Emitter array with multiple groups of interspersed emitters

An optical device may include an emitter array including a plurality of emitter groups. Each emitter group may be independently addressable from other emitter groups, of the plurality of emitter groups, for independently lasing. Emitters of the plurality of emitter groups may be interspersed within the emitter array such that a minimum emitter-to-emitter distance within the emitter array is less than a minimum emitter-to-emitter distance within any of the emitter groups.

TECHNICAL FIELD

The present disclosure relates to an emitter array and, more particularly, to an emitter array with multiple groups of interspersed emitters.

BACKGROUND

An emitter can include a vertical-emitting device, such as a vertical cavity surface emitting laser (VCSEL). A VCSEL is a laser in which a beam is emitted in a direction perpendicular to a surface of the VCSEL (e.g., vertically from a surface of the VCSEL). Multiple emitters may be arranged in an emitter array with a common substrate.

SUMMARY

According to some implementations, an optical device may include an emitter array including a plurality of emitter groups, each emitter group being independently addressable from other emitter groups, of the plurality of emitter groups, for independently lasing, and emitters of the plurality of emitter groups being interspersed within the emitter array such that a minimum emitter-to-emitter distance within the emitter array is less than a minimum emitter-to-emitter distance within any of the emitter groups.

According to some implementations, an optical device may include an emitter array including a first plurality of emitters, a second plurality of emitters, and a third plurality of emitters, wherein emitters from the first plurality of emitters the second plurality of emitters, and the third plurality of emitters are interspersed in the emitter array, wherein a first minimum emitter-to-emitter distance between any two adjacent emitters of the emitter array is less than a second minimum emitter-to-emitter distance, the second minimum emitter-to-emitter distance being a minimum emitter-to-emitter distance between any two emitters of the first plurality of emitters, or a minimum emitter-to-emitter distance between any two emitters of the second plurality of emitters, or a minimum emitter-to-emitter distance between any two emitters of the third plurality of emitters, wherein the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters are independently addressable for independent lasing.

According to some possible implementations, a vertical cavity surface emitting laser (VCSEL) array may include at least three groups of VCSELs, wherein VCSELs of a first group of the at least three groups of VCSELs are interspersed among VCSELs of a second group of the at least three groups of VCSELs, the VCSELs of the second group of VCSELs are interspersed among VCSELs of a third group of the at least three groups of VCSELs, and the VCSELs of the third group of the at least three groups of VCSELs are interspersed among the VCSELs of the first group of the at least three groups of VCSELs, wherein a first minimum emitter-to-emitter distance between any two adjacent VCSELs of the at least three groups of VCSELs of the VCSEL array is less than a second minimum emitter-to-emitter distance between two VCSELs of any one of the at least three groups of VCSELs, wherein the VCSEL array is configured such that the at least three groups of VCSELs are capable of lasing independently of each other.

According to some possible implementations, a method may include providing a substrate on which a laser array is to be formed; forming, after providing the substrate, first lasers of the laser array, second lasers of the laser array, and third lasers of the laser array on or within the substrate such that: the first lasers are interspersed among the second lasers, the second lasers are interspersed among the third lasers, and the third lasers are interspersed among the first lasers, a first minimum emitter-to-emitter distance between any two adjacent lasers of the laser array is less than a corresponding second minimum emitter-to-emitter distance between two of the first lasers, two of the second lasers, or two of the third lasers, and the first lasers, the second lasers, and the third lasers are electrically isolated from each other for independent lasing; and electrically connecting the first lasers, the second lasers, and the third lasers to corresponding electrodes.

DETAILED DESCRIPTION

When emitter arrays are used for structured-light three-dimensional (3D) sensing, a manufacturer may want to pack more emitters onto a single die. However, for some 3D sensing systems it is necessary to distinguish individual emitters projected into a scene. The light from the emitters may be projected through lenses and or other optics and come into focus again at an image plane. At the image plane, the emitters will appear separated in proportion to their displacement on the die. However, at depths closer or further from the image plane (e.g., a z-direction), the projected size of the emitters will increase and eventually they will merge into each other.FIG. 6is a diagram illustrating these principles of depth-of-field of an emitter array. For the system to function over a wide variation in depth, the beam divergence needs to be sufficiently small and there needs to be sufficient separation between emitters so there is a sufficient depth-of-field from the image plane where it is possible to distinguish individual emitters. As emitters are more closely spaced, emission areas of the emitters must be reduced correspondingly to avoid overlap of the emission areas too near to the image plane even though the emission areas may not overlap on the chip itself. Furthermore, with a smaller emission area, variation in a diameter or a size (e.g., an optical aperture) of the emitters needs to be reduced in order to maintain a fixed percentage error (e.g., less than +/−20 percent) in current density and output power of individual emitters (which are typically driven in parallel from a single contact). Reducing a diameter and/or size of emitters of an emitter array results in reduced process yield. This tradeoff between emitter size and yield normally limits the emitter spacing on the chip. This invention provides a chip design to overcome this limitation.

