Self-mixing interferometry using back-side light-emission type vcsel diode having integrated photodetector

Abstract

To provide an optoelectronic sensing device having a vertical cavity surface emitting laser (VCSEL), a resonant cavity photodetector (RCPD), and a tunnel junction.SOLUTION: VCSEL is at least partially defined by a first set of semiconductor layers disposed on a substrate. The first set of semiconductor layers includes a first active region. The VCSEL is configured to emit laser light toward a substrate upon application of a first bias voltage and experience self-mixing interference upon reception of reflected or backscattered light, and RCPD is at least partially defined by a second set of semiconductor layers that are disposed on the substrate to be vertically adjacent to the VCSEL. The second set of semiconductor layers include a second active region. The RCPD is configured to detect self-mixing interference upon application of a second bias voltage. The tunnel junction is disposed between the first active region and the second active region.SELECTED DRAWING: None

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is non-provisional and claims the benefit under 35 USC § 119(e) of U.S. Provisional Patent Application No. 63 / 540,253, filed September 25, 2023, the contents of which are incorporated by reference herein as if fully disclosed herein.

[0002] The described embodiments relate generally to optical sensing, and more particularly to optical sensing based on self-mixing interferometry (SMI). [Background technology]

[0003] Electronic devices may include photoelectronic sensors. For example, photoelectronic sensors may be included in portable electronic devices such as mobile phones, tablet computers, laptop computers, cameras, portable music players, personal digital assistants, vehicle navigation systems, robot navigation systems, electronic watches, health or fitness tracking devices, and other portable or mobile devices. Photoelectronic sensors may also be included in devices that are semi-permanently located (or installed) in a single location (e.g., security cameras, doorbells, door locks, thermostats, refrigerators, or other appliances). Some of these electronic devices may include one or more input elements or surfaces, such as cameras, buttons, or touch screens, through which a user can input commands or data via touch, pressure, gesture, or image. The touch, pressure, gesture, or image may be detected by a component of the electronic device (e.g., one or more photoelectronic sensors) that detects presence, distance, location, motion, topology, or other parameters. The same and / or other electronic devices may also or alternatively include one or more sensors, which may sense proximity, distance, particle velocity, or other parameters without receiving intentional user input.

[0004] Some optoelectronic sensors may include a light source (e.g., a laser) that emits a beam of light towards or through an input surface. Distance, location, movement, topology, or other parameters of the input surface or objects opposite the input surface can be inferred from reflection or backscattering of the emitted light from the input surface and / or the objects.

[0005] Some optoelectronic sensors may include a vertical cavity surface emitting laser (VCSEL) diode. A VCSEL diode may undergo self-mixing interference, where a reflection of its emitted laser light is received back into its resonant cavity. The self-mixing interference may induce a shift in the properties, e.g., wavelength, of the laser light generated within the resonant cavity to a different state than if there was no received reflection ("free emission"). If the received reflection is from an input surface or object, the shift in properties may be correlated, for example, with the displacement, distance, motion, speed, or velocity of the input surface or object that caused the reflection. Summary of the Invention

[0006] The term embodiment and similar terms, such as implementations, configurations, aspects, examples, and options, are intended to broadly refer to all of the subject matter of this disclosure and the claims that follow. Statements containing these terms should be understood to neither limit the subject matter described herein nor limit the meaning or scope of the claims that follow. The embodiments of the disclosure contained herein are defined by the claims that follow, not this Summary of the Invention. This Summary of the Invention is a high-level summary of various aspects of the disclosure and introduces some of the concepts that are further described in the Detailed Description section below. This Summary is not intended to identify key or essential features of the claimed subject matter. This Summary is also not intended to be used alone to determine the scope of the claimed subject matter. The subject matter should be understood by reference to the entire specification of this disclosure, any or all drawings, and appropriate portions of each claim.

[0007] An embodiment of the present disclosure relates to an optoelectronic sensing device having a vertical cavity surface emitting laser (VCSEL), a resonant cavity photodetector (RCPD), and a tunnel junction. The VCSEL is at least partially defined by a first set of semiconductor layers disposed on a substrate. The first set of semiconductor layers includes a first active region. The VCSEL is configured to emit laser light toward the substrate upon application of a first bias voltage and to experience self-mixing interference upon receiving reflection or backscattering of the emitted laser light from a target object. The RCPD is at least partially defined by a second set of semiconductor layers vertically adjacent to the VCSEL and disposed on the substrate. The second set of semiconductor layers includes a second active region. The RCPD is configured to detect self-mixing interference during emission of laser light by the VCSEL upon application of a second bias voltage. The tunnel junction is disposed between the first active region and the second active region.

[0008] An embodiment of the present disclosure further relates to an optoelectronic sensing device having a substrate, a set of conductor layers, and a lattice structure disposed on the set of stacked semiconductor layers. The substrate has a front surface and a back surface. The set of stacked semiconductor layers is disposed on the front surface and defines a vertical cavity surface emitting laser (VCSEL) and a resonant cavity photodetector (RCPD). The VCSEL has a first active region within its resonant cavity. The VCSEL is configured to emit primary radiation through the back surface towards the substrate upon application of a first bias voltage. The RCPD has a second active region offset from the first active region.

[0009] An embodiment of the present disclosure also relates to an optoelectronic sensing device having a substrate, a set of stacked semiconductor layers, and at least one electrical conductor. The substrate has a front surface and a back surface. The set of stacked semiconductor layers is disposed on the front surface and defines a set of mesas. The set of mesas includes a first set of one or more mesas and a second set of one or more mesas. Each mesa in the first set of one or more mesas includes a vertical cavity surface emitting laser (VCSEL) and a resonant cavity photodetector (RCPD). The VCSEL has a first active region in its resonant cavity. The VCSEL is configured to emit a primary radiation through the back surface towards the substrate upon application of a first bias voltage. The RCPD has a second active region offset from the first active region. The RCPD is configured to detect self-mixing interference of the primary radiation in the laser cavity of the VCSEL upon receiving reflection or backscattering upon application of a second bias voltage. at least one electrical conductor electrically connected to an element of a first mesa in the first set of one or more mesas and routed onto a portion of a second mesa in the second set of one or more mesas.

[0010] The above summary is not intended to represent each embodiment or every aspect of the present disclosure. Rather, the foregoing summary of the invention merely provides some examples of the novel aspects and features described herein. The above features and advantages of the present disclosure, as well as other features and advantages, will be readily apparent from the following detailed description of exemplary embodiments and modes for carrying out the invention, taken in conjunction with the accompanying drawings and the appended claims. Additional aspects of the present disclosure will become apparent to those skilled in the art in view of the detailed description of the various embodiments, which is provided below with reference to the drawings.

[0011] The disclosure will be readily understood from the following detailed description when taken in conjunction with the accompanying drawings, in which like reference numbers designate like structural elements and in which: [Brief description of the drawings]

[0012] [Figure 1]FIG. 1 is a cross-sectional view of a first exemplary structure of a back-emitting vertical-cavity surface-emitting laser (VCSEL) diode integrated with a resonant-cavity photodetector (RCPD), where the RCPD is positioned away from the primary emission of the VCSEL diode, in accordance with some embodiments of the present disclosure.

[0013] [Diagram 2] FIG. 1 is a cross-sectional view of a second exemplary structure of a back-emitting vertical-cavity surface-emitting laser (VCSEL) diode integrated with a resonant-cavity photodetector (RCPD), in accordance with some embodiments of the present disclosure, where the RCPD is positioned along the primary emission of the VCSEL diode.

[0014] [Diagram 3] 2 illustrates a cross-sectional view of an exemplary optoelectronic sensing device having a first exemplary structure of a back-emitting VCSEL diode integrated with an RCPD as shown in FIG. 1 in accordance with some embodiments of the present disclosure.

[0015] [Figure 4] 1 illustrates a cross-sectional view of a grating structure configured to be disposed on a set of stacked semiconductor layers on a substrate forming an exemplary optoelectronic sensing device, according to some aspects of the present disclosure.

[0016] [Figure 5A] 5A-5C show schematic diagrams of operational circuits in the example optoelectronic sensing device of FIG. 4 depending on whether the backside emitting VCSEL diode has a cathode load or an anode drive, according to some embodiments of the present disclosure. [Figure 5B] 5A-5C show schematic diagrams of operational circuits in the example optoelectronic sensing device of FIG. 4 depending on whether the backside emitting VCSEL diode has a cathode load or an anode drive, according to some embodiments of the present disclosure. [Figure 5C] 5A-5C show schematic diagrams of operational circuits in the example optoelectronic sensing device of FIG. 4 depending on whether the backside emitting VCSEL diode has a cathode load or an anode drive, according to some embodiments of the present disclosure. [Figure 5D]5A-5C show schematic diagrams of operational circuits in the example optoelectronic sensing device of FIG. 4 depending on whether the backside emitting VCSEL diode has a cathode load or an anode drive, according to some embodiments of the present disclosure.

[0017] [Figure 6] 5 illustrates a schematic diagram of an operating circuit in the example optoelectronic sensing device of FIG. 4 in which the bias polarity of the RCPD is switched in the time domain, according to some embodiments of the present disclosure.

[0018] [Figure 7] 3 illustrates a cross-sectional view of an exemplary optoelectronic sensing device having a second exemplary structure of a back-emitting VCSEL diode integrated with an RCPD as shown in FIG. 2 in accordance with some embodiments of the present disclosure.

[0019] [Figure 8A] 8A-8C show schematic diagrams of operational circuits in the example optoelectronic sensing device of FIG. 7 depending on whether the backside emitting VCSEL diode has an anode drive or a cathode load, according to some embodiments of the present disclosure. [Figure 8B] 8A-8C show schematic diagrams of operational circuits in the example optoelectronic sensing device of FIG. 7 depending on whether the backside emitting VCSEL diode has an anode drive or a cathode load, according to some embodiments of the present disclosure. [Figure 8C] 8A-8C show schematic diagrams of operational circuits in the example optoelectronic sensing device of FIG. 7 depending on whether the backside emitting VCSEL diode has an anode drive or a cathode load, according to some embodiments of the present disclosure. [Figure 8D] 8A-8C show schematic diagrams of operational circuits in the example optoelectronic sensing device of FIG. 7 depending on whether the backside emitting VCSEL diode has an anode drive or a cathode load, according to some embodiments of the present disclosure.

[0020] [Figure 9A]1A and 1B show a cross-sectional view and a corresponding schematic diagram, respectively, of an operating circuit of a first exemplary optoelectronic sensing device having a resonant cavity extended to the emission side of a back-emitting VCSEL diode having a multi-junction structure in the optoelectronic sensing device, in accordance with some embodiments of the present disclosure. [Figure 9B] 1A and 1B show a cross-sectional view and a corresponding schematic diagram, respectively, of an operating circuit of a first exemplary optoelectronic sensing device having a resonant cavity extended to the emission side of a back-emitting VCSEL diode having a multi-junction structure in the optoelectronic sensing device, in accordance with some embodiments of the present disclosure.

[0021] [Figure 10A] 1A and 1B show a cross-sectional view and a corresponding schematic diagram, respectively, of an operational circuit of a first exemplary optoelectronic sensing device having multiple sets of back-emitting VCSEL diodes integrated with an RCPD and a first arrangement of electrical connections between the multiple sets, in accordance with some embodiments of the present disclosure. [Figure 10B] 1A and 1B show a cross-sectional view and a corresponding schematic diagram, respectively, of an operational circuit of a first exemplary optoelectronic sensing device having multiple sets of back-emitting VCSEL diodes integrated with an RCPD and a first arrangement of electrical connections between the multiple sets, in accordance with some embodiments of the present disclosure.

