in the example transmitter array 102. As shown in Figure 3, in the operation of the optical device 100, the beam 110 of a single transmitter 104 is directed in a specific direction (indicated by the associated lens segment 108). Other beams 110 emitted by the other transmitters 104 of the transmitter array 102 are similarly directed (at specific angles indicated by their associated lens segments 108), such that the beams 110 provided from the transmitters 104 produce a composite relative intensity to angle. That is, the synthesis of the intensity profile associated with each transmitter 104 of example 102 will result in the composite relative intensity to angle profile shown in Figure 3.

[0039] Figure 4 is a diagram illustrating an exemplary distribution of emitters 104, which are designed to guide beams 110 at various angles associated with the angles producing the composite intensity shown in Figure 3. In the example shown in Figure 4, emitter array 102 has 19 emitters 104, and lens segment 108 integrating optical element 106 guides beams 110 to specific angles given by the distribution shown in Figure 4. In some embodiments, as shown in Figure 4, the number of emitters 104 aimed toward the center of emitter array 102 (e.g., at angles with smaller absolute values) is relatively small. However, the number of emitters 104 aimed toward the center of emitter array 102 can be not too low, such that a single beam 110 appears in the far field. In some embodiments, as shown in Figure 4, the number of emitters 104 aimed at angles near the edge of the FOV (e.g., at angles with higher absolute values) can be relatively high (e.g., increasing the intensity near the edge of emitter array 102 to create a diffusion pattern with a batwing profile). As mentioned above, Figures 3 and 4 are provided as examples. Other examples may differ from those described with respect to Figures 3 and 4.

[0040] It is worth noting that the examples in Figures 3 and 4 are associated with a one-dimensional (1D) transmitter array 102, but similar principles can be applied to the case of a 2D transmitter array 102. Figure 5 shows an example diagram of the aiming direction distribution of the transmitters 104 in a 2D transmitter array 102 (e.g., an array of 328 transmitters 104 is shown in Figure 5). In some embodiments, as shown in Figure 5, the distribution of aiming directions may have a honeycomb pattern (e.g., instead of a square grid) at the center of the far field (e.g., away from the edge of the far field). In some embodiments, the honeycomb pattern allows for uniform coverage of the circular far field of a single transmitter 104. It is important to note that the honeycomb pattern shown in Figure 5 indicates the distribution of the aiming directions of the transmitters 104 provided by the integrated optics element 106 and is independent of the spatial distribution of the transmitters 104. That is, the distribution shown in Figure 5 does not represent the physical layout of the transmitters 104 in the transmitter array 102.

[0041] Figures 6A through 6C illustrate the intensity versus angle distribution of the example transmitter array 102 associated with Figure 5. Figure 6A shows the 2D intensity versus angle for all transmitters 104 of the 2D transmitter array 102. Notably, the intensity is higher near the edges of the intensity distribution (e.g., as shown through relatively darker areas). Figure 6B shows the 2D intensity versus angle for a single transmitter 104 of the 2D transmitter array 102 (at the same scale as Figure 6A). Here, each transmitter 104 of the example transmitter array 102 will have similar intensities but will point to different angles (e.g., different locations in Figures 6A and 6B). The combination of the intensities associated with all transmitters 104 will result in the distribution shown in Figure 6A. Figure 6C shows an example of a 1D “slice” along the first axis (θY axis shown in Figure 5) at various values ​​(e.g., 0 degrees, 16 degrees, and 25 degrees) through the intensity versus angle distribution shown in Figure 6A along the second axis (θX axis shown in Figure 5). As shown in Figures 6A and 6C, the diffusion pattern created by the integrated optical element 106 in the 2D implementation can have a bat wing profile (e.g., at a given “slice” of the distribution).