Some implementations described herein provide an emitter array with multiple groups of interspersed emitters (e.g., chosen to permit larger emitter sizes with a smaller fabrication spacing and/or a wider range of depth of sensing than otherwise possible with a single group of emitters used in a 3D sensing system). For example, some implementations described herein provide an emitter array with interspersed groups of emitters arranged so that a minimum emitter-to-emitter (e.g., center-to-center distance or spacing) between proximate emitters within each group is substantially larger than a minimum emitter-to-emitter distance between adjacent emitters of the emitter array.

Specifically, some implementations described herein provide for larger emitters with larger variation in aperture sized in high density configurations and/or provide for sensing over a longer depth of field, as compared to emitters used in conventional high density emitter arrays for structured light. For example, a conventional emitter array with a minimum emitter-to-emitter distance of 24 microns (μm) may need emitter apertures with a diameter of 7 μm in order to avoid overlap of projected spots of adjacent emitters near (e.g., 5 centimeters (cm) away from) an image plane. To ensure that optical power and operating current density do not vary more than, for example, +/−20 percent, the emitter size variation may need to be less than +/−10 percent or +/−0.7 μm. Such a small permissible emitter size variation may decrease yield.

Some implementations described herein, and with respect to the example described above, may facilitate use of emitters patterned with a minimum distance of 24 μm, but with a size greater than 7 μm (for example, 12 μm), and a tolerance on the aperture size of +/−1.2 μm (approximately +/−10 percent of the example emitter size) to ensure that the current density and optical power variation is less than +/−20 percent, and so that emission spots from adjacent emitters do not appreciably overlap within a given distance from an image plane. Such a larger permissible emitter size variation may increase yield. Additionally, or alternatively, some implementations described herein provide for use of an emitter array with the same minimum distance between emitters (e.g., but having an intermediate size of, for example, 10 μm) while extending the depth of field beyond, for example, 5 cm from the image plane (e.g., to 8 cm) with respect to overlap of emission spots for adjacent emitters.

FIGS. 1A and 1Bare diagrams depicting a top-view of an example emitter100and a cross-sectional view150of example emitter100along the line X-X, respectively. As shown inFIG. 1A, emitter100may include a set of emitter layers constructed in an emitter architecture. In some implementations, emitter100may correspond to one or more vertical-emitting devices described herein.

As shown inFIG. 1A, emitter100may include an implant protection layer102that is circular in shape, in this example. In some implementations, implant protection layer102may have another shape, such as an elliptical shape, a polygonal shape, or the like. Implant protection layer102is defined based on a space between sections of implant material (not shown) included in emitter100.

As shown by the medium gray and dark gray areas inFIG. 1A, emitter100includes an ohmic metal layer104(e.g., a P-Ohmic metal layer or an N-Ohmic metal layer) that is constructed in a partial ring-shape (e.g., with an inner radius and an outer radius). The medium gray area shows an area of ohmic metal layer104covered by a protective layer (e.g. a dielectric layer, a passivation layer, and/or the like) of emitter100and the dark gray area shows an area of ohmic metal layer104exposed by via106, described below. As shown, ohmic metal layer104overlaps with implant protection layer102. Such a configuration may be used, for example, in the case of a P-up/top-emitting emitter100. In the case of a bottom-emitting emitter100, the configuration may be adjusted as needed.

Not shown inFIG. 1A, emitter100includes a protective layer in which via106is formed (e.g., etched). The dark gray area shows an area of ohmic metal layer104that is exposed by via106(e.g., the shape of the dark gray area may be a result of the shape of via106) while the medium grey area shows an area of ohmic metal layer104that is covered by the protective layer. The protective layer may cover all of the emitter other than the vias. As shown, via106is formed in a partial ring-shape (e.g., similar to ohmic metal layer104) and is formed over ohmic metal layer104such that metallization on the protection layer contacts ohmic metal layer104. In some implementations, via106and/or ohmic metal layer104may be formed in another shape, such as a full ring-shape or a split ring-shape.

As further shown, emitter100includes an optical aperture108in a portion of emitter100within the inner radius of the partial ring-shape of ohmic metal layer104. Emitter100emits a laser beam via optical aperture108. As further shown, emitter100also includes a current confinement aperture110(e.g., an oxide aperture formed by an oxidation layer of emitter100(not shown)). Current confinement aperture110is formed below optical aperture108.

As further shown inFIG. 1A, emitter100includes a set of trenches112(e.g., oxidation trenches) that are spaced (e.g., equally, unequally) around a circumference of implant protection layer102. How closely trenches112can be positioned relative to the optical aperture108is dependent on the application, and is typically limited by implant protection layer102, ohmic metal layer104, via106, and manufacturing tolerances.

The number and arrangement of layers shown inFIG. 1Aare provided as an example. In practice, emitter100may include additional layers, fewer layers, different layers, or differently arranged layers than those shown inFIG. 1A. For example, while emitter100includes a set of six trenches112, in practice, other configurations are possible, such as a compact emitter that includes five trenches112, seven trenches112, and/or the like. In some implementations, trench112may encircle emitter100to form a mesa structure dt(seeFIG. 1B). As another example, while emitter100is a circular emitter design, in practice, other designs may be used, such as a rectangular emitter, a hexagonal emitter, an elliptical emitter, or the like. Additionally, or alternatively, a set of layers (e.g., one or more layers) of emitter100may perform one or more functions described as being performed by another set of layers of emitter100.