[0022] [Figure 11A] 10A and 10B show cross-sectional and corresponding schematic diagrams, respectively, of an operational circuit of a second exemplary optoelectronic sensing device having multiple sets of back-emitting VCSEL diodes integrated with an RCPD and having a second arrangement of electrical connections between the multiple sets, in accordance with some embodiments of the present disclosure. [Figure 11B] 10A and 10B show cross-sectional and corresponding schematic diagrams, respectively, of an operational circuit of a second exemplary optoelectronic sensing device having multiple sets of back-emitting VCSEL diodes integrated with an RCPD and having a second arrangement of electrical connections between the multiple sets, in accordance with some embodiments of the present disclosure.

[0023] [Figure 12A]1A and 1B show cross-sectional and corresponding schematic diagrams, respectively, of an operating circuit of a second exemplary optoelectronic sensing device having a resonant cavity extended to the emission side of a back-emitting VCSEL diode having a multi-junction structure in the optoelectronic sensing device, in accordance with some embodiments of the present disclosure. [Figure 12B] 1A and 1B show cross-sectional and corresponding schematic diagrams, respectively, of an operating circuit of a second exemplary optoelectronic sensing device having a resonant cavity extended to the emission side of a back-emitting VCSEL diode having a multi-junction structure in the optoelectronic sensing device, in accordance with some embodiments of the present disclosure.

[0024] [Figure 13A] 1A-12B show perspective and corresponding cross-sectional views of a first exemplary set of optoelectronic sensing devices, such as the set of optoelectronic sensing devices shown and described with reference to FIGS. 9A-9B or 12A-12B, respectively. [Figure 13B] 1A-12B show perspective and corresponding cross-sectional views of a first exemplary set of optoelectronic sensing devices, such as the set of optoelectronic sensing devices shown and described with reference to FIGS. 9A-9B or 12A-12B, respectively.

[0025] [Figure 14] FIG. 13A shows a top view of an exemplary array of optoelectronic sensing devices as shown and described with reference to FIGS. 13A-13B.

[0026] [Figure 15A] 12A-12B show perspective and corresponding cross-sectional views of a second exemplary set of optoelectronic sensing devices, such as the set of optoelectronic sensing devices shown and described with reference to FIGS. 9A-9B or 12A-12B, respectively. [Figure 15B] 12A-12B show perspective and corresponding cross-sectional views of a second exemplary set of optoelectronic sensing devices, such as the set of optoelectronic sensing devices shown and described with reference to FIGS. 9A-9B or 12A-12B, respectively.

[0027] [Figure 16] FIG. 15B shows a top view of an exemplary array of optoelectronic sensing devices as shown and described with reference to FIGS. 15A-15B.

[0028] [Figure 17] FIG. 13 is a top view of a first exemplary layout of an optoelectronic sensing device, such as the optoelectronic sensing device shown and described with reference to FIGS. 9A-9B or 12A-12B.

[0029] [Figure 18] FIG. 13 is a top view of a second exemplary layout of an optoelectronic sensing device, such as the optoelectronic sensing device shown and described with reference to FIGS. 9A-9B or 12A-12B.

[0030] [Figure 19] FIG. 19 is a top view of a first array of the second exemplary layout of the optoelectronic sensing device shown and described with reference to FIG. 18.

[0031] [Figure 20] FIG. 19 is a top view of a second array of the second exemplary layout of the optoelectronic sensing device shown and described with reference to FIG. 18.

[0032] [Figure 21] FIG. 1 illustrates an example electrical block diagram of an electronic device having an optoelectronic sensor in accordance with some aspects of the present disclosure.

[0033] The use of cross-hatching or shading in the accompanying figures is generally provided to clarify boundaries between adjacent elements and also to facilitate visibility of the figures. As such, neither the presence nor absence of cross-hatching or shading is intended to convey or indicate any preference or requirement for specific materials, material properties, element proportions, element dimensions, commonalities of similarly illustrated elements, or any other characteristics, attributes, or properties with respect to any element shown in the accompanying figures.

[0034] While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed. Rather, the present disclosure is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

[0035] Additionally, it will be understood that the proportions and dimensions (whether relative or absolute) of the various features and elements (and collections and groups thereof), as well as the boundaries, separations and relationships presented therebetween, are provided in the accompanying figures merely to facilitate an understanding of the various embodiments described herein, and therefore may not necessarily be presented or drawn to scale, and are not intended to imply any preferences or requirements for the illustrated embodiments to the exclusion of the embodiments described with reference thereto. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Various embodiments are described with reference to the accompanying drawings, in which like reference numerals are used throughout the drawings to designate similar or equivalent elements. The drawings are not necessarily drawn to scale, but are provided merely to illustrate aspects and features of the present disclosure. While numerous specific details, relationships, and methods are described to provide a thorough understanding of certain aspects and features of the present disclosure, those skilled in the art will recognize that these aspects and features may be implemented without one or more of the specific details, with other relationships, or with other methods. In some instances, well-known structures or operations have not been shown in detail for purposes of explanation. The various embodiments disclosed herein are not necessarily limited to a depicted order of operations or events, as some operations may occur in different orders and / or simultaneously with other operations or events. Moreover, not all depicted operations or events are necessarily required to implement certain aspects and features of the present disclosure.

[0037] For purposes of this detailed description, singular includes plural and vice versa, where appropriate, unless otherwise noted. The word "including" means "including without limitation." Additionally, approximation words such as "about," "almost," "substantially," "approximately," and the like, may be used herein to mean "in," "near," "approximately," "within 3-5% of," "within acceptable manufacturing tolerances of," or any logical combination thereof. Similarly, the terms "vertical" or "horizontal" are intended to further include "within 3-5%" in the vertical or horizontal direction, respectively.

[0038] Additionally, directional terms such as "top," "bottom," "upper," "lower," "front," "back," "over," "under," "above," "below," "left," "right," and the like are used with reference to certain orientations of components in certain figures described below. Because components in various embodiments may be oriented in many different orientations, the directional terms are used for illustrative purposes only and are not intended to be limiting in any way. The directional terms are intended to be interpreted broadly and therefore should not be interpreted to exclude components that are oriented in a different manner. These terms are intended to relate to equivalent orientations as depicted in the referenced figures and are understood in context from the referenced object(s) or element(s), such as from positions commonly used for the object(s) or element(s) or as otherwise described herein. Further, it should be noted that the term "signal" refers to a waveform (e.g., electrical, optical, magnetic, mechanical, or electromagnetic) that can travel through a medium, such as DC, AC, sine wave, triangular wave, square wave, vibration, etc.

[0039] Also, as used herein, the phrase "at least one" preceding a series of items, together with the term "and" or "or" separating any of the items, modifies the list as a whole, not each element of the list. The phrase "at least one" does not require the selection of at least one of each listed item, but rather, the phrase allows for the inclusion of at least one of any of the items, and / or at least one of any combination of the items, and / or at least one of each of the items. By way of example, the phrases "at least one of A, B, and C" or "at least one of A, B, or C" refer, respectively, to only A, only B, or only C, any combination of A, B, and C, and / or one or more of each of A, B, and C. Similarly, it can be understood that the order of elements presented for combined or separated lists provided herein should not be construed as limiting the disclosure to only the order provided.

[0040] The embodiments described herein are directed to optoelectronic sensing devices, such as those that may be used for touch or input sensors, proximity or particle sensors, or other types of sensors, and their structures. Such optoelectronic sensing devices may use one or more back-emitting vertical-cavity surface-emitting laser (VCSEL) diodes with an integrated photodiode, such as a resonant cavity photodiode (RCPD), that receives emitted laser light from the VCSEL diode. An electronic device may use such optoelectronic sensing devices as part of a system for detecting the displacement, distance, motion, speed, or velocity of an object (or "target"). Such an object may be a component of the electronic device, such as an input surface or touchpad, or the target may be external to the electronic device. For example, the optoelectronic sensing device may be part of a camera's autofocus system and may be used to detect the distance to or motion of an external object. In the following, for convenience, all such possible measured kinematic parameters of a target will be referred to simply as "distance or motion".

[0041] In a back-emitting VCSEL diode, typically, laser light is emitted from a resonant cavity that includes at least one active region (a pn junction that surrounds the laser cavity) toward and through the substrate on which the back-emitting VCSEL diode is formed. Reflections of the emitted laser light are received back into the resonant cavity and can induce self-mixing interference in which properties of the laser light, such as wavelength, are altered from the value they would have if they did not receive a reflection. The change in properties can then be correlated with the distance or movement of the object causing the reflection.

[0042] One way the altered characteristic may be detected is by a change in one or more electrical characteristics of the backside emitting VCSEL diode itself, such as voltage, current, power, etc. Alternatively, the altered emitted laser light may be received by a photodiode associated with the backside emitting VCSEL diode, the photodiode having an output parameter related to the altered characteristic of the self-mixed emitted laser light of the VCSEL diode.

[0043] In various embodiments described herein, a back-emitting VCSEL diode may be structured to emit primary radiation from an active region, when forward biased, toward an object through an emitting side of an optoelectronic sensing device, as well as toward a photodiode integrated therein. Changes in the properties of the laser light due to self-mixing with reflections from the object are present in the primary radiation received by the photodiode, which, when reverse biased, can generate a measurable electrical parameter having a value related to the changed properties of the primary radiation, from which the distance or motion of the object can be inferred.

[0044] In some embodiments described herein, the photodiode is integrally formed, for example using epitaxial deposition techniques, on a semiconductor substrate on which the VCSEL is formed. The photodiode may be disposed between the semiconductor substrate and the VCSEL diode, or the VCSEL diode may be disposed between the semiconductor substrate and the photodiode. Various electrical connections may be formed in or on the substrate, the VCSEL diode, and / or the photodiode, for example, to bias the VCSEL diode, to receive a signal from the photodiode, or to receive other electrical signals. The VCSEL diode may have an input current (or voltage) modulated to provide modulation of the primary radiation. Such modulation of the primary radiation may allow the distance and motion of a target to be inferred.

[0045] To improve the efficiency of absorption of the primary radiation into the laser cavity of the VCSEL diode, additional photodetector structures may be formed within the resonant cavity of the VCSEL diode, such as one or more gain stage layers, including, but not limited to, an indium gallium arsenide (InGaAs) layer, an aluminum gallium arsenide (AlGaAs) layer, etc. Additionally, depending on the polarity of the junction, a tunnel junction may be inserted between the photodiode junction of the photodiode and the laser junction of the VCSEL diode to improve carrier injection and extraction and reduce the operating voltage of the optoelectronic sensing device.