[0042] One consideration for integrating the optical element 106 is that it can still operate even if the transmitter 104 fails. The “failed” transmitter 104 can be, for example, a transmitter 104 with a power amount less than a threshold, a transmitter 104 with no power, a transmitter 104 with much less power than its neighboring transmitters 104, etc. Figure 7 shows an example of an intensity versus angle slice as shown in Figure 6A when the transmitter 104 near the center of the example transmitter array 102 is a failed transmitter. Therefore, Figure 7 illustrates the tolerance of the optical device 100 to the presence of a failed transmitter 104 in the transmitter array 102. As shown in Figure 7, the failed transmitter 104 near the center of the 2D transmitter array 102 only reduces the intensity by about 15%, meaning that the optical device 100 can still provide the desired function in most cases. It is worth noting that the example shown in Figure 7 is an extreme case where the failed transmitter 104 has zero power. In practice, the failed transmitter 104 can have some power, meaning that the intensity reduction will be less severe in some cases.

[0043] As described above, Figures 5, 6A through 6C, and 7 are provided as examples. Other examples may differ from those described in Figures 5, 6A through 6C, and 7.

[0044] In some embodiments, as described above, the surface of lens segment 108 may be curved to reduce the divergence of beam 110 (e.g., allowing for better confinement of optical power within the field of view). Figure 8 is a schematic diagram showing lens segment 108 with a radius of curvature r (e.g., formed on the substrate of emitter array 102), through which beam 110 from emitter 104 passes at an angle θ (relative to the horizontal direction) and exits. However, if the curvature is too strong, the final tilt of beam 110 may be sensitive to errors (shown as x0 in Figure 8) in deviating from the center of the lens. For example, if the alignment tolerance is + / - 2 micrometers, for a radius of curvature of 200 micrometers, a beam nominally pointing 30 degrees away from the vertical direction (perpendicular to the substrate surface) may deviate by + / - 2 degrees, and the error will increase as the radius of curvature decreases. Due to the limitation of the radius of curvature, as described above, the size of the complete (circularly symmetrical) lens can be large, and lens segments are preferred. Furthermore, tight curvature will result in uneven illumination. In some implementations, to tolerate misalignment up to a few micrometers (e.g., an error in x0 instead of the target value of x0) and to maintain angular profile centering (e.g., within a few degrees), the radius of curvature r can be between approximately 180 micrometers and approximately 450 micrometers (e.g., when lens segment 108 is formed in GaAs, which is the common substrate of the VCSEL). For radii of curvature in such a range, the offset x0 from the center of lens segment 108 to beam 110, tilting the beam by approximately 30 to 40 degrees, is on the order of tens of micrometers. It is noteworthy that when lens segment 108 is used as a whole lens (e.g., a radially symmetrical lens as shown in FIG. 8) for each emitter 104, the emitter-to-emitter spacing is limited by the spacing plens between adjacent lenses, which can be, for example, 100 micrometers to 200 micrometers. This limitation can result in a significant waste of space between emitters 104 and lead to large and expensive dies. Therefore, in some implementations, lens segment 108 can be a portion of the entire lens area (e.g., a few percent). Therefore, using this lens segment 108 can reduce the size and cost of the optical device 100.

[0045] Figure 9 is a schematic diagram illustrating an example optical device 100, which includes lens segments 108 (e.g., segments of a radially symmetric lens, rather than the entire radially symmetric lens) as part of a lens. In the example shown in Figure 9, each emitter 104 is arranged below the lens segment 108 to guide the beam 110 and partially reduce beam divergence. Here, the lens segment 108 is arranged such that the spacing pe between the emitters 104 can be limited by the size of the beam 110 at the lens segment 108 rather than the size of the entire lens. It is noteworthy that because the emitter array 102 is generally relatively small (e.g., about 1 millimeter in size) compared to the scene illuminated by the optical device 100 (e.g., which can have a size on the order of hundreds of millimeters to several meters (m)), the spatial position of the emitters 104 on the wafer does not change the observed intensity versus angle relationship. Therefore, the lens segments 108 can be spatially rearranged in any order. In some embodiments, the spatial configuration of the lens segments 108 is configured to improve the manufacturability (e.g., yield and reproducibility) of the integrated optical element 106. In some embodiments, the spatial arrangement of lens segments 108 is configured to reduce the frequency or height of transitions between adjacent lens segments. In some embodiments, the spatial arrangement of lens segments 108 is configured to reduce the impact of power loss from potential fault forms (e.g., adjacent emitter failure, edge failure, crystal misalignment, etc.). As further illustrated in FIG9, in some embodiments, lens segments 108 are recessed by a spacer distance from the top surface of the integrated optical element 106 at the periphery (e.g., the edge of the grain) of the emission region of the optical device 100. Here, the lens segments 108 recessed from the top surface by the spacer distance can be used to protect the surface of the lens segments 108 from damage.