Notably, while the design of emitter100is described as including a VCSEL, other implementations are possible. For example, the design of emitter100may apply in the context of another type of optical device, such as a light emitting diode (LED), or another type of vertical emitting (e.g., top emitting or bottom emitting) optical device. Additionally, the design of emitter100may apply to emitters of any wavelength, power level, emission profile, and/or the like. In other words, emitter100is not particular to an emitter with a given performance characteristic.

The example cross-sectional view shown inFIG. 1Bmay represent a cross-section of emitter100that passes through, or between, a pair of trenches112(e.g., as shown by the line labeled “X-X” inFIG. 1A). As shown, emitter100may include a backside cathode layer128, a substrate layer126, a bottom mirror124, an active region122, an oxidation layer120, a top mirror118, an implant isolation material116, a protective layer114(e.g. a dielectric passivation/mirror layer), and an ohmic metal layer104. As shown, emitter100may have, for example, a total height that is approximately 10 μm.

Backside cathode layer128may include a layer that makes electrical contact with substrate layer126. For example, backside cathode layer128may include an annealed metallization layer, such as an AuGeNi layer, a PdGeAu layer, or the like.

Substrate layer126may include a base substrate layer upon which epitaxial layers are grown. For example, substrate layer126may include a semiconductor layer, such as a GaAs layer, an InP layer, and/or the like.

Bottom mirror124may include a bottom reflector layer of emitter100. For example, bottom mirror124may include a distributed Bragg reflector (DBR). Bottom mirror124is shown as the white area beneath active region122between the left and right portions of isolation material116.

Active region122may include a layer that confines electrons and defines an emission wavelength of emitter100. For example, active region122may be a quantum well.

Oxidation layer120may include an oxide layer that provides optical and electrical confinement of emitter100. In some implementations, oxidation layer120may be formed as a result of wet oxidation of an epitaxial layer. For example, oxidation layer120may be an Al2O3layer formed as a result of oxidation of an AlAs or AlGaAs layer. Trenches112may include openings that allow oxygen (e.g., dry oxygen, wet oxygen) to access the epitaxial layer from which oxidation layer120is formed.

Current confinement aperture110may include an optically active aperture defined by oxidation layer120. A size of current confinement aperture110may range, for example, from approximately 4 μm to approximately 20 μm. In some implementations, a size of current confinement aperture110may depend on a distance between trenches112that surround emitter100. For example, trenches112may be etched to expose the epitaxial layer from which oxidation layer120is formed. Here, before protective layer114is formed (e.g., deposited), oxidation of the epitaxial layer may occur for a particular distance (e.g., identified as doinFIG. 1B) toward a center of emitter100, thereby forming oxidation layer120and current confinement aperture110. In some implementations, current confinement aperture110may include an oxide aperture. Additionally, or alternatively, current confinement aperture110may include an aperture associated with another type of current confinement technique, such as an etched mesa, a region without ion implantation, a lithographically defined intra-cavity mesa and regrowth, or the like.

Top mirror118may include a top reflector layer of emitter100. For example, top mirror118may include a DBR. Top mirror118is shown as the white area above oxidation layer120between the left and right portions of isolation material116.

Implant isolation material116may include a material that provides electrical isolation. For example, implant isolation material116may include an ion implanted material, such as a hydrogen/proton implanted material or a similar implanted element to reduce conductivity. In some implementations, implant isolation material116may define implant protection layer102.

Protective layer114may include a layer that acts as a protective passivation layer and which may act as an additional DBR. For example, protective layer114may include one or more sub-layers (e.g., a dielectric passivation layer and/or a mirror layer, a SiO2layer, a Si3N4layer, an Al2O3layer, or other layers) deposited (e.g., by chemical vapor deposition, atomic layer deposition, or other techniques) on one or more other layers of emitter100.

As shown, protective layer114may include one or more vias106that provide electrical access to ohmic metal layer104. For example, via106may be formed as an etched portion of protective layer114or a lifted-off section of protective layer114. Optical aperture108may include a portion of protective layer114over current confinement aperture110through which light may be emitted.

Ohmic metal layer104may include a layer that makes electrical contact through which electrical current may flow. For example, ohmic metal layer104may include a Ti and Au layer, a Ti and Pt layer and/or an Au layer, or the like, through which electrical current may flow (e.g., through a bondpad (not shown) that contacts ohmic metal layer104through via106). Ohmic metal layer104may be P-ohmic, N-ohmic, and/or the like. Selection of a particular type of ohmic metal layer104may depend on the architecture of the emitters. Ohmic metal layer104may provide ohmic contact between a metal and a semiconductor and/or may provide a non-rectifying electrical junction and/or may provide a low-resistance contact.