[0046] In some embodiments, a multi-junction structure consisting of multiple active regions (e.g., multiple pairs of barrier layers alternating with quantum well layers) and heavily doped tunnel junctions interspersed between them can be stacked vertically within the resonant cavity of a VCSEL diode. The multi-junction structure can have one or more oxide layers formed on the top, bottom, or in between. Such a multi-junction (MJ) VCSEL diode can emit laser light with characteristics different from those emitted by a comparable single-junction (SJ) VCSEL diode operating at a similar current level. The multi-junction structure allows the MJ VCSEL diode to operate at increased voltage levels (compared to a similar SJ VCSEL diode operating at a similar current level), providing multiple factors of increased gain in output power, for example. Also, the center frequency of the emitted laser light can be increased, which can improve the signal-to-noise ratio (SNR) by reducing 1 / f noise. The increased SNR and higher operating frequencies can also enable improved spatial resolution of targets by optoelectronic sensing devices utilizing MJ VCSEL diodes due to the increased efficiency and tunability range for wavelength modulation of the emitted laser light by the MJ VCSEL diodes, which in turn enables better measurement of electrical parameters associated with the self-mixing interference of the emitted laser light. Thus, the multi-junction structure improves the performance of optoelectronic sensing devices through faster signal propagation, wider sampling, and reduced complexity.

[0047] In some embodiments, the optoelectronic sensing device having a multi-junction structure may also have an extended resonant cavity that extends from the VCSEL diode to an on-chip lens (OCL) formed at the back end of the substrate, including the substrate. The extended resonant cavity significantly reduces the laser linewidth and extends the laser coherence length required for long-range sensing.

[0048] In some embodiments, the optoelectronic sensing device may have a semiconductor wafer or chip disposed on its surface and defining a set of mesas, at least some of the mesas including a VCSEL diode with an integrated photodiode. The VCSEL diode is configured to emit a primary radiation of laser light from an active region surrounding its laser cavity toward the substrate through the backside when forward biased. The photodiode may be an RCPD having an active region offset from the active region of the VCSEL diode. The RCPD is configured to detect self-mixing interference of the primary radiation upon receiving reflection or backscattering of the primary radiation when reverse biased. Adjacent mesas are connected to a power source and to each other via one or more electrical conductors.

[0049] Although particular optoelectronic sensing devices are shown in the figures and described below, the embodiments described herein may be used with a variety of electronic devices, including, but not limited to, mobile phones, personal digital assistants, timing devices, health monitoring devices, wearable electronic devices, input devices (e.g., styluses), desktop computers, electronic glasses, etc. Although a variety of electronic devices are mentioned, the optoelectronic sensing devices of the present disclosure may also be used with other products and combined with a variety of materials.

[0050] These and other embodiments are described below with reference to Figures 1-12. However, those skilled in the art will readily appreciate that the detailed description provided herein with respect to these figures is for illustrative purposes only and should not be construed as limiting.

[0051] FIG. 1 shows a cross-sectional view of a first exemplary structure 100 of a back-emitting vertical-cavity surface-emitting laser (VCSEL) diode 120 integrated with a resonant cavity photodetector (RCPD) 130, which is disposed in the path of secondary radiation away from the primary radiation 140 of the VCSEL diode 120. The VCSEL diode 120 is formed on a semiconductor substrate 110, such as by epitaxial deposition techniques. The VCSEL diode 120 includes a first active region 128 having one or more quantum well structures. The first active region 128 forms a heavily doped pn junction that, when forward biased, allows charge carriers to cross the pn junction and induce the primary radiation 140 of laser light therefrom towards the substrate 110. On either side of the first active region 128 are distributed Bragg diffraction layers formed as alternating semiconductor layers of high and low refractive index, which can act as mirrors in the resonant cavity of the VCSEL diode 120.

[0052] This primary radiation 140, upon reflection and backscattering from the target object 150, is received within the laser cavity of the first active region 128 where it undergoes self-mixing interference, resulting in a change in the electrical properties of the VCSEL diode 120 and / or the primary radiation 140.

[0053] The RCPD 130 is formed on the VCSEL diode 120, such as by epitaxial deposition techniques, and includes a second active region 138. The RCPD 130 receives the laser light of the VCSEL diode 120 with a changed electrical property. The second active region 138 is configured to detect the changed electrical property of the self-mixed laser light of the VCSEL diode 120 when reverse biased, and generate an output signal that is dependent on the wavelength of the self-mixed primary radiation of the VCSEL diode 120. The distance or movement of a target object 150 that reflects or backscatters the primary radiation 140 can be determined based on the output signal from the RCPD 130.

[0054] FIG. 2 shows a cross-sectional view of a second exemplary structure 200 of a back-emitting vertical-cavity surface-emitting laser (VCSEL) diode 220 integrated with a resonant-cavity photodetector (RCPD) 130, where the RCPD 230 is positioned along the primary emission 240 of the VCSEL diode 220.

[0055] The RCPD 230 is formed on the semiconductor substrate 210, such as by epitaxial deposition techniques, and includes a first active region 238. The VCSEL diode 220 is formed on the RCPD 230, also by epitaxial deposition techniques. The VCSEL diode 220 includes a second active region 228 having one or more quantum well structures. The second active region 228 forms a heavily doped pn junction that, when forward biased, allows charge carriers to traverse the pn junction and induce primary emission 240 of laser light therefrom towards the substrate 210. On either side of the second active region 228 are distributed Bragg diffraction layers formed as alternating semiconductor layers of high and low refractive index that can act as mirrors in the resonant cavity of the VCSEL diode 220.

[0056] This primary radiation 240, upon reflection and backscattering from the target object 250, is received into the laser cavity of the second active region 228 where it undergoes self-mixing interference, resulting in a change in the electrical properties of the VCSEL diode 220 and / or the primary radiation 240.

[0057] The RCPD 230 also receives the laser light of the VCSEL diode 220 with the altered electrical properties. The first active region 238, when reverse biased, is configured to detect the altered electrical properties of the self-mixed laser light of the VCSEL diode 220 and generate an output signal that is dependent on the wavelength of the self-mixed primary radiation 240 of the VCSEL diode 220. Based on the output signal from the RCPD 230, the distance or movement of the target object 250 receiving the primary radiation 240 can be determined.

[0058] 3 illustrates a cross-sectional view of an exemplary optoelectronic sensing device 300 having a first exemplary structure 100 of a backside-emitting VCSEL diode integrated with an RCPD (shown in FIG. 1 ). In particular, the backside-emitting VCSEL diode 302 is integrated with an RCPD 312 that is positioned under forward bias, away from the primary radiation 340 generated from the VCSEL diode 302, and in the path of the secondary radiation. The RCPD 312 receives the modified primary radiation from the VCSEL diode 302 after the primary radiation 340 has undergone self-mixing interference upon receiving reflection or backscattering therein.

[0059] The optoelectronic sensing device 300 is fabricated by first depositing a set of stacked semiconductor layers on a surface 308f of a substrate 308 to form a VCSEL diode 302, and then forming an RCPD 312 on the VCSEL diode 302. An on-chip lens 330 is disposed on a rear surface 308r of the substrate 308 and configured to collimate, focus, or expand the laser light emitted by the VCSEL diode 302, and collect the returning laser light back into the laser cavity of the first active region 302 in the VCSEL diode 302 for coherent mixing.

[0060] The VCSEL diode 302 may include an emission-side (or "top") distributed Bragg reflector (hereinafter "DBR") layer 303a that functions as the first (or "emission-side") mirror of the laser structure. The emission-side DBR layer 303a may include a set of pairs of alternating materials having different refractive indices. Each such pair of alternating materials is referred to herein as a Bragg pair. One or more materials in the emission-side DBR layer 303a may be doped to be p-type, and thus form part of the anode portion of the pn diode junction of the VCSEL diode 302. An exemplary pair of materials that may be used to form the emission-side DBR layer 303a is aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs).

[0061] The VCSEL diode 302 can also include a base-side DBR layer 303b that functions as the second (or “base side” or “bottom side”) mirror of the laser. The base-side DBR layer 303b can also include a set of Bragg pairs of alternating materials having different refractive indices. One or more materials within the base-side DBR layer 303b may be doped to be n-type and thus form part of the cathode portion of the p-n diode structure. Exemplary pairs of materials that can be used to form the base-side DBR layer 303b are aluminum arsenide (AlAs) and GaAs.

[0062] In some embodiments, the DBR layers 303a and 303b may be formed from semiconductor epitaxy and either semiconductor GaAs, AlxGa1-xAs for (0 < x ≤ 1), or other semiconductor materials. In other embodiments, the DBR layers 303a and 303b may be formed from dielectric materials. Examples of such dielectrics include, but are not limited to, amorphous silicon (a-Si), silicon dioxide (SiO2), SiO2 / niobium pentoxide (Nb2O5), and SiO2 / tantalum pentoxide (Ta2O5). In still other embodiments, the DBR layers 303a and 303b may be formed as a hybrid of semiconductor materials and dielectric materials.

[0063] The VCSEL diode 302 can include an active region 307 that functions partially as a resonant cavity. In a laser diode such as the VCSEL diode 302, the active region 307 can include one or more quantum wells. In some embodiments as shown in FIG. 3, the active region 307 of the VCSEL diode 302 may be adjacent to an oxide layer 309 having an opening through which the primary emission 340 escapes. In some embodiments as shown in FIG. 3, the active region 307 further includes one or more gain layers 304 (e.g., InGaAs layer, AlGaAs layer) formed within the resonant cavity of the VCSEL diode 302 to improve the absorption efficiency of the primary emission 340.

[0064] The VCSEL diode 302 may be formed by epitaxial growth of layers for each of the emission side layer 303a and base side DBR layer 303b, the active region 307 and oxide layer 309, and possibly other layers. These various layers may be formed by epitaxial growth on a substrate 308. Power contacts 305a, 305b may be formed on the emission side and base side layers of the VCSEL diode 302.

[0065] The RCPD 312 is formed on the VCSEL diode 302. In some embodiments, the RCPD 312 can include an active region 314 (offset from the active region 307 of the VCSEL diode 302) and a feed contact 315a. The active region 314 can include one or more gain layers (e.g., InGaAs layers, AlGaAs layers) to improve the absorption efficiency of the altered primary radiation 340 after undergoing self-mixing interference in the active region 307 of the VCSEL diode 302. The feed contact 315a forms a ring or horseshoe connection on the top side of the RCPD 312. The grating structure 320 can be vertically disposed on a set of stacked semiconductor layers forming the RCPD 312, as will be further described with respect to FIG. 4.

[0066] One or more tunnel junctions 310 and additional gain layers 311 may be disposed between the active region 307 of the VCSEL diode 302 and the active region 314 of the RCPD 312. Depending on the polarity of the junction, the tunnel junctions 310 may improve carrier injection / extraction from the VCSEL diode 302 to the RCPD 312 and help reduce the operating voltage of the optoelectronic sensing device 300.

[0067] As an example, in one embodiment, the tunnel junction 310 of the VCSEL diode 302 may have a turn-on voltage (forward bias voltage at which lasing begins) of approximately 1.3 V, so the resulting turn-on voltage of the VCSEL diode 302 overall is approximately 2.6 V. However, the current remains constant for a single tunnel junction, which in one embodiment is 0.5 mA.

[0068] The tunnel junction 310 of the VCSEL diode 302 may be formed with both a heavily doped n-type layer and a heavily doped p-type layer. Examples of n-type dopants include, but are not limited to, silicon (Si), tellurium (Te), and selenium (Se). Examples of p-type dopants include, but are not limited to, carbon (C), zinc (Zn), and beryllium (Be). The heavily doped concentration values ​​are at least 10 18 / cm 3 For some dopants, the doping concentration may be as high as 10 20 / cm 3 The concentration may be as high as 100 mg / kg, but other concentrations are possible.