[0046] As mentioned above, Figures 8 and 9 are provided as examples. Other examples may differ from those described in Figures 8 and 9.

[0047] In practice, different designs of the lens segment 108 of the integrated optical element 106 can be used to provide the same intensity-to-angle profile. For example, the design of the lens segment 108 of the integrated optical element 106 shown in FIG. 10 can provide the same intensity-to-angle profile as the lens segment 108 of the integrated optical element 106 shown in FIG. 1. It is worth noting that FIG. 10 is a schematic diagram illustrating an example of an alternative design that provides the same intensity-to-angle profile as the integrated directional beam diffuser shown in the optical device of FIG. 1 when both electrodes are excited. When either of the two electrodes is excited, the intensity profile is illuminated relative to the central or outer portion of the angle. It is noteworthy that the design shown in FIG. 1 causes the beam 110 closer to the edge of the emitter array 102 to be more tilted than the beam 110 closer to the center of the emitter array 102. In contrast, the design shown in FIG. 10 causes the beam 110 on the left side of the emitter array 102 to be less tilted than the beam 110 on the right side of the emitter array 102.

[0048] In some embodiments, beams 110 with relatively small tilt can be grouped under one contact of the emitter array 102, while beams 110 with relatively large tilt can be grouped under another contact of the emitter array 102 (e.g., individual anodes or cathodes). That is, in some embodiments, a first group of emitters 104 of the emitter array 102 is connected to a first contact 112a of the optical device 100, and a second group of emitters 104 of the emitter array 102 is connected to a second contact 112b of the optical device 100, as shown in FIG10. In this case, as further shown in FIG10, the integrated optical element 106 can be designed to guide the beams 110 from the first group of emitters 104 toward the center of the diffusion pattern, and can guide the beams 110 from the second group of emitters 104 toward one or more edges of the diffusion pattern. In some implementations, one or more transmitters 104 in the first group of transmitters 104 are located at the edge of the transmitter array 102, and one or more transmitters 104 in the second group of transmitters 104 are located at the edge of the transmitter array 102, which improves the addressability of the transmitter group 104.

[0049] Figure 11 is a diagram illustrating an example of a simplified 2D spatial layout (e.g., a 9×9 layout) for beam control provided by the integrated optics element 106. In Figure 11, each emitter 104 of the emitter array 102 is represented by a box, and the associated arrows indicate the tilt direction provided by the integrated optics element 106 (viewed from directly above the integrated optics element 106). The dots in the center box represent beams 110 pointing directly out of the plane of Figure 11. In Figure 11, the lens segment 108 closer to the center of the emitter array 102 provides a relatively smaller tilt than the lens segments 108 closer to the edge of the emitter array 102. This design is consistent with the design of the integrated optics element 106 shown in Figure 1.