In some implementations, emitter100may be manufactured using a series of steps. For example, bottom mirror124, active region122, oxidation layer120, and top mirror118may be epitaxially grown on substrate layer126, after which ohmic metal layer104may be deposited on top mirror118. Next, trenches112may be etched to expose oxidation layer120for oxidation. Implant isolation material116may be created via ion implantation, after which protective layer114may be deposited. Via106may be etched in protective layer114(e.g., to expose ohmic metal layer104for contact). Plating, seeding, and etching may be performed, after which substrate layer126may be thinned and/or lapped to a target thickness. Finally, backside cathode layer128may be deposited on a bottom side of substrate layer126.

The number, arrangement, thicknesses, order, symmetry, or the like, of layers shown inFIG. 1Bis provided as an example. In practice, emitter100may include additional layers, fewer layers, different layers, differently constructed layers, or differently arranged layers than those shown inFIG. 1B. Additionally, or alternatively, a set of layers (e.g., one or more layers) of emitter100may perform one or more functions described as being performed by another set of layers of emitter100and any layer may comprise more than one layer.

FIGS. 2A-2Dare diagrams depicting one or more example implementations200described herein.FIG. 2Ashows a die202(e.g., a chip, a portion of a wafer, and/or the like) on which an emitter array has been formed. For example, and as described below, the emitter array may be an emitter array with multiple groups of interspersed emitters. Notably, while some example implementations described herein are described in the context of an emitter array that emits light through an epitaxial side of the chip (top-emitting), the techniques and apparatuses described herein are applicable to emitter arrays that emit light which travels through the substrate and out the opposite side of the die (bottom-emitting).

As shown inFIG. 2A, the emitter array includes various emitters204(shown as black, white, and striped circles). For example, an emitter204may include a laser, a vertical-cavity surface-emitting laser (VCSEL), a vertical external-cavity surface-emitting laser (VECSEL), a light-emitting diode (LED), an optical device, and/or the like. Emitters204may each be included in one of multiple groups205of emitters204. For example, the emitters204shown by black circles may be a first group205-1of emitters204, the emitters204shown by white circles may be a second group205-2of emitters204, and the emitters204shown by striped circles may be a third group205-3of emitters204. The various groups205of emitters204are described in more detail below.

As shown inFIG. 2A, die202may include multiple electrodes206(e.g., shown as electrodes206-1through206-3) to provide electrical power to emitters204of the emitter array on die202. Additional electrodes may be located on the opposite side of the die202. Each electrode206may be an anode or a cathode. Electrodes206may provide electrical connection, respectively, to different groups205-X (where X is the index of a group of emitters204) of emitters204of the emitter array. For example, electrode206-1may provide electrical connection to a first group205-1of emitters204, electrode206-2may provide electrical connection to a second group205-2of emitters204, and electrode206-3may provide electrical connection to a third group205-3of emitters204. An electrode206may also provide electrical connection to more than one group205of emitters204(e.g., as a common cathode or a shared electrode). An electrode206may provide electrical power (or current) to a specific group205-X of emitters204and not to other groups205-Y,205-Z of emitters204(where Y and Z denote the index of groups other than X). For example, electrode206-1may provide electrical power to the first group205-1of emitters204and may not provide electrical power to other groups205-1,205-2of emitters204.

Different groups205of emitters204may be independently addressable for independent lasing during operation. For example, a first group205-1of emitters204may be independently addressable for lasing independently from other groups205-2,205-3of emitters204formed on die202(e.g., the first group205-1of emitters204may be powered and/or may lase independently from the second group205-2of emitters204and the third group205-3of emitters204, and/or the like). Independent addressability may be based on separate electrical connections respectively between individual electrodes206-1,206-2,206-3and specific groups205-1,205-2,205-3of emitters204, as described in more detail elsewhere herein.

As shown by reference number208, emitters from different groups of emitters204may be interspersed among each other. For example, an emitter204from a205-1group of emitters204may be adjacent to one or more emitters from one or more other groups205-2,205-3of emitters204. Continuing with the previous example, and referring to the specific emitters204shown by reference number208, an emitter204from the first group205-1of emitters204(shown as the black circle with respect to reference number208) is adjacent to two emitters204from the second group205-2of emitters204(shown as the two white circles adjacent to the black circle, one of which is shown in connection with reference number208) and an emitter204from the third group205-3of emitters204(shown as a striped circle adjacent to the black circle, also shown in connection with reference number208).

A first minimum emitter-to-emitter distance (also referred to herein as a “global minimum emitter-to-emitter distance”) between two adjacent emitters204of the emitter array205may be less than a corresponding second minimum emitter-to-emitter distance (also referred to herein as a “minimum intra-group emitter-to-emitter distance”) between two emitters204of the first group205-1of emitters204, two emitters204of the second group205-2of emitters204, or two emitters204of the third group205-3of emitters204. For example, a first minimum emitter-to-emitter distance between the black emitter204(from the first group205-1of emitters204) shown with respect to reference number208and a white emitter204(from the second group205-2of emitters204) or a striped emitter204(from the third group205-3of emitters204) may be less than a second minimum emitter-to-emitter distance between two proximate black emitters204of the group205-1of emitter array. In other words, a first a global minimum emitter-to-emitter distance of the set of emitters205between two adjacent emitters204which may be of different205-X,205-Y groups of emitters204may be less than a second minimum emitter-to-emitter distance between two proximate emitters204of the same205-X group of emitters204. As will be described below, two emitters204from a same group205-X of emitters204may be proximate in the context of the same group of emitters204(e.g., a first emitter204is proximate to a second emitter204in the context of a group205-X of emitters204if the first emitter204and the second emitter204are in the same205-X group of emitters204, and the first emitter204is the nearest neighbor in that group to the second emitter204, or vice versa, even though one or more other emitters204included in one or more other groups205-Y,205-Z of emitters204are between the first emitter204and the second emitter204). Y and Z denote the index of groups other than X.