[0069] As shown in FIG. 3, a current I flows through the VCSEL diode 302 between a common feed contact 305a (shared with the RCPD 312) and the feed contact 305b of the VCSEL diode 302. LD 306 generates a forward bias that generates a primary radiation 340 that is directed through the substrate 308 and the on-chip lens 330 to the target object 350. At the same time, a current I flows through the RCPD 312 between the common feed contact 305a (shared with the VCSEL diode 302) and the feed contact 315a of the RCPD 312. PD 316 generates a reverse bias through the RCPD 312. One or more controllers, such as a processor 1204 described below with respect to FIG. 12, can be communicatively coupled to the optoelectronic sensing device 300 to enable configuration for forward biasing the VCSEL diode 302 and the RCPD 312.

[0070] When the VCSEL diode 302 is forward biased, the laser light of the primary radiation 340 undergoes self-mixing interference within the laser cavity of the active region 307 upon its reflection or backscattering. The RCPD 312 receives the self-mixed primary radiation 340 and detects the changed electrical properties of the primary radiation 340 upon reverse biasing. In some embodiments, one or more controllers may be configured to switch the bias polarity of the RCPD 312 to capture multiple detections of the self-mixing interference in the time domain for time-multiplexed sample readout, as described with respect to FIG.

[0071] 4 shows a cross-sectional view of a grating structure 320 configured to be disposed on a set of stacked semiconductor layers, such as, but not limited to, a substrate forming the exemplary optoelectronic sensing device 300 of FIG. 3 or the exemplary optoelectronic sensing device 700 of FIG. 7, described below. The grating structure 320 may be a diffraction grating structure having a grating period greater than the wavelength of the primary radiation. Alternatively, the grating structure 320 may be a sub-wavelength grating structure having a grating period less than the wavelength of the primary radiation. The grating structure 320 is an optional feature that may have different structural variations of the features described below, and may or may not be incorporated into the optoelectronic sensing device depending on design requirements, such as, but not limited to, stabilizing the polarization of the emitted laser light.

[0072] The grating structure 320 is disposed on top of a set of stacked semiconductor layers that may also include a feed contact (e.g., feed contact 315a in FIG. 3) that forms a ring or horseshoe around the grating structure 320. The grating structure 320 has a base layer 322 formed (e.g., using atomic layer deposition) by laterally alternating a high refractive index grating material 323 (e.g., amorphous silicon, GaAs) and a low refractive index grating material 324 (e.g., a dielectric material such as silicon oxide, aluminum oxide, silicon nitride, etc.). An optional dielectric stack 326 of alternating DBR and dielectric layers (e.g., silicon oxide, aluminum oxide, silicon nitride) may be disposed on the base layer 322. The set of DBR layers in the dielectric stack 326 aids in optical reflection of laser light from a VCSEL diode (e.g., the VCSEL diode 302 of the optoelectronic sensing device 300). The grating structure 320 has a conductive layer 328 formed from a metal (e.g., gold, copper) disposed on top of an optional dielectric stack 326. The top layer 328 electrically connects the power contacts of the VCSEL diodes and / or RCPDs, enhances optical reflection of the emitted laser light, stabilizes the optional polarization of the emitted laser light, and also serves to bond the grating structure 320 to other materials.

[0073] 5A-5D show schematic diagrams of the operating circuitry in the exemplary optoelectronic sensing device 300 of FIG. 3. In FIG. 5A, the VCSEL diode 302 may be forward biased between a first bias node 512 and a common node 514, and the RCPD 312 may be reverse biased between the common node 514 and a second bias node 516. By way of example, the first bias node 512 may be driven to a positive voltage such as 0.2V, the common node 514 may be driven to a positive voltage such as 3V, and the second bias node 516 has a positive voltage such as 1.5V. The voltage of the second bias node 516 may depend on a transimpedance amplifier (TIA) or other readout circuit connected thereto. In different embodiments, different voltage levels may be used for the first bias node 512, the common node 514, and the second bias node 516, and generally the voltage at the second bias node 516 is between the voltage at the first bias node 512 and the voltage at the common node 514. Forward biasing the VCSEL diode 302 can drive a cathode load current that causes the primary radiation 340 to be emitted therefrom. Reverse biasing the RCPD 312 can cause the RCPD 312 to generate a photocurrent when it receives the primary radiation 340 whose characteristics have changed due to self-mixing in the VCSEL diode 302. This photocurrent can be detected by a transimpedance amplifier (TIA) connected to the second bias node 516. In the configuration shown in FIG. 5A, the common node 514 has an n-contact and a tunnel junction exists between the VCSEL diode 302 and the RCPD 312.

[0074] 5B, the VCSEL diode 302 may be forward biased between a first bias node 522 and a common node 524, and the RCPD 312 may be reverse biased between a common node 524 and a second bias node 526. By way of example, the first bias node 522, the common node 524, and the second bias node 526 may be driven to progressively less positive voltages such that the voltage at the common node 524 is generally between the voltage at the first bias node 522 and the voltage at the second bias node 526. The voltage at the second bias node 526 may depend on a transimpedance amplifier (TIA) or other readout circuitry connected thereto. In different embodiments, different sets of positive voltage levels may be used for the first bias node 522, the common node 524, and the second bias node 526, but in the example shown in FIG. 5B, the first bias node 522 may be driven to 4.3V, the common node 524 may be driven to 1.7V, and the second bias node 526 may have 0.2V. Forward biasing the VCSEL diode 302 may drive an anode current that causes the primary radiation 340 to radiate therefrom. Reverse biasing the RCPD 312 may cause the RCPD 312 to generate a photocurrent when it receives the primary radiation 340 whose characteristics have changed due to self-mixing in the VCSEL diode 302. This photocurrent may be detected by a TIA connected to the second bias node 526. In the configuration shown in FIG. 5A, the common node 524 has an n-contact.

[0075] In FIG. 5C, the VCSEL diode 302 may be forward biased between the first bias node 532 and the common node 534, and the RCPD 312 may be reverse biased between the common node 534 and the second bias node 536. As an example, the first bias node 532 may be driven to a positive voltage such as 2.6V, the common node 534 may be held at 0V or ground (GND), and the second bias node 836 may have a positive voltage such as 1.5V. The voltage of the second bias node 536 may depend on a transimpedance amplifier (TIA) or other readout circuit connected thereto. In different embodiments, different voltage levels may be used for the first bias node 532, the common node 534, and the second bias node 536, and generally the voltage at the second bias node 536 is between the voltage at the first bias node 532 and the voltage at the common node 534. Forward biasing the VCSEL diode 302 can drive an anode current that causes primary radiation 340 to be emitted therefrom. Reverse biasing the RCPD 312 can cause the RCPD 312 to generate a photocurrent when it receives primary radiation 340 whose characteristics have changed due to self-mixing in the VCSEL diode 302. This photocurrent can be detected by a TIA connected to a second bias node 536. In the configuration shown in FIG. 5C, the common node 534 has an n-contact and a native reverse junction exists between the VCSEL diode 302 and the RCPD 312.

[0076] 5D, the VCSEL diode 302 may be forward biased between a first bias node 542 and a common node 544, and the RCPD 312 may be reverse biased between a second bias node 546 and the common node 544. By way of example, the first bias node 542, the common node 544, and the second bias node 546 may be driven to progressively more positive voltages such that the voltage at the common node 544 is generally between the voltage at the first bias node 542 and the voltage at the second bias node 546. The voltage at the second bias node 546 may depend on a transimpedance amplifier (TIA) or other readout circuitry connected thereto. In different embodiments, different sets of positive voltage levels may be used for the first bias node 542, the common node 544, and the second bias node 546, but in the example shown in FIG. 5D, the first bias node 542 may be held at 0V or ground (GND), the common node 544 may be driven to a positive voltage of 2.6V, and the second bias node 546 may have a positive voltage of 4.1V. Forward biasing the VCSEL diode 302 may drive a cathode load current that causes the primary radiation 340 to radiate therefrom. Reverse biasing the RCPD 312 may cause the RCPD 312 to generate a photocurrent when it receives the primary radiation 340 whose characteristics have changed due to self-mixing in the VCSEL diode 302. This photocurrent may be detected by a TIA connected to the second bias node 546. In the configuration shown in FIG. 5A, the common node 544 has a p-contact.

[0077] 6 shows a schematic diagram of an operating circuit in the exemplary optoelectronic sensing device 300 of FIG. 3, in which the bias polarity of the RCPD 312 is switched in the time domain. In FIG. 6, the VCSEL diode 302 may be forward biased between the first bias node 612 and the common node 614, and the RCPD 312 may be reverse biased or forward biased between the common node 614 and the second bias node 616. In different embodiments, different voltage levels may be used for the first bias node 612, the common node 614, and the second bias node 616. By forward biasing the VCSEL diode 302, a cathode load current may be driven, which causes a primary radiation 340 to be emitted therefrom, which is received by the RCPD 312, which changes its characteristics due to self-mixing in the VCSEL diode 302, which then generates a photocurrent. This photocurrent may be detected by the TIA connected to the second bias node 616. The bias polarity of the RCPD 312 may be switched in the time domain, which allows for time-multiplexed sample readout of the photocurrent.

[0078] 7 illustrates a cross-sectional view of an exemplary optoelectronic sensing device 700 having the second exemplary structure 200 of a backside-emitting VCSEL diode integrated with an RCPD (shown in FIG. 2). In particular, a backside-emitting VCSEL diode 702 is integrated with an RCPD 712 that is positioned under forward bias along the path of a primary radiation 740 of laser light generated from the VCSEL diode 702. The RCPD 712 receives the modified primary radiation from the VCSEL diode 702 after the primary radiation 740 undergoes self-mixing interference upon receiving reflection or backscattering therein.

[0079] The optoelectronic sensing device 700 is fabricated by first depositing a set of mirror layers 710 on a surface 708f of a substrate 708. In some embodiments, the set of mirror layers 710 may be DBR layers as described above. A power supply contact 715a may be disposed on the top surface of the set of mirror layers 710 and may form a ring or horseshoe connection around the RCPD 712 deposited on the set of mirror layers 710. An on-chip lens 730 is disposed on a rear surface 708r of the substrate 708 and configured to collimate the laser light emitted by the VCSEL diode 702 and reflect a portion of the primary radiation back towards a first active region in the VCSEL diode 702 and the RCPD 712.

[0080] The RCPD 712 is epitaxially deposited on the set of mirror layers 710. In some embodiments, the RCPD 712 may include an active region 714 and a feed contact 715b disposed on its top surface. The active region 714 may include one or more gain layers (e.g., InGaAs layers, AlGaAs layers) to improve the absorption efficiency of the altered primary radiation 740 after undergoing self-mixing interference in the active region 707 of the VCSEL diode 302. The feed contact 715b forms a ring or horseshoe connection on the top side of the RCPD 312.

[0081] The VCSEL diode 702 is formed on the RCPD 712, such as by epitaxial deposition techniques. The VCSEL diode 702 may include an emission-side (or "top") DBR layer 703a that functions as a first (or "emission-side") mirror of the laser structure. The emission-side DBR layer 703a may include a set of pairs of alternating materials having different refractive indices. One or more materials in the emission-side DBR layer 703a may be doped to be p-type, and thus form part of the anode portion of the pn diode junction of the VCSEL diode 702. An exemplary pair of materials that may be used to form the emission-side DBR layer 703a is AlGaAs and GaAs.