[0050] Another layout is shown in Figure 12. In Figure 12, the lens segment 108 is arranged such that the beam 110 with a relatively small tilt is closer to the corner of the emitter array 102 (e.g., the upper left corner of the emitter array 102), rather than closer to the center of the emitter array 102 as in the case of Figure 11. One advantage of the design of the integrated optics 106 associated with Figure 12 is that the addressing beam 110, which is directed closer to the center of the field of view (FOV), is simplified compared to doing so in Figure 11 (e.g., because the emitter 104, which is aimed closer to the center of the FOV, is located at the edge of the emitter array 102). For example, the optics 100 can be a flip-chip mounted on a base, and the traces leading to the edge of the optics 100 can be routed on a single plane of the base. In contrast, in the design shown in Figure 11, either the optics 100 requires overlapping traces to access the emitter 104, which is closer to the center, or the base requires traces or vias—both of which increase the cost and complexity of the optics 100 or the base. Another possible arrangement (not shown) is to arrange lens segment 108 such that transmitters 104 aimed closer to the center of the FOV are located at multiple positions along the perimeter of transmitter array 102 (e.g., at corners). In this arrangement, failure of multiple adjacent transmitters 104 may not result in a significant loss of functionality (e.g., because not all transmitters 104 aimed closer to the center will cluster together). It is worth noting that the layouts in Figures 11 and 12 can be used to illuminate the FOV or sub-regions of the FOV.

[0051] Figure 13 is a schematic diagram illustrating a flip-chip mounted optical device 100 including an integrated optical element 106. In some embodiments, as shown in Figure 13, an augmented reality coating is formed on the top surface of the optical device 100 to reduce reflections on the top surface of the optical device 100.

[0052] As described above, Figures 10 to 13 are provided as examples. Other examples may differ from those described in Figures 10 to 13.

[0053] The integrated optical element 106 described above is relatively more efficient than conventional (discrete) diffusers. For example, the divergence of a given beam 110 can be reduced to produce a sharper edge in the intensity-to-angular profile, thereby improving FOV efficiency (e.g., by approximately 7%). Furthermore, the augmented reality coating can be more easily formed and maintained on the optical device 100 (e.g., compared to conventional diffusers). Conventional diffusers are typically polymers attached to glass and stamped to form a refractive pattern. Typically, the augmented reality coating is a thin film of dielectric material, such as a metal oxide or glass, or a multilayer stack of metal oxides or glasses, with a thickness equivalent to a wavelength (a fraction of a micrometer). Such a thin dielectric film does not adhere well to the polymer, which may stretch more rapidly with increasing temperature, causing the film to break. However, the AR coating material is compatible with semiconductors. The reduction in reflection provided by the AR coating can provide a further increase in efficiency (e.g., approximately 4% to 8%, depending on whether the conventional diffuser is coated on the glass substrate side). It is worth noting that some (e.g., approximately 3%) may originate from absorption by the substrate. However, even with this absorption, the overall improvement in efficiency can be significant (e.g., approximately 12%).

[0054] In some embodiments, the arrangement of the lens segments 108 can be selected to simplify the manufacture of the optical device 100. For example, the arrangement of the lens segments 108 can be selected to reduce or eliminate abrupt changes in the contours of the lens segments 108 on the integrated optical element 106. Figures 14A and 14B are diagrams illustrating example arrangements of the lens segments 108 that reduce abrupt changes in the contours of the lens segments 108 on the integrated optical element 106 (e.g., compared to the design shown in Figure 1). It is noteworthy that in the design shown in Figure 1, the transition between a given pair of adjacent lens segments 108 (most readily visible at the leftmost and rightmost ends of the integrated optical element 106) is a vertical step. In some embodiments, for ease of manufacture, the arrangement of the lens segments 108 can be selected as shown in Figure 14A, such that, for example, the beams 110 on the two leftmost adjacent lens segments 108 of the integrated optical element 106 point in substantially opposite directions (e.g., to the left and to the right), rather than both pointing in substantially the same direction (e.g., to the left, as shown in the design of Figure 1). Similarly, the beams 110 on the two adjacent lens segments 108 on the far right of the integrated optical element 106 point in roughly opposite directions (e.g., to the left and to the right), instead of both pointing in roughly the same direction (e.g., to the right, as shown in FIG1). Here, by comparing FIG14A and FIG1, it can be seen that there are no abrupt steps between these adjacent lens segments in the integrated optical element 106 with this arrangement, thereby simplifying the manufacture of the optical device 100 (e.g., because abrupt changes in the contour of the integrated optical element 106 may be difficult to manufacture).