A product of the global minimum emitter-to-emitter distance and a value equal to at least a square root of 2 may be less than the minimum intra-group emitter-to-emitter-distance for a group of emitters204. In other words, the minimum intra-group emitter-to-emitter-distance may be greater than a square root of two times the global minimum emitter-to-emitter distance. In this way, emitters204in the set of all groups205of emitters204may be spaced closer to each other than two emitters204of a same group205-X of emitters204. Additionally, or alternatively, the difference in intra-group (e.g., within a group) and global minimum emitter-to-emitter distances facilitates increased emitter size for a given area of die202(e.g., larger aperture diameter) relative to conventional emitter arrays, thereby facilitating wider manufacturing tolerances for dies202, and consequently lower chip costs through a higher yield rate.

In operation, an emission pattern of emitters204of the emitter array is projected (and possibly repeated in multiple patterns) through optics into a scene. The scene may contain various surfaces and projecting the patterns of dots is done to measure the 3D profile of these surfaces. The emission pattern of spots comes into focus on an image plane somewhere in the scene. Not all surfaces of interest will be located precisely at the image plane, but may be near the image plane. At the image plane, spots (i.e., images of the emitters204) are their smallest and, at comparatively further distances from the image plane, will be comparatively larger in size (and also closer together). This variation in size and spacing permits assessment of depth of various surfaces in the scene. However, at some distance from the image plane, the spots of the emission pattern will begin to merge into one another and individual dots will no longer be discernable and sensing of depth will not be possible. Thus, there is a range along an axis perpendicular to the image plane over which sensing depth is possible. This range is referred to herein as a sensor depth-of-field. A sch

The minimum emitter-to-emitter distance for a particular group,205-X, of emitters204may be selected to avoid overlap of emission spots at a particular depth of field (distance from the image plane) when light from the emitters204of that group205-X are projected into a scene. For example, by maintaining a minimum emitter-to-emitter spacing between the closest emitters204from a particular group205-X of emitters204, the configuration of205-X emitters204described herein may avoid overlap between the proximate emitters204at a particular distance from the image plane (or depth-of-field) when only group205-X is used to illuminate a scene at a particular time. An emitter-to-emitter distance may refer to one or more of various manners of evaluating a distance (or spacing) between emitters204. For example, an emitter-to-emitter distance may be center-to-center spacing, a distance between optical apertures of two emitters204(e.g., a center-to-center distance), a distance between oxide trenches of two emitters204(e.g., a trench-to-trench distance), and/or the like.

InFIG. 2A, the emitter array has a random pattern of emitters204formed from the first group205-1of emitters204, the second group205-2of emitters204, and the third group205-3of emitters204. As a result, the emitter array may emit a random pattern of spots when all three groups of emitters204are lasing at the same time. Specific patterns of the different groups of emitters204of the emitter array are described below in connection withFIGS. 2B-2D, and other patterns of emitters204of an emitter array are shown in and described below with respect toFIGS. 3 and 4.

FIG. 2Bshows the first group205-1of emitters204of the emitter array of die202shown inFIG. 2Awithout showing the second group205-2of emitters204(white circles fromFIG. 2A) or the third group205-3of emitters204(striped circles fromFIG. 2A). As shown inFIG. 2B, emitters204of the first group205-1of emitters204are arranged in a random pattern of emitters204. A random pattern of emitters204is a pattern of emitters204without a particular or discernable organization or order (i.e., that is not able to be predicted) Reference number210shows two adjacent emitters204of the first group205-1of emitters204that are separated by a second minimum emitter-to-emitter distance (e.g., a minimum intra-group emitter-to-emitter distance) of the first group205-1of emitters204. As described elsewhere herein, this second minimum emitter-to-emitter distance may be greater than a first minimum emitter-to-emitter distance between adjacent emitters204of different groups205of emitters204of the emitter array (e.g., any emitters204in the emitter array). As a result, when light from only the first group205-1of emitters204is projected into a scene, the distance from the image plane where the emitters overlap (referred to here as the depth-of-field) may be greater than the depth-of-field when light from all emitters204is projected into a scene.