[0082] The VCSEL diode 702 can also include a base-side DBR layer 703b that functions as the second (or "base side" or "bottom side") mirror of the laser. The base-side DBR layer 703b can also include a set of Bragg pairs of alternating materials having different refractive indices. One or more materials within the base-side DBR layer 703b may be doped to be n-type and thus form part of the cathode portion of the p-n diode structure. An exemplary pair of materials that can be used to form the base-side DBR layer 703b are AlAs and GaAs.

[0083] In some embodiments, the DBR layers 703a and 703b can be formed from semiconductor epitaxy, as well as semiconductor GaAs, Al x Ga 1-x As, or any other semiconductor material for (0 < x ≤ 1). In other embodiments, the DBR layers 703a and 703b can be formed from dielectric materials. Examples of such dielectrics include, but are not limited to, amorphous silicon (a-Si), silicon oxide (SiO2), SiO 2 / Nb2O5, and SiO2 / Ta2O5. In yet other embodiments, the DBR layers 703a and 703b can be formed as a hybrid of semiconductor materials and dielectric materials.

[0084] The VCSEL diode 702 can include an active region 707 that functions partially as a resonant cavity. In a laser diode such as the VCSEL diode 702, the active region 707 can include one or more quantum wells. In some embodiments as shown in FIG. 7, the active region 707 of the VCSEL diode 702 may be adjacent to an oxide layer 709 having an opening through which the primary emission 740 escapes. In some embodiments as shown in FIG. 7, the active region 707 further includes one or more gain layers 704 (e.g., InGaAs layer, AlGaAs layer) formed within the resonant cavity of the VCSEL diode 702 to improve the absorption efficiency of the primary emission 740.

[0085] The VCSEL diode 702 may be formed by epitaxial growth of each of the emission-side and base-side DBR layers 703a and 703b, the active region 707, and the oxide layer 709, and possibly other layers. These various layers may be formed by epitaxial growth on the RCPD 712. A feed contact 705a may be formed on the emission-side and base-side layers of the VCSEL diode 702. A lattice structure 320 may be disposed on the VCSEL diode 702, as will be further described with respect to FIG.

[0086] One or more tunnel junctions (such as tunnel junction 310 described with respect to FIG. 3) and additional gain layers (such as tunnel junction 311 described with respect to FIG. 3) may be disposed between the active region 707 of the VCSEL diode 702 and the active region 714 of the RCPD 712. Depending on the polarity of the junctions, such tunnel junctions may improve carrier injection / extraction from the VCSEL diode 702 to the RCPD 712 and help reduce the operating voltage of the optoelectronic sensing device 700.

[0087] As shown in FIG. 7, a current I flows through the VCSEL diode 702 between the feed contact 705a of the VCSEL diode 702 and the common feed contact 715b (shared with the RCPD 712). LD 706 generates a forward bias that generates primary radiation 740 that is directed through the substrate 708 and the on-chip lens 730 to the target object 750. At the same time, a current I flows through the RCPD 312 between the common feed contact 715b (shared with the VCSEL diode 702) and the feed contact 715a of the RCPD 712. PD 716 generates a reverse bias through the RCPD 712. One or more controllers, such as a processor 1204 described below with respect to FIG. 12, can be communicatively coupled to the optoelectronic sensing device 700 to enable configuration for forward biasing the VCSEL diode 702 and the RCPD 712.

[0088] When the VCSEL diode 702 is forward biased, the laser light of the primary radiation 740 undergoes self-mixing interference within the laser cavity of the active region 707 upon reflection or backscattering thereof. The RCPD 712 receives the self-mixed primary radiation 740 and detects the changed electrical properties of the primary radiation 740 upon reverse bias.

[0089] 8A-8D show schematic diagrams of the operating circuitry in the exemplary optoelectronic sensing device 700 of FIG. 7. In FIG. 8A, the VCSEL diode 702 may be forward biased between a first bias node 812 and a common node 814, and the RCPD 712 may be reverse biased between the common node 814 and a second bias node 816. By way of example, the first bias node 812 may be driven to a positive voltage such as 2.6V, the common node 814 may be held at 0V or ground (GND), and the second bias node 816 may have a positive voltage such as 1.5V. The voltage of the second bias node 816 may depend on a transimpedance amplifier (TIA) or other readout circuitry connected thereto. In different embodiments, different voltage levels may be used for the first bias node 812, the common node 814, and the second bias node 816. Forward biasing the VCSEL diode 702 may provide an anode drive current that causes primary radiation 740 to be emitted therefrom. By reverse biasing the RCPD 712, a photocurrent can be generated when the RCPD 712 receives primary radiation 740 whose characteristics have been altered due to self-mixing in the VCSEL diode 702. This photocurrent can be detected by a TIA connected to a second bias node 816. In the configuration shown in FIG. 8A, the common node 814 has an n-contact and a native reverse junction is formed between the VCSEL diode 702 and the RCPD 712.

[0090] In FIG. 8B, the VCSEL diode 702 may be forward biased between the first bias node 822 and the common node 824, and the RCPD 712 may be reverse biased between the common node 824 and the second bias node 826. As an example, the first bias node 822, the common node 824, and the second bias node 826 may be driven to progressively lower positive voltages. The voltage of the second bias node 826 may depend on a transimpedance amplifier (TIA) or other readout circuitry connected to it. In different embodiments, different sets of positive voltage levels may be used for the first bias node 822, the common node 824, and the second bias node 826, but in the example shown in FIG. 8B, the first bias node 822 may be driven to 4.3V, the common node 824 may be driven to 1.7V, and the second bias node 826 may have 0.2V. By forward biasing the VCSEL diode 702, an anode current can be driven, which causes primary radiation 740 to be emitted therefrom. By reverse biasing the RCPD 712, a photocurrent can be generated when the RCPD 712 receives primary radiation 740 whose characteristics have been altered due to self-mixing in the VCSEL diode 702. This photocurrent can be detected by a TIA connected to a second bias node 826. In the configuration shown in FIG. 8A, the common node 824 has an n-contact.

[0091] In FIG. 8C, the VCSEL diode 702 may be forward biased between a first bias node 832 and a common node 834, and the RCPD 712 may be reverse biased between the common node 834 and a second bias node 836. By way of example, the first bias node 832 may be held at 0V or ground (GND), the common node 834 may be driven to a positive voltage of 2.8V, and the second bias node 836 may have a positive voltage such as 1.3V. The voltage of the second bias node 836 may depend on a transimpedance amplifier (TIA) or other readout circuitry connected thereto. In different embodiments, different voltage levels may be used for the first bias node 832, the common node 834, and the second bias node 836. Forward biasing the VCSEL diode 702 may drive a cathode load current that causes primary radiation 740 to radiate therefrom. By reverse biasing the RCPD 712, a photocurrent can be generated when the RCPD 712 receives primary radiation 740 whose characteristics have been altered due to self-mixing in the VCSEL diode 702. This photocurrent can be detected by a TIA connected to a second bias node 836. In the configuration shown in FIG. 8C, the common node 834 has an n-contact and a tunnel junction exists between the VCSEL diode 702 and the RCPD 712.

[0092] In FIG. 8D, the VCSEL diode 702 may be forward biased between the first bias node 842 and the common node 844, and the RCPD 712 may be reverse biased between the second bias node 846 and the common node 844. As an example, the first bias node 842, the common node 844, and the second bias node 846 may be driven to progressively more positive voltages. The voltage of the second bias node 846 may depend on a transimpedance amplifier (TIA) or other readout circuitry connected to it. In different embodiments, different sets of positive voltage levels may be used for the first bias node 842, the common node 844, and the second bias node 846, but in the example shown in FIG. 8D, the first bias node 842 may be held at 0V or ground (GND), the common node 844 may be driven to 2.6V, and the second bias node 846 may have 4.1V. The VCSEL diode 702 can be forward biased to drive a cathode load current that causes primary radiation 740 to be emitted therefrom. The RCPD 712 can be reverse biased to generate a photocurrent when the RCPD 712 receives primary radiation 740 whose characteristics have been altered due to self-mixing in the VCSEL diode 702. This photocurrent can be detected by a TIA connected to a second bias node 846. In the configuration shown in FIG. 8A, the common node 844 has a p-contact.

[0093] 9A-9B respectively show a cross-sectional view and corresponding schematic diagram of an operating circuit of a first exemplary optoelectronic sensing device 900 having an extended resonant cavity on the emission side of a back-emitting VCSEL diode with a multi-junction structure (MJ-VCSEL), as described below. The extended resonant cavity extends from the VCSEL diode to an on-chip lens (OCL) 930 formed on a rear surface 908r of the substrate 908 and includes the substrate 908. In particular, FIG. 9A shows a back-emitting MJ-VCSEL diode 902 integrated with an RCPD 912 positioned away from the path of the primary emission 940 of the laser light from the MJ-VCSEL diode 902 under forward bias. The RCPD 912 receives the modified primary emission 940 from the MJ-VCSEL diode 902 after the primary emission 940 undergoes self-mixing interference upon receiving reflection or backscattering therein.

[0094] The optoelectronic sensing device 900 is fabricated by first forming a substrate 908 (e.g., a low-loss semiconductor or dielectric material) with an extended cavity, depositing a set of stacked semiconductor layers on a surface 908f of the substrate 908 to form a MJ-VCSEL diode 902 with a multi-junction structure 901, and then forming an RCPD 912 on the VCSEL diode 902. As described above, the extended resonant cavity significantly reduces the laser linewidth and extends the laser coherence length required for long-distance sensing. An on-chip lens 930 is disposed on a rear surface 908r of the substrate 908 and configured to collimate the laser light emitted by the VCSEL diode 902 and collect the return laser light returning from the target object toward the VCSEL diode 902 and the first active region in the RCPD 912. A reflective coating 935 made of a dielectric material may be disposed on the on-chip lens 930.

[0095] 3, the MJ-VCSEL diode 902 may include an emission-side (or "top") DBR layer 903a that includes a set of pairs of alternating materials (e.g., AlGaAs, GaAs) having different refractive indices. The MJ-VCSEL diode 902 may also include a base-side DBR layer 903b that also includes a set of Bragg pairs of alternating materials (e.g., AlAs, GaAs) having different refractive indices. One or more of the materials in the emission-side DBR layer 903a and the base-side DBR layer 903b may be doped p-type and n-type, respectively, and thus form part of the anode and cathode portions of a pn diode structure, respectively.

[0096] Between the DBR layers 903a and 903b, the MJ-VCSEL diode 902 may have multiple active regions 907a, 907b, 907c (e.g., multiple pairs of barrier layers alternating with quantum well layers) that generate laser light when stimulated by a forward bias voltage. The multiple active regions 907a, 907b, 907c may be interspersed with heavily doped tunnel junctions 910a, 910b, 910c (similar to the tunnel junction 310 described above with respect to FIG. 3) to form a vertically stacked multi-junction structure 901 in the MJ-VCSEL diode 902. One or more gain layers 911a, 911b, 911c (similar to the gain layer 311 described above with respect to FIG. 3) may be coupled to the tunnel junctions 910a, 910b, 910c, respectively, in the multi-junction structure 901. It should be noted that while in the embodiment shown in FIG. 9A there are three active regions 907a-907c interspersed with three tunnel junctions 910a, 910b, 910c coupled to respective ones of three gain layers 911a, 911b, 911c, in other embodiments the MJ-VCSEL diode 902 may have two or more than three of each type of layer forming a vertical stack between the DBR layers 903a and 903b.