[0055] Therefore, in some embodiments, the surface of lens segment 108 may be tilted in alternating directions such that the beam 110 from the emitter 104 of emitter array 102 is guided at alternating angles relative to the surface of emitter array 102. In other words, in some embodiments, the surfaces of two adjacent lens segments 108 may be tilted such that the beams 110 from the two emitters 104 of emitter array 102 are guided at angles having opposite directions relative to the surface of emitter array 102. As a specific example, the surface of the first lens segment 108 may be tilted such that the beam 110 from the first emitter 104 is guided at a first angle, and the surface of the second lens segment 108 may be tilted such that the beam 110 from the second emitter 104 is guided at a second angle. In this example, the second lens segment 108 is adjacent to the first lens segment 108, and the direction of the second angle relative to the surface of emitter array 102 is opposite to the direction of the first angle relative to the surface of emitter array 102.

[0056] Additionally, as shown in Figure 14B, in some embodiments, the transition between regions from which the beam 110 exits (e.g., regions near the edges of lens segments 108 where the beam 110 is not incident) can be smoothed, further reducing abrupt profile changes between lens segments 108. Because these regions do not have optical function, they can be adjusted according to manufacturing requirements. As further shown in Figure 1B, in some embodiments, the transition to higher platforms outside the lens segments 108 can also be smoothed. It is worth noting that the illustrations shown in Figures 14A and 14B are for 1D designs, but these techniques can be similarly applied to 2D designs. In some embodiments, by arranging the lens segments 108 to reduce steps and smooth the profile of the integrated optics 106, a more compact emitter design can be achieved (e.g., such arrangement or smoothing would require relatively more grain area for step transitions compared to a design without such arrangement or smoothing). It is worth noting that such arrangement may be unnecessary for relatively small angular variations (e.g., ±5 degrees) because abrupt steps may not exist in the profile of the integrated optics 106 in these regions.

[0057] As described above, Figures 14A and 14B are provided as examples. Other examples may differ from those depicted in Figures 14A and 14B.

[0058] In some implementations, the transmitters 104 across the transmitter array 102 can be connected in groups, with these groups varying sequentially across the transmitter array 102. This configuration can be used, for example, to enable a scene to be scanned from a negative angle to a positive angle.

[0059] Figure 15 is a diagram illustrating an exemplary optical device 100, in which emitters 104 of a 2D emitter array 102 are connected in groups, these groups varying sequentially across the emitter array 102. In Figure 15, the emitter guide angles in the x-direction are indicated along the top of the optical device 100. As shown, the guide angles in the x-direction alternate between negative and positive angles to minimize vertical transitions in the profile of the integrated optical element 106 as described above. Furthermore, the emitter guide angles in the y-direction are indicated along the left side of the optical device 100. As shown, the guide angles in the y-direction alternate between negative and positive angles to minimize vertical transitions in the profile of the integrated optical element 106 as described above. In the example shown in Figure 15, the emitters 104 are connected by a first metal layer (shown in gray) to form four groups of guide angles spanning from -24 degrees to -15 degrees (group 1), -12 degrees to -3 degrees (group 2), +3 degrees to +12 degrees (group 3), and +15 degrees to +24 degrees (group 4). Therefore, in some embodiments, the transmitters 104 in the transmitter array 102 can be connected such that the guide angles provided by the plurality of lens segments 108 change sequentially across the transmitter array 102 in a particular direction (e.g., the x-direction and / or the y-direction).

[0060] In some embodiments, the optical device 100 shown in FIG. 15 may include a second metal layer to provide a heat dissipation pad, an example of which is shown in FIG. 16. In some embodiments, as shown in FIG. 16, the second metal layer may be formed on a dielectric layer (e.g., to prevent adjacent emitter groups 104 from short-circuiting together). In some embodiments, this design allows flip-chip bonding to a substrate and connection to a driver.