FIG. 2Cshows the second group of emitters204of the emitter array of die202shown inFIG. 2Awithout showing the first group of emitters204(black circles fromFIG. 2A) or the third group of emitters204(striped circles fromFIG. 2A). As shown inFIG. 2C, emitters204of the second group of emitters204are arranged in a random pattern of emitters204. Reference number212shows an example corresponding second minimum emitter-to-emitter distance between two adjacent emitters204of the second group of emitters204. As described elsewhere herein, this corresponding second minimum emitter-to-emitter distance may be greater than a first minimum emitter-to-emitter distance between adjacent emitters204of different groups of emitters204of the emitter array. As a result, when lasing, the second group of emitters204may have a depth of field that is greater than an array that had emitters sized to avoid overlap when all emitters are lasing.

FIG. 2Dshows the third group of emitters204of the emitter array of die202shown inFIG. 2Awithout showing the first group of emitters204(black circles fromFIG. 2A) or the second group of emitters204(white circles fromFIG. 2A). As shown inFIG. 2D, emitters204of the third group of emitters204are arranged in a random pattern of emitters204. Reference number214shows an example corresponding second minimum emitter-to-emitter distance between two adjacent emitters204of the third group of emitters204. As described elsewhere herein, this corresponding second minimum emitter-to-emitter distance may be greater than a first minimum emitter-to-emitter distance between adjacent emitters204of different groups of emitters204of the emitter array. As a result, when lasing, the third group of emitters204may have a depth of field that is greater than the depth of field when all emitters are lasing.

As described with regard toFIGS. 2B-2D, the first group of emitters204, the second group of emitters204, and the third group of emitters204may be each arranged in a random pattern of emitters. In addition, as described in connection withFIG. 2A, the emitter array overall may have a random pattern of emitters204. In this way, the emitter array may have a random pattern of emitters formed from random patterns of emitters corresponding to the first group of emitters204, the second group of emitters204, and the third group of emitters204. In addition, as shown inFIGS. 2B-2D, the different groups of emitters204that comprise the emitter array may have different random patterns of emitters204. This reduces or eliminates sensing issues that would otherwise occur from the different groups of emitters204having a same pattern of emitters204if the groups were lasing at the same time.

In this way, some implementations described herein provide a die202that includes multiple groups of emitters204and electrodes206to provide electrical connections to to the multiple groups of emitters204. For example, the electrodes206may be configured to independently electrically power the corresponding groups of emitters204. In addition, a first minimum emitter-to-emitter distance between two adjacent emitters (e.g., adjacent emitters204that are included in different groups of emitters204) of an emitter array formed from the multiple groups of emitters204may be less than a second minimum emitter-to-emitter distance between two emitters of a group of emitters204. For example, a product of the first minimum emitter-to-emitter distance and a square root of two may be less than the second minimum emitter-to-emitter distance. This configuration of die202facilitates closer packing of larger emitters204on die202while reducing or eliminating overlap of emission spots at a depth of field relative to conventional emitter arrays. For example, the first minimum emitter-to-emitter distance may facilitate closer packing of emitters204. In addition, independent and separate lasing of different groups of emitters204in combination with the corresponding second minimum emitter-to-emitter distance may reduce or eliminate overlap of emission spots at a depth of field. Reducing or eliminating overlap of emission spots at a depth of field may increase a depth of field of an emitter array (e.g., by increasing an image depth at which emission spots of the emitter array begin to overlap) relative to conventional emitter arrays. In addition, reducing or eliminating overlap of emission spots at a depth of field may improve optical resolution at the depth of field.

As indicated above,FIGS. 2A-2Dare provided merely as one or more examples. Other examples may differ from what is described with regard toFIGS. 2A-2D. For example, although three different groups of emitters204were shown in, and described with respect to,FIGS. 2A-2D, other example implementations may have different quantities of groups of emitters204.

FIG. 3is a diagram depicting an example implementation300described herein.FIG. 3shows an example configuration of an emitter array on a die202, similar to that described elsewhere herein. For example, the emitter array may include multiple groups of emitters204interspersed with each other and electrodes206to provide electrical connections to the multiple groups of emitters204, similar to that described elsewhere herein. The irregular pattern of emitters204within each group may be helpful to locate the pattern when multiple copies of a particular group of emitters204is projected into a scene. Typically, 3D sensing with structured-light cannot use uniform patterns of spots.

As shown by reference number310, the emitter array may include, for example, three groups of emitters204. For example, the three groups of emitters204may include a first group of emitters204shown by the black circles, a second group of emitters204shown by the white circles, and a third group of emitters204shown by the striped/shaded circles. As further shown inFIG. 3, the multiple groups of emitters204may be arranged in corresponding non-random patterns. A non-random pattern of emitters204is a pattern of emitters with a particular organization or order. For example, a non-random pattern may include a grid pattern, a hexagonal pattern, a known curve pattern, a parabolic pattern, and/or another type of organized or ordered pattern formed from emitters204. For example, and with respect to the first group of (black) emitters204, emitters204of the first group of emitters204may be arranged in a two-dimensional pattern of columns (shown by reference number320) and rows (shown by reference number330).