[0097] Generally, in MJ-VCSEL diodes having different numbers of active regions, there is a tunnel junction between each successive pair of active regions. As shown in FIG. 9A, in MJ-VCSEL diode 902, there is a first tunnel junction 910a between active regions 907a and 907b, and a second tunnel junction 910b between active regions 907b and 907c. Optionally, MJ-VCSEL diode 902 can also include one or more tunnel junctions at locations other than between successive pairs of active regions 907a-907c, such as tunnel junction 910c between active region 907c and RCPD 912. The tunnel junctions 910a-910c of MJ-VCSEL diode 902 can be of the same type or different types. Semiconductor materials that can be used for the tunnel junction layer include GaAs (0 < x ≦ 1, 0 < y < 1), Al x Ga 1-x As, In x Ga 1-x As, In x Ga 1-x P, GaAs 1-x N x 、In x Ga 1-x As y P 1-y 、and others known to those skilled in the art. Depending on the polarity of the junction, the tunnel junctions 910a-910c help improve carrier injection / extraction from MJ-VCSEL diode 902 to RCPD 912 and reduce the operating voltage of optoelectronic sensing device 900.

[0098] Each of the active regions 907a-c includes a plurality of barrier layers and quantum well layers. Materials that can be used for the barrier layers of the active regions 907a-c include Al x Ga 1-x As (0 < x ≦ 1), GaAs 1-x P x (0 < x ≦ 1), and others known to those skilled in the art. Materials that can be used for the quantum wells of the active regions 907a-c include In x Ga 1-x As (0 < x ≦ 1), In x Ga 1-x As y N 1-y, (0 < x ≤ 1, 0 < y ≤ 1), In x Ga 1-x As 1-y-z N y Sb z (0 < x ≤ 1, 0 < y < 1, 0 < z < 1, y + z < 1), and others known to those skilled in the art are included.

[0099] The MJ-VCSEL diode 902 includes a radiation-side (or "upper") oxide layer 909a disposed adjacent to the uppermost active region 907a or on the upper surface of the MJ-VCSEL diode 902, and a base-side (or "bottom") oxide layer 909c disposed adjacent to the lowermost active region 907c or on the bottom surface of the MJ-VCSEL diode 902. The oxide layer 909c includes an opening (or openings) through which the primary radiation 940 escapes. The MJ-VCSEL diode 902 can also include an additional oxide layer 909b adjacent to the active region 907b. Each of the oxide layers 909a and 909b includes an opening (or openings) that allows the primary radiation 940 to pass between the active regions 907a - 907c. Other embodiments of the MJ-VCSEL diode may not have an oxide layer between consecutive active regions, or may have two or more. The openings in the oxide layers 909a - c allow the laser light generated within the active regions 907a - 907c to pass through each other, and can enhance the generation of the primary radiation 940 of the laser light emitted through the optoelectronic sensing device 900.

[0100] In some embodiments as shown in FIG. 9A, each of the active regions 907a - 907c further includes one or more gain layer segments 904 (e.g., InGaAs layer, AlGaAs layer) formed within the resonant cavity of the MJ-VCSEL diode 902 to improve the efficiency of reabsorption of the primary radiation 940 into the MJ-VCSEL diode 902.

[0101] The MJ-VCSEL diode 902 may be formed by epitaxially growing the emitter-side DBR layer 903a, the multi-junction structure 901, and the base-side DBR layer 903b on a substrate 908. The RCPD 912 is then also formed on the MJ-VCSEL diode 902. In some embodiments, the RCPD 912 may include an active region 914, which may include one or more gain layers (e.g., InGaAs layers, AlGaAs layers) to improve the absorption efficiency of the altered primary radiation 940 after undergoing self-mixing interference in the active regions 907a-907c of the VCSEL diode 902. The grating structure 320 may be vertically disposed on a set of stacked semiconductor layers forming the RCPD 912, as will be further described with respect to FIG. 4.

[0102] The MJ-VCSEL diode 902 may have a common feed contact 905a (shared with the RCPD 912) disposed on or adjacent to the base-side DBR layer 903b, a first feed contact 905b disposed on or adjacent to the emission-side DBR layer 903a, and a second feed contact 915a disposed on the RCPD 912. The common feed contact 905a, the first feed contact 905b, and the second feed contact 915a may form ring or horseshoe connections around the base-side DBR layer 903b, the emission-side DBR layer 903a, and the RCPD 912, respectively.

[0103] Apply a bias voltage and measure the laser diode current I LD 906 can be passed through the VCSEL diode 902 between the common feed contact 905a and the first feed contact 905b to generate primary radiation 940. This generates primary radiation 940 that is directed through the substrate 908 and the on-chip lens 930 towards the target object 950. At the same time, a current I flows through the RCPD 912 between the common feed contact 905a and the second feed contact 915a of the RCPD 912. PD916 generates a reverse bias through the RCPD 912. One or more controllers, such as a processor 1204 described below with respect to FIG. 12, can be communicatively coupled to the optoelectronic sensing device 900 to enable configuration for forward biasing the VCSEL diode 902 and reverse biasing the RCPD 912.

[0104] When the VCSEL diode 902 is forward biased, the laser light of the primary radiation 940 undergoes self-mixing interference within the laser cavity of the active regions 907a-c upon reflection or backscattering thereof. The RCPD 912 receives the self-mixed primary radiation 940 and detects a changed electrical property of the primary radiation 940 upon reverse biasing.

[0105] The MJ-VCSEL diode 902 can emit laser light with characteristics different from those emitted by a single-junction VCSEL (SJ-VCSEL) diode 302 (shown in FIG. 3) operating at a similar current level. The MJ-VCSEL diode 902 can operate at an increased voltage level (compared to the SJ-VCSEL diode 302 operating at a similar current level), providing multiple factors of increased gain, for example, in output power. Also, the center frequency of the emitted laser light can be increased, which can improve the signal-to-noise ratio (SNR) because 1 / f noise is reduced. The increased SNR and higher operating frequency can also enable improved spatial resolution of a target by the optoelectronic sensing device 900 with the MJ VCSEL diode 902 due to the increased efficiency and tunability range for wavelength modulation of the emitted laser light by the MJ VCSEL diode 902, which in turn enables better measurement of electrical parameters associated with the self-mixing interference of the emitted laser light. Thus, the multi-junction structure 901 improves the performance of the optoelectronic sensing device 900 through faster signal propagation, wider sampling, and reduced complexity.

[0106] 9B, the VCSEL diode 902 may be forward biased between a first bias node 992 and a common node 994, and the RCPD 912 may be reverse biased between the common node 994 and a second bias node 996. By way of example, the first bias node 992 may be driven to a positive voltage such as 0.2V, the common node 994 may be driven to a positive voltage such as 6V, and the second bias node 996 may be driven to a positive voltage such as 4.5V. In different embodiments, different voltage levels may be used for the first bias node 992, the common node 994, and the second bias node 996. Forward biasing the VCSEL diode 902 may drive a cathode load current that causes primary radiation 940a-940c to radiate from a multi-junction structure 901 having active regions 907a-907c interspersed with tunnel junctions 910a-910c. By reverse biasing the RCPD 912, a photocurrent can be generated when the RCPD 912 receives primary radiation 940a-940c whose characteristics have been altered due to self-mixing in the VCSEL diode 902. This photocurrent can be detected by a TIA or another readout circuit connected to the second bias node 996. As mentioned above, the multi-junction structure 901 of FIG. 9A increases the thermal resistance as well as the tunability of the wavelength modulation for better measurement of the self-mixing interference.

[0107] 10A-10B respectively show a cross-sectional view and a corresponding schematic diagram of an operating circuit of a first exemplary optoelectronic sensing device 1000 having multiple sets of back-emitting VCSEL diodes (similar to the VCSEL diode 302 described with respect to FIG. 3) integrated with an RCPD (similar to the RCPD 312 described with respect to FIG. 3) positioned away from the primary emission path of the VCSEL diodes. The optoelectronic sensing device 1000 has a first arrangement of electrical connections between the multiple sets, as described below.

[0108] As shown in FIG. 10A, the optoelectronic sensing device 1000 is formed by forming an injection layer 1009 on a surface 1008f of a substrate 1008, and then forming a first set of mesas 10101, 10102, 10103 and a second set of mesas 10104, 10106, 10108, and 10109 on the surface 1008f of the substrate 1008.a , 1010 b , 1010 c 10A , a set of stacked semiconductor layers are deposited (e.g., by epitaxial deposition techniques) on the injection layer 1009 to form a set of emitters. Although a set of three mesas is shown in the embodiment of FIG. 10A , each set of mesas in different embodiments may include more or fewer mesas forming a respective number of emitters. Each of the mesas 10101, 10102, 10103 includes an individual backside-emitting VCSEL diode 10021, 10022, 10023 integrated with an individual RCPD 10121, 10122, 10123 disposed thereon. An individual lattice structure 10201, 10202, 10203 is disposed on each of the individual RCPDs 10121, 10122, 10123. Each of the mesas 10101, 10102, 10103 forms a respective emitter #1, emitter #2, emitter #3, whereby respective primary radiation 10401, 10402, 10403 is emitted by respective backside emitting VCSEL diodes 10021, 10022, 10023 through respective on-chip lenses 10301, 10302, 10303 disposed on the rear surface 1008r of the substrate 1008.

[0109] Each of the individual VCSEL diodes 10021, 10022, 10023 may include a respective active region 10071, 10072, 10073 (similar to active region 307 described with respect to FIG. 3) (not shown) which may include one or more quantum wells and may be adjacent to a respective oxide layer (not shown) having an opening through which the respective primary radiation 10401, 10402, 10403 escapes. The individual active regions 10071, 10072, 10073 may also include a respective gain stage layer 10041, 10042, 10043 (e.g., InGaAs layer, AlGaAs layer) (not shown) to improve the absorption efficiency of the respective primary radiation 10401, 10402, 10403. The individual RCPDs 101211012210123 may include respective active regions 10141, 10142, 10143, which may also include one or more gain layers (e.g., InGaAs layers, AlGaAs layers) to improve the absorption efficiency of the respective altered primary radiation 10401, 10402, 10403 after undergoing self-mixing interference in the respective active regions 10071, 10072, 10073 of the respective VCSEL diodes 10021, 10022, 10023. One or more tunnel junctions and gain layers may be disposed between the respective active regions 10071, 10072, 10073 of the respective VCSEL diodes 10021, 10022, 10023 and the respective active regions 10141, 10142, 10143 of the RCPDs 10121, 10122, 10123.

[0110] When the individual VCSEL diodes 10021, 10022, 10023 are forward biased, the laser light of the individual primary emissions 10401, 10402, 10403, upon reflection or backscattering, undergoes self-mixing interference within the individual active regions 10071, 10072, 10073. A corresponding one of the RCPDs 10121, 10122, 10123 receives the individual self-mixed primary emissions 10401, 10402, 10403 and detects the changed electrical properties of the individual self-mixed primary emissions 10401, 10402, 10403 when reverse biased.