[0061] In some embodiments, the optical device 100 may be designed such that the connection of the group of emitters 104 is arranged on one side of the optical device 100. In some embodiments, this arrangement may, for example, implement the driver connection only on one side of the optical device 100. Figure 17 is a diagram illustrating an example optical device 100 in which the connection of the emitter group 104 is on one side of the optical device 100. In Figure 17, the emitter guide angle in the x-direction is indicated along the top of the optical device 100. As shown, the guide angle in the x-direction alternates between negative and positive angles to minimize the vertical transition in the profile of the integrated optical element 106 as described above. Furthermore, the emitter guide angle in the y-direction is indicated along the left side of the optical device 100. As shown, the guide angle in the y-direction alternates between negative and positive angles to minimize the vertical transition in the profile of the integrated optical element 106 as described above. In the example shown in Figure 17, the transmitter 104 is associatedly connected via a first metal layer (shown in gray) to form four groups of guide angles spanning from -24 degrees to -15 degrees (group 1), from -12 degrees to -3 degrees (group 2), from +3 degrees to +12 degrees (group 3), and from +15 degrees to +24 degrees (group 4).

[0062] As shown in Figure 17, a first metal layer can be formed to provide electrical connections to all four groups from one side of the optical device 100. It is noteworthy that in the example shown in Figure 17, connections to groups 1 and 2 are entirely formed on the first metal layer, while connections to groups 3 and 4 are only partially formed on the first metal layer. In this example, the connections to groups 3 and 4 are completed on a second metal layer, as shown in Figure 18. In some embodiments, as further shown in Figure 18, the second metal layer can further provide a heat dissipation pad for the optical device 100. In some embodiments, as shown in Figure 18, the second metal layer can be formed on a dielectric layer (e.g., to prevent adjacent emitter groups 104 from short-circuiting together). Here, the dielectric layer includes vias to allow connections to groups 3 and 4 to be completed. In some embodiments, this design allows flip-chip bonding to the substrate and connection to the driver.

[0063] As described above, Figures 15 to 18 are provided as examples. Other examples may differ from those described in Figures 15 to 18.

[0064] The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. Modifications and variations can be made based on the foregoing disclosure, or modifications and variations can be derived from practice of the embodiments. Furthermore, any embodiments described herein can be combined unless the foregoing disclosure expressly provides reasons why one or more embodiments may not be combined.

[0065] Even though specific combinations of features are referenced in the request and / or disclosed in the specification, these combinations are not intended to limit the disclosure of various embodiments. In fact, many of these features can be combined in ways not specifically described in the request and / or disclosed in the specification. Although each dependent request listed below may directly refer to only one request, the disclosure of various embodiments includes combinations of each dependent request with each other request in that group of requests.

[0066] Unless explicitly stated otherwise, the elements, actions, or instructions used herein should not be construed as critical or necessary. Furthermore, as used herein, the articles “a” and “one” are intended to include one or more items and may be used interchangeably with “one or more.” Additionally, as used herein, the article “the” is intended to include one or more items associated with the article “the” and may be used interchangeably with “the one or more.” Furthermore, as used herein, the term “set” is intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, etc.) and may be used interchangeably with “one or more.” When referring to only one item, the phrase “only one” or similar language is used. Furthermore, as used herein, the terms “having,” “having,” “with,” etc., are intended to be open-ended terms. Furthermore, the phrase “based on” is intended to mean “at least partially based on” unless explicitly stated otherwise. Furthermore, as used herein, the term “or” when used in series is intended to be inclusive and may be used interchangeably with “and / or” unless explicitly stated otherwise (e.g., if used in conjunction with “any” or “only one of them”). Furthermore, for ease of description, spatially relative terms such as “below,” “under,” “above,” “over,” etc., may be used herein to describe the relationship of one element or feature to another element or feature shown in the figures. In addition to the orientations described in the figures, spatially related terms are intended to include different orientations of equipment, apparatus, and / or elements in use or operation. The equipment may be oriented in other ways (rotated 90 degrees or in other directions), and the spatially relative descriptions used herein may be interpreted accordingly.