As further shown inFIG. 3, in some implementations, the first group of emitters204may have irregular spacing between emitters204of the first group of emitters204. That is, emitter-to-emitter distances between pairs emitters204in the first group of emitters204may differ among pairs of emitters204in the first group of emitters204. For example, a spacing between a first emitter204, included in the first group of emitters204. and a second emitter204, included in the first group of emitters204, that is proximate to the first emitter204may be different than a spacing between the first emitter204and a third emitter204, included in the first group of emitters204, that is proximate to the first emitter204. The second group of emitters204and the third group of emitters204may be arranged in a manner similar to that described with regard to the first group of emitters204. In some implementations, a group of emitters204may have regular spacing between emitters204of the group of emitters204. That is, emitter-to-emitter distances between pairs emitters204in the first group of emitters204may be the same among pairs of emitters204in the group of emitters204.

As shown by reference number340, the emitter array on die202may have a non-random pattern of emitters204formed from the multiple groups of emitters204. For example, the emitter array may have a non-random two-dimensional pattern of emitters204, where emitters204of the emitter array are formed in rows and columns of emitters204. In addition, similar to the multiple groups of emitters204, emitters204of the emitter array may have an irregular spacing between emitters204of the emitter array.

As indicated above,FIG. 3is provided merely as one or more examples. Other examples may differ from what is described with regard toFIG. 3.

FIG. 4is a diagram depicting an example implementation400described herein.FIG. 4shows an example configuration of an emitter array on die202, similar to that described elsewhere herein. For example, the emitter array may include multiple groups of emitters204interspersed with each other and electrodes206corresponding to the multiple groups of emitters204, similar to that described elsewhere herein. In addition,FIG. 4shows a manner in which a uniform, non-random pattern of emitters204for an emitter array can be formed from multiple groups of emitters204that have corresponding non-uniform patterns of emitters204.

Reference number410shows an emitter array that includes two groups of emitters204. The two groups of emitters204are shown by the black circles and the white circles. As shown by reference number420, the emitters204may be in a non-random pattern of alternating emitters204(e.g., on a per-row and a per-column basis).

Reference number430shows an emitter array that includes three groups of emitters204, where the three groups of emitters204have corresponding non-uniform patterns of emitters204. A non-uniform pattern of emitters204is a pattern of emitters204selected from a non-random pattern of emitters204such that the selected emitters have no discernable pattern, as described below. As shown by reference number440, to form the emitter array that has a non-random pattern of emitters204formed from multiple groups of emitters204that have corresponding non-uniform patterns of emitters204, a third group of emitters204(shown by the striped circles) may be selected from the first group of emitters204and/or the second group of emitters204described with respect to the emitter array shown by reference number410.

As further shown by reference number440, emitters204selected for the third group of emitters204may form a non-uniform pattern of emitters204. For example, the selected emitters204may not form a random pattern based on having been selected from the non-random pattern of emitters204, and may have no discernable pattern (e.g., such that selected emitters204do not form rows and columns that include similar quantities of emitters204, do not form a pattern that has a particular shape, and/or the like)). As such, the first group of emitters204and the second group of emitters204may additionally have corresponding non-uniform patterns of emitters204after selection of the third group of emitters204. Based on including three non-uniform patterned emitters204, the emitter array shown with respect to reference number420may have sufficient variability in patterns of the emitters204between the different groups of emitters204to reduce or eliminate sensing issues that may occur with the emitter array shown with respect to reference number410due to that emitter array including two groups of emitters204that have similar patterns of emitters204(e.g., a perfectly uniform pattern, when repeated, may be difficult to locate, whereas a non-uniform pattern may be easier to locate). In some cases, including one or more additional groups of emitters204in the emitter array shown with respect to reference number420may further reduce or eliminate sensing issues.

A quantity and/or location of emitters204selected for inclusion in the third group of emitters204may depend on emitter-to-emitter distances of inter-group and intra-group emitters204before and after selection of the emitters204for the third group of emitters204. For example, a threshold quantity of emitters204may need to be selected such that a first minimum emitter-to-emitter distance between two adjacent emitters204of the emitter array is greater than a second minimum emitter-to-emitter distance between two adjacent emitters204of any one of the groups of emitters204, similar to that described elsewhere herein. In the examples shown inFIG. 4, groups of emitters204being chosen from among diagonal emitters204of entire set of emitters204in the emitter array means a minimum emitter-to-emitter distance between emitters204in a given group of emitters is a √2 equal or greater than a minimum emitter-to-emitter distance among emitters in the entire set of emitters204of the emitter array. It is apparent this relation is true when considering the center-to-center to distance between neighboring emitters because the length along the diagonal between neighboring emitter centers is √2 longer than the horizontal or vertical center to center spacing. When considering the distance (gap) between emitters (e.g., which equals the center-to-center spacing less the emitter diameter), the ratio becomes larger than √2 because each distance is smaller by a fixed amount.

As indicated above,FIG. 4is provide merely as an example. Other examples may differ from what is described with regard toFIG. 4.

Notably, while particular examples of intra-group patterns and overall emitter array patterns are shown and described inFIGS. 2A-2D, 3, and 4, other examples are possible. For example, emitters204of an emitter array may form a non-random pattern of emitters204with irregular emitter-to-emitter spacing (e.g., a parabolic grid), a non-random pattern of emitters204with regular emitter-to-emitter spacing, a random pattern with regular emitter-to-emitter spacing, and/or the like. In general, emitters204of a given emitter array may have any combination of pattern and spacing described herein.