[0111] In some embodiments, the first set of mesas 10101, 10102, 10103 and the second set of mesas 1010 a , 1010 b , 1010 c The first set of mesas 1010 may be formed by epitaxially growing a common set of semiconductor layers, forming trenches 1070, 1080 to define respective mesas, and then electrically connecting a selected number of the mesas to perform different functions or provide different routing structures. In the embodiment shown in FIG. 10A, the second set of mesas 1010 a , 1010 b , 1010 c Each one of the first group of adjacent mesas 10101, 10102, 10103 is adjacent to a respective one of the first set of mesas 10101, 10102, 10103 and is separated by a connecting trench 1070 (formed, for example, by etching through a set of stacked semiconductor layers). a The second group of adjacent mesas 10102, 10103 are separated by isolation trenches 1080 (also formed by etching through a set of stacked semiconductor layers) that penetrate the injection layer 1009 and provide electrical isolation between the respective active regions 10071, 10072, 10073 of the respective VCSEL diodes 10021, 10022, 10023. b A conductive layer 1060 (e.g., gold, copper) is disposed on the individual lattice structures 10201, 10202, 10203 on each of the RCPDs 10121, 10122, 10123, and the second set of mesas 1010 a , 1010 b , 1010 c , each of which is routed onto the other end to provide electrical connections across the set of mesas.

[0112] Each respective mesa 10101, 10102, 10103 includes a common feed contact 10051, 10052, 10053 that is shared between a corresponding VCSEL diode 10021, 10022, 10023 and an individual RCPD 10121, 10122, 10123 disposed thereon. As shown in FIG. 10A , a bias voltage applied via the individual common feed contact 10051, 10052, 10053 creates a forward bias (current I LD 1006 1、 1006 2、 10063) to generate individual primary radiation 10401, 10402, 10403 directed towards the target object 1050 through the substrate 1008 and the respective on-chip lenses 10301, 10302, 10303. At the same time, a reverse bias (current I PD 10161, 1016 2、 10163) serve to detect altered characteristics of the respective primary emissions 10401, 10402, 10403 due to self-mixing interference in the respective active regions 10071, 10072, 10073 of the individual VCSEL diodes 10021, 10022, 10023. One or more controllers, such as a processor 1204 described below with respect to FIG. 12, may be communicatively coupled to the optoelectronic sensing device 1000 to enable configuration for forward biasing the individual VCSEL diodes 10021, 10022, 10023 and reverse biasing the individual RCPDs 10121, 10122, 10123.

[0113] The particular arrangement of electrical connections in the optoelectronic sensing device 1000 with the conductive layer 1160 allows for individual addressability of each emitter formed by a respective one of the mesas 10101, 10102, 10103. As a result, any selection of one or more emitters, emitter #1, emitter #2, emitter #3, can be used as a sensor to detect distance, motion of a target object 1050 using self-mixing interference captured by individual back-emitting VCSEL diodes 10021, 10022, 10023 integrated with individual RCPDs 10121, 10122, 10123 disposed thereon.

[0114] 10B, each of the backside emitting VCSEL diodes 10021, 10022, 10023 may be forward biased between a first bias node 1092 and a common node 1094 (via common feed contacts 10051, 10052, 10053), and the individual RCPDs 10121, 10122, 10123 may be reverse biased between the common node 1094 and a second bias node 1096. The first bias node 1092 and the common node 1094 may have different positive voltages such that the individual VCSEL diodes 10021, 10022, 10023 are driven by cathode load currents that cause individual primary emissions 10401, 10402, 10403 to be emitted therefrom. The second bias node 1096 and the common node 1094 may also have different positive voltages, whereby the individual RCPDs 10121, 10122, 10123 are reverse biased such that a photocurrent is generated when the individual RCPDs 10121, 10122, 10123 receive the individual primary radiation 10401, 10402, 10403 that has changed characteristics due to self-mixing in the VCSEL diodes 10021, 10022, 10023. This photocurrent is detectable by the TIA connected to the second bias node 1096. As mentioned above, this arrangement allows addressability of the individual emitters formed by the individual back-emitting VCSEL diodes 10021, 10022, 10023 integrated with the individual RCPDs 10121, 10122, 10123 disposed thereon.

[0115] 11A-11B show a cross-sectional view and corresponding schematic diagram of an operating circuit of a second exemplary optoelectronic sensing device 1100 having multiple sets of back-emitting VCSEL diodes (similar to the VCSEL diode 302 described with respect to FIG. 3) integrated with an RCPD (similar to the RCPD 312 described with respect to FIG. 3) positioned away from the primary emission path of the VCSEL diodes. The optoelectronic sensing device 1100 has a first arrangement of electrical connections between the multiple sets, as described below.

[0116] As shown in FIG. 11A, the optoelectronic sensing device 1100 includes forming an injection layer 1109 on a surface 1108f of a substrate 1108, and then forming a first set of mesas 11101, 11102, 11103, and a second set of mesas 11104, 11106, and 11108. a , 1110 b , 1110 c 11A , each set of mesas may include more or fewer mesas forming a respective number of emitters. Each of the mesas 11101, 11102, 11103 includes an individual backside-emitting VCSEL diode 11021, 11022, 11023 integrated with an individual RCPD 11121, 11122, 11123 disposed thereon. An individual lattice structure 11201, 11202, 11203 is disposed on each of the individual RCPDs 11121, 11122, 11123. Each of the mesas 11101, 11102, 11103 forms a respective emitter #1, emitter #2, emitter #3, whereby respective primary radiation 11401, 11402, 11403 is emitted by respective back-emitting VCSEL diodes 11021, 11022, 11023 through respective on-chip lenses 11301, 11302, 11303 disposed on the rear surface 1108r of the substrate 1108.

[0117] Each of the respective VCSEL diodes 11021, 11022, 11023 may include a respective active region 11071, 11072, 11073 (similar to the active region 307 described with respect to FIG. 3) (not shown) which may include one or more quantum wells and may be adjacent to a respective oxide layer (not shown) having an opening through which the respective primary radiation 11401, 11402, 11403 escapes. The respective active regions 11071, 11072, 11073 may also include a respective gain stage layer 11041, 11042, 11043 (e.g., an InGaAs layer, an AlGaAs layer) (not shown) to improve the absorption efficiency of the respective primary radiation 11401, 11402, 11403. The individual RCPDs 11121, 11122, 11123 may include respective active regions 11141, 11142, 11143, which may also include one or more gain layers (e.g., InGaAs layers, AlGaAs layers) to improve the absorption efficiency of the respective altered primary radiation 11401, 11402, 11403 after undergoing self-mixing interference in the respective active regions 11071, 11072, 11073 of the respective VCSEL diodes 11021, 11022, 11023. One or more tunnel junctions and gain layers may be disposed between the respective active regions 11071, 11072, 11073 of the respective VCSEL diodes 11021, 11022, 11023 and the respective active regions 11141, 11142, 11143 of the RCPDs 11121, 11122, 11123.

[0118] When the individual VCSEL diodes 11021, 11022, 11023 are forward biased, the laser light of the individual primary emissions 11401, 11402, 11403 undergoes self-mixing interference within the individual active regions 11071, 11072, 11073 upon reflection or backscattering thereof. A corresponding one of the RCPDs 11121, 11122, 11123 receives the individual self-mixed primary emissions 11401, 11402, 11403 and detects the changed electrical properties of the individual self-mixed primary emissions 11401, 11402, 11403 upon reverse biasing.

[0119] In some embodiments, the first set of mesas 11101, 11102, 11103 and the second set of mesas 1110 a , 1110 b , 1110 c The second set of mesas 1110 may be formed by epitaxially growing a common set of semiconductor layers, forming trenches 1170, 1180 to define respective mesas, and then electrically connecting a selected number of the mesas to perform different functions or provide different routing structures. In the embodiment shown in FIG. 10A, the second set of mesas 1110 a , 1110 b , 1110 c Each one of the first set of mesas 11101, 11102, 11103 is adjacent to a respective one of the first set of mesas 11101, 11102, 11103 and is separated by a photodetector trench 1170 (formed, for example, by etching through a set of stacked semiconductor layers) that provides an electrical connection to a rear end of a respective one of the RCPDs 11121, 11122, 11123. a The adjacent mesas 11102, 11103 are separated by oxide trenches 1180 (also formed by etching through a set of stacked semiconductor layers) that provide electrical isolation between the respective active regions 11071, 11072, 11073 of the respective VCSEL diodes 11021, 11022, 11023. b A conductive layer 1160 (e.g., gold, copper) is applied over the individual lattice structures 11201, 11202, 11203 on each of the respective RCPDs 11121, 11122, 11123, and over the second set of mesas 1110. a , 1110 b , 1110 c , and provide electrical connections across the set of mesas.

[0120] The optoelectronic sensing device 1100 includes a common feed contact 1105 disposed on the injection layer 1109 and shared by each back-emitting VCSEL diode 11021, 11022, 11023 and each RCPD 11121, 11122, 11123 disposed thereon. As shown in FIG. 11A , a bias voltage applied via the common feed contact 1105 forward biases (current I LD At the same time, a reverse bias (current I PD 11161, 11162, 11163) serve to detect altered characteristics of the respective primary emissions 11401, 11402, 11403 due to self-mixing interference in the respective active regions 11071, 11072, 11073 of the individual VCSEL diodes 11021, 11022, 11023. One or more controllers, such as a processor 1204 described below with respect to FIG. 12, can be communicatively coupled to the optoelectronic sensing device 1100 to enable a configuration in which the individual VCSEL diodes 11021, 11022, 11023 are forward biased and the individual RCPDs 11121, 11122, 11123 are reverse biased.

[0121] The particular arrangement of electrical connections within the optoelectronic sensing device 1100 with the conductive layer 1160 allows for individual addressability of each emitter formed by a respective one of the mesas 11101, 11102, 11103. As a result, any selection of one or more emitters, emitter #1, emitter #2, emitter #3, can be used as a sensor to detect distance, motion of a target object 1150 using self-mixing interference captured by individual backside emitting VCSEL diodes 11021, 11022, 11023 integrated with individual RCPDs 11121, 11122, 11123 disposed thereon.

[0122] 11B, each of the backside emitting VCSEL diodes 11021, 11022, 11023 may be forward biased (via a common feed contact 1105) between a first bias node 1192 and a common node 1194, while the individual RCPDs 11121, 11122, 11123 may be reverse biased between the first bias node 1192 and a second bias node 1196. The first bias node 1192 and the common node 1194 may have different positive voltages such that the individual VCSEL diodes 11021, 11022, 11023 are driven by cathode load currents that cause individual primary emissions 11401, 11402, 11403 to be emitted therefrom. The first bias node 1192 and the second bias node 1196 may also have different positive voltages, whereby the individual RCPDs 11121, 11122, 11123 are reverse biased such that a photocurrent is generated when the individual RCPDs 11121, 11122, 11123 receive the individual primary radiation 11401, 11402, 11403 that has changed characteristics due to self-mixing in the VCSEL diodes 11021, 11022, 11023. This photocurrent is detectable by the TIA connected to the second bias node 1196. As mentioned above, this arrangement allows addressability of the individual emitters formed by the individual back-emitting VCSEL diodes 11021, 11022, 11023 integrated with the individual RCPDs 11121, 11122, 11123 disposed thereon.

[0123] 12A-12B respectively show a cross-sectional view and a corresponding schematic diagram of an operating circuit of a second exemplary optoelectronic sensing device 1200 having a resonant cavity extending to the emission side of a back-emitting MJ-VCSEL diode and integrated with an RCPD as described herein. The second example of the optoelectronic sensing device 1200 shown in and described with reference to FIGS. 12A-12B may have improved performance. In particular, the optoelectronic sensing device 1200 may have a relatively more stable polarization and be more stable in the optical mode than other optoelectronic sensing devices. In some cases, the optoelectronic sensing device 1200 may have a relatively higher signal strength for the RCPD output signal compared to other optoelectronic sensing devices.