[0067] 100: Optical devices 102: Transmitter Array 104: Launcher / Launcher Group / First Launcher Group / Second Launcher Group 106: Integrated Optical Components 108: Lens segment 110: Beam 112a: First contact part 112b: Second contact part

Claims

1. A bottom-emitting vertical-cavity surface-emitting laser chip, comprising: A vertical-cavity surface-emitting (VCSEL) laser array includes multiple VCSELs, wherein a first group of VCSELs is connected to a first contact portion of a bottom-emitting VCSEL wafer, and a second group of VCSELs is connected to a second contact portion of the bottom-emitting VCSEL wafer, wherein the first and second contacts are located on different sides of the bottom-emitting VCSEL wafer; and an integrated optical element including multiple lens segments, wherein the integrated optical element is configured to guide a beam provided by the multiple VCSELs to a specific angular range to create a diffusion pattern using the beam provided by the multiple VCSELs, wherein the surface of the first lens segment is inclined to guide the beam from the first VCSELs at a first angle toward a first edge of the diffusion pattern, wherein a second lens segment of the multiple lens segments is adjacent to the first lens segment. The surface of the second lens segment is inclined so that the beam of the second vertical cavity surface-emitting laser from the plurality of vertical cavity surface-emitting lasers is guided at a second angle toward the second edge of the diffusion pattern. The third lens segment of the plurality of lens segments is adjacent to the second lens segment, and the surface of the third lens segment is inclined so that the beam of the third vertical cavity surface-emitting laser from the plurality of vertical cavity surface-emitting lasers is guided at a third angle toward the first edge of the diffusion pattern.

2. The bottom-emitting vertical-cavity surface-emitting laser wafer as claimed in claim 1, wherein the plurality of lens segments are recessed from the top surface of the integrated optical element by a spaced distance.

3. The bottom-emitting vertical-cavity surface-emitting laser wafer as claimed in claim 1, wherein the first contact portion and the second contact portion are on the same side of the bottom-emitting vertical-cavity surface-emitting laser wafer.

4. The bottom-emitting vertical-cavity surface-emitting laser wafer as claimed in claim 1, wherein the first group of vertical-cavity surface-emitting lasers includes the first vertical-cavity surface-emitting laser and the third vertical-cavity surface-emitting laser, and wherein the second group of vertical-cavity surface-emitting lasers includes the second vertical-cavity surface-emitting laser.

5. The bottom-emitting vertical-cavity surface-emitting laser wafer as claimed in claim 1, wherein light from one of the plurality of vertical-cavity surface-emitting lasers is present in a portion of the diffusion pattern, the portion being smaller than the whole of the diffusion pattern.

6. The bottom-emitting vertical-cavity surface-emitting laser wafer as claimed in claim 1, wherein the transition between the first lens segment and the second lens segment is smooth.

7. The bottom-emitting vertical-cavity surface-emitting laser wafer as claimed in claim 1, wherein the vertical-cavity surface-emitting lasers of the plurality of vertical-cavity surface-emitting lasers are connected such that the guide angle provided by the plurality of lens segments varies sequentially along a specific direction across the vertical-cavity surface-emitting laser array.

8. The bottom-emitting vertical-cavity surface-emitting laser wafer as claimed in claim 7, wherein the guide angle provided by the plurality of lens segments alternates between negative and positive angles in a specific direction across the vertical-cavity surface-emitting laser array.