FIG. 5is a flow chart of an example process500for forming an emitter array with multiple groups of interspersed emitters204. For example,FIG. 5shows an example process500for manufacturing an emitter array on die202as described above.

As shown inFIG. 5, process500may include providing a substrate on which an emitter array is to be formed (block510). For example, process500may include providing a die (e.g., die202) on which an emitter array (e.g., a laser array) is to be formed. The substrate may include a gallium arsenide (GaAs) substrate and/or the like. The substrate may be separated from a wafer (e.g., a GaAs wafer) prior to forming the emitter array on the substrate.

As further shown inFIG. 5, process500may include forming, after providing the substrate, a first plurality of emitters of the emitter array, a second plurality of emitters of the emitter array, and a third plurality of emitters of the emitter array on or within the substrate (block520). For example, process500may include forming a first plurality of emitters (e.g., a first group of emitters204), a second plurality of emitters (e.g., a second group of emitters204), and a third plurality of emitters (e.g., a third group of emitters204) on or within the substrate after providing the substrate. To form a plurality of emitters, various epitaxial layers may be formed on the substrate. The plurality of emitters may be formed in a pattern, such as a two-dimensional pattern (e.g., a grid pattern, a hexagonal pattern, a random pattern, a non-uniform pattern, and/or the like).

In some implementations, the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters may be formed such that emitters of the first plurality of emitters are interspersed among the second plurality of emitters, emitters of the second plurality of emitters are interspersed among the third plurality of emitters, and emitters of the third plurality of emitters are interspersed among the first plurality of emitters. For example, an emitter from the first plurality of emitters may be adjacent to one or more emitters from the second plurality of emitters and the third plurality of emitters, and likewise for the second plurality of emitters and the third plurality of emitters.

In some implementations, the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters may be formed such that a first minimum emitter-to-emitter distance between any two adjacent emitters of the emitter array is less than a corresponding second minimum emitter-to-emitter distance between two of the first plurality of emitters, two of the second plurality of emitters, or two of the third plurality of emitters. For example, a first minimum emitter-to-emitter distance between any two adjacent emitters of the emitter array may be less than a second minimum emitter-to-emitter distance between two emitters for any of the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters. As a specific example, a product of the first minimum emitter-to-emitter distance and a value equal to at least a square root of two may be less than the second minimum emitter-to-emitter distance.

In some implementations, the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters may be formed such that the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters are electrically isolated from each other for independent lasing. For example, a plurality of emitters may be associated with a metallization layer (e.g., a gold metallization layer, a silver metallization layer, a copper metallization layer, and/or the like) that is electrically isolated from other metallization layers corresponding to other pluralities of emitters. In addition, the emitter array may be associated with electrodes (e.g., electrodes206) that provide electrical connections to the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters, and the electrodes may provide electrical power to the corresponding pluralities of emitters independently.

In some implementations, the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters may be formed in corresponding patterns, and the resulting emitter array may have a pattern of emitters formed from the corresponding patterns. For example, the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters may be formed in a random pattern of emitters such that the emitter array has a random pattern of emitters, similar to that described with respect toFIGS. 2A-2D. Additionally, or alternatively, and as another example, the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters may be formed in a non-random pattern of emitters such that the emitter array has a non-random pattern of emitters with an irregular spacing between emitters of the emitter array, similar to that described with respect toFIG. 3. Additionally, or alternatively, and as another example, the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters may be formed in a non-uniform pattern of emitters such that the emitter array has a non-random pattern of emitters, similar to that described with regard toFIG. 4.

As further shown inFIG. 5, process500may include electrically connecting the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters to corresponding electrodes (block530). For example, process500may include electrically connecting the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters to corresponding electrodes after forming the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters. Electrically connecting the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters to the corresponding electrodes may include forming metallization layers corresponding to the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters on the emitter array to electrically connect the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters to the corresponding anodes. For example, the metallization layers may be electrically isolated from each other to facilitate independent powering and/or lasing of different pluralities of emitters.

In some implementations, forming the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters may include forming each of the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters such that the emitter array has a random pattern of emitters.

In some implementations, forming the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters may include forming each of the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters in a non-random pattern such that the emitter array has a non-random pattern of emitters with an irregular spacing between emitters.

In some implementations, forming the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters may include forming each of the first plurality of emitters, second plurality of emitters, and the third plurality of emitters in a non-uniform pattern of emitters such that the emitter array has a non-random pattern of emitters.

In some implementations, forming the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters may include forming the first plurality of emitters, the second plurality of emitters, and the third plurality of emitters such that a product of the first minimum emitter-to-emitter distance and a value equal to at least a square root of two is less than the second minimum emitter-to-emitter distance.

As used herein the term “layer” is intended to be broadly construed as one or more layers and includes layers oriented horizontally, vertically, or at other angles.