9. An optical device comprising: A vertical cavity surface-emitting laser array includes multiple vertical cavity surface-emitting lasers, wherein a first group of the multiple vertical cavity surface-emitting lasers is connected to a first contact portion of the optical device, and a second group of the multiple vertical cavity surface-emitting lasers is connected to a second contact portion of the optical device, wherein the first contact portion and the second contact portion are on different sides of the optical device. The system also includes an integrated optical element comprising multiple lens segments for guiding beams provided by the plurality of vertical-cavity surface-emitting lasers (VCSELs) to a specific angular range to create a diffusion pattern using the beams provided by the plurality of VCSELs. Each lens segment is configured to guide a beam from one of the plurality of VCSELs at a specific angle in association with the created diffusion pattern. A second lens segment of the plurality of lens segments is adjacent to a first lens segment, a third lens segment of the plurality of lens segments is adjacent to the second lens segment, and a fourth lens segment of the plurality of lens segments is adjacent to the third lens segment. The surfaces of the first and second lens segments are inclined to guide beams from two individual VCSELs at angles opposite to the surfaces of the VCSEL array, such that one of the beams corresponding to the first lens segment extends toward a first edge of the diffusion pattern, and the other of the beams corresponding to the second lens segment extends toward a second edge of the diffusion pattern. The surfaces of the third and fourth lens segments are inclined to guide beams from two individual vertical cavity surface-emitting lasers at an angle having substantially the same direction relative to the surface of the vertical cavity surface-emitting laser array, such that the beams associated with the third and fourth lens segments extend toward the first edge of the diffusion pattern.

10. The optical device as claimed in claim 9, wherein the plurality of lens segments are recessed from the top surface of the integrated optical element by a spaced distance.

11. The optical device as claimed in claim 9, wherein the first contact portion and the second contact portion are on the same side of the optical device.

12. The optical device as claimed in claim 9, wherein the size of the coverage area of ​​the integrated optical element matches or is smaller than the size of the coverage area of ​​the optical device.

13. The optical device of claim 9, wherein light from one of the plurality of vertical cavity surface-emitting lasers is present in a portion of the diffusion pattern, the portion being smaller than the whole of the diffusion pattern.

14. The optical device as claimed in claim 9, wherein the transition between the first lens segment and the second lens segment is smooth.

15. An optical device comprising: A vertical-cavity surface-emitting laser (VCSEL) array includes multiple VCSELs, wherein a first group of VCSELs is connected to a first contact portion of the optical device, and a second group of VCSELs is connected to a second contact portion of the optical device; wherein the first and second contacts are located on different sides of the optical device; and an integrated optical element including multiple lens segments, wherein the integrated optical element is configured to guide a beam provided by the multiple VCSELs to a specific angular range to create a diffusion pattern using the beam provided by the multiple VCSELs, wherein the surface of the first lens segment is inclined to guide the beam from the first VCSELs at a first angle toward a first edge of the diffusion pattern, wherein a second lens segment of the multiple lens segments is adjacent to the first lens segment, and wherein the surface of the second lens segment is inclined to guide the beam from the second VCSELs at a second angle toward a second edge of the diffusion pattern. The third lens segment of the plurality of lens segments is adjacent to the second lens segment, and the surface of the third lens segment is inclined so that the beam of the third vertical cavity surface-emitting laser from the plurality of vertical cavity surface-emitting lasers is guided at a third angle toward the first edge of the diffusion pattern.

16. The optical device of claim 15, wherein the integrated optical element has a first side edge, a second side edge and a front edge extending between the first side edge and the second side edge, wherein the plurality of lens segments are arranged along the front edge, and wherein the first lens segment is adjacent to the first side edge of the integrated optical element.

17. The optical device of claim 15, wherein the first group of vertical cavity surface-emitting lasers includes the first vertical cavity surface-emitting laser and the third vertical cavity surface-emitting laser, and wherein the second group of vertical cavity surface-emitting lasers includes the second vertical cavity surface-emitting laser.

18. The optical device of claim 15, wherein the plurality of lens segments are recessed from the top surface of the integrated optical element at a distance from the periphery of the emission region.

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