[0124] The extended resonant cavity of the optoelectronic sensing device 1200 extends from the RCPD to the OCL 1230 formed on the rear surface 1208r of the substrate 1208 and includes the substrate 1208. In particular, Figure 12A shows a back-emitting MJ-VCSEL diode 1202 integrated with an RCPD 1212 positioned in the path of the primary emission 1240 of laser light from the MJ-VCSEL diode 1202 under forward bias. The RCPD 1212 receives the modified primary emission 1240 from the MJ-VCSEL diode 1202 after the primary emission 1240 undergoes self-mixing interference upon receiving reflection or backscattering therein.

[0125] The optoelectronic sensing device 1200 is fabricated by first forming a substrate 1208 (e.g., a low-loss semiconductor or dielectric material) with an extended cavity, forming an RCPD 1212 on a surface 1208f of the substrate, and then depositing a set of stacked semiconductor layers on the RCPD 1212 to form an MJ-VCSEL diode 1202 with a multi-junction structure. As described above, the extended resonant cavity significantly reduces the laser linewidth and extends the laser coherence length required for long-distance sensing. The OCL 1230 is disposed on a rear surface 1208r of the substrate 1208 and configured to collimate the laser light emitted by the VCSEL diode 1202 and collect the return laser light returning from the target object toward the VCSEL diode 1202 and a first active region in the RCPD 1212. A reflective coating 1235 made of a dielectric material may be disposed on the OCL 1230. In another example, a dielectric (multi-layer) DBR can be placed on the OCL 1230 to form a mirror for an extended resonant cavity.

[0126] In some examples, the OCL 1230 may be formed by etching the substrate 1208, resulting in a curved mirror. For example, the OCL 1230 may be formed using grayscale lithography, or the OCL 1230 may be formed using a reflowed photoresist. In other examples, the OCL 1230 may be formed from a dielectric material by a reflow process. In some examples, the OCL 1230 may be a dielectric material or an organic material.

[0127] In some examples, a reflective coating may be deposited on the OCL 1230 to form a mirror for the extended cavity of the optoelectronic sensing device 1200. In other examples, a dielectric (multi-layer) DBR structure may be deposited on the OCL 1230 to form a mirror for the extended cavity of the optoelectronic sensing device 1200.

[0128] The optoelectronic sensing device 1200 may include an emission-side (or "top") DBR layer 1203a that includes a set of pairs of alternating materials (e.g., AlGaAs, GaAs) with different refractive indices. In addition, the MJ-VCSEL diode 1202 may also include a base-side DBR layer 1203b that also includes a set of Bragg pairs of alternating materials (e.g., AlAs, GaAs) with different refractive indices. One or more of the materials of the emission-side DBR layer 1203a and the base-side DBR layer 1203b may be doped p-type and n-type, respectively, and thus form part of the anode and cathode portions of a pn diode structure, respectively.

[0129] The MJ-VCSEL diode 1202 may have multiple active regions 1207a, 1207b, 1207c (e.g., multiple pairs of barrier layers alternating with quantum well layers) that generate laser light when stimulated by a forward bias voltage. The multiple active regions 1207a, 1207b, 1207c may be interspersed with heavily doped tunnel junctions 1210a and 1210b (similar to the tunnel junction 310 described above with respect to FIG. 3) to form a vertically stacked multi-junction structure in the MJ-VCSEL diode 1202. One or more gain layers 1211a, 1211b (similar to the gain layer 311 described above with respect to FIG. 3) may be coupled to the tunnel junctions 1210a, 1210b, respectively, in the multi-junction structure in the MJ-VCSEL diode 1202. It should be noted that while in the embodiment shown in FIG. 12A there are three active regions 1207a-1207c interspersed with two tunnel junctions 1210a, 1210b coupled to a respective one of the two gain layers 1203a, 1203b, in other embodiments the MJ-VCSEL diode 1202 may have two or more than three of each type of layer forming a vertical stack between the DBR layers 1211a and 1211b.

[0130] Generally, in MJ-VCSEL diodes having different numbers of active regions, there is a tunnel junction between each successive pair of active regions. As shown in FIG. 12A, in MJ-VCSEL diode 1202, there is a first tunnel junction 1210a between active regions 1207a and 1207b, and a second tunnel junction 1210b between active regions 1207b and 1207c. Optionally, MJ-VCSEL diode 902 can also include one or more tunnel junctions (not shown) at locations other than between successive pairs of active regions 1207a-1207c. The tunnel junctions 1210a, 1210b of MJ-VCSEL diode 1202 can be of the same type or different types. Semiconductor materials that can be used for the tunnel junction layer include GaAs, Al x Ga 1-x As, In x Ga 1-x As, In x Ga 1-x P, GaAs 1-x N x 、In x Ga 1-x As y P 1-y 、and others known to those skilled in the art. Depending on the polarity of the junction, the tunnel junctions 1210a, 1210b help improve carrier injection / extraction from MJ-VCSEL diode 1202 to RCPD 1212 and reduce the operating voltage of optoelectronic sensing device 1200.

[0131] Each of active regions 1207a-1207c includes a plurality of barrier layers and quantum well layers. Materials that can be used for the barrier layers of active regions 1207a-1207c include Al x Ga 1-x As(0 < x ≤ 1), GaAs 1-x P x (0 < x ≤ 1), and others known to those skilled in the art. Materials that can be used for the quantum wells of active regions 1207a-1207c include In x Ga 1-x As(0 < x ≤ 1), In x Ga 1-x As y N 1-y, (0 < x ≤ 1, 0 < y ≤ 1), In x Ga 1-x As 1-y-z N y Sb z (0 < x ≤ 1, 0 < y < 1, 0 < z < 1, y + z < 1), and others known to those skilled in the art.

[0132] The MJ-VCSEL diode 1202 includes a radiation side (or "upper") oxide layer 1209a disposed adjacent to the uppermost active region 1207a or on the upper surface of the MJ-VCSEL diode 1202, and a base side (or "bottom") oxide layer 1209c disposed adjacent to the lowermost active region 1207c or on the bottom surface of the MJ-VCSEL diode 1202. The oxide layer 1209c includes an opening (or openings) through which the primary radiation 1240 escapes. The MJ-VCSEL diode 1202 can also include an additional oxide layer 1209b adjacent to the active region 1207b. Each of the oxide layers 1209a and 1209b includes an opening (or openings) that allows the primary radiation 1240 to pass between the active regions 1207a - 1207c. Other embodiments of the MJ-VCSEL diode may not have an oxide layer between consecutive active regions, or may have two or more. The openings in the oxide layers 1209a - 1209c allow the laser light generated within the active regions 1207a - 1207c to pass through each other, and can enhance the generation of the primary radiation 1240 of the laser light radiated through the optoelectronic sensing device 1200.

[0133] In some embodiments as shown in FIG. 12A, each of the active regions 1207a, 1207b, 1207c further includes one or more gain layers 1204a, 1204b, 1204c (e.g., InGaAs layer, AlGaAs layer) formed in the resonant cavity of the MJ-VCSEL diode 1202 to improve the efficiency of reabsorption of the primary radiation 1240 into the MJ-VCSEL diode 1202.

[0134] The emitter-side DBR layer 1203a and then the RCPD 1212 may be formed by epitaxial growth of layers on the substrate 1208, including the surface 1208f of the substrate 1208. The MJ-VCSEL diode 1202 may then be formed by epitaxial growth on the RCPD 1212. The base-side DBR layer 1203b may be formed by epitaxial growth on the MJ-VCSEL diode 1202.

[0135] In some embodiments, the RCPD 1212 may include an active region 1214 that may include one or more gain layers (e.g., InGaAs layers, AlGaAs layers) to improve the absorption efficiency of the altered primary radiation 1240 after undergoing self-mixing interference in the active regions 1207a-1207c of the VCSEL diode 902.

[0136] The MJ-VCSEL diode 1202 may have a common feed contact 1205a (shared with the RCPD 1212) disposed on or adjacent to the RCPD 1212, a first feed contact 1205b disposed on or adjacent to the emission-side DBR layer 1203a, and a second feed contact 1215a disposed on or adjacent to the base-side DBR layer 1203b. The common feed contact 1205a, the first feed contact 1205b, and the second feed contact 1215a may form a ring or horseshoe connection around the base-side DBR layer 1203b, the emission-side DBR layer 903a, and the RCPD 912, respectively.

[0137] When a bias voltage is applied, the laser diode current I LD 1216 is the applied laser diode voltage V LD As a result, current I may flow through the VCSEL diode 1202 between the common feed contact 1205a and the second feed contact 1215a, generating primary radiation 1240. This generates primary radiation 1240 that is directed through the substrate 1208 and the OCL 1230 towards a target object (not shown). At the same time, current I PD1206 is the applied photodiode voltage V PD 21 , may be communicatively coupled to the optoelectronic sensing device 1200. As a result, current flows through the RCPD 1212 between the common feed contact 1205a and the first feed contact 1205b of the RCPD 1212, thereby generating a reverse bias through the RCPD 1212. To enable configuration for forward biasing the VCSEL diode 1202 and reverse biasing the RCPD 1212, one or more controllers, such as a processor 2104, described below with respect to FIG.

[0138] When the VCSEL diode 1202 is forward biased, the laser light of the primary radiation 1240 undergoes self-mixing interference within the laser cavity of the active regions 1207a-1207c upon reflection or backscattering thereof. The RCPD 1212 receives the self-mixed primary radiation 1240 and detects the changed electrical properties of the primary radiation 1240 upon reverse biasing.

[0139] The MJ-VCSEL diode 1202 can emit laser light having characteristics different from those emitted by a single-junction VCSEL (SJ-VCSEL) diode 302 (shown in FIG. 3) operating at a similar current level. The MJ-VCSEL diode 1202 can operate at an increased voltage level (compared to the SJ-VCSEL diode 302 operating at a similar current level), which can provide multiple factors of increased gain in output power, for example. Also, the center frequency of the emitted laser light can be increased, which can improve the SNR because 1 / f noise is reduced. The increased SNR and higher operating frequency can also enable improved spatial resolution of a target by the optoelectronic sensing device 1200 with the MJ VCSEL diode 1202 due to the increased efficiency and tunability range for wavelength modulation of the emitted laser light by the MJ VCSEL diode 1202, which in turn enables better measurement of electrical parameters related to the self-mixing interference of the emitted laser light. Thus, the multi-junction structure in the MJ-VCSEL diode 1202 improves the performance of the optoelectronic sensing device 1200 through faster signal propagation, wider sampling, and reduced complexity.

[0140] In FIG. 12B, the VCSEL diode 1202 may be forward biased between the first bias node 1292 and the common node 1294, and the RCPD 1212 may be reverse biased between the common node 1294 and the second bias node 1296. By way of example, the first bias node 1292 may be driven to a positive voltage, the common node 1294 may be driven to a lower positive voltage (e.g., ground), and the second bias node 1296 may also be driven with a positive voltage. In different embodiments, different voltage levels may be used for the first bias node 2392, the common node 1294, and the second bias node 1296. Forward biasing the VCSEL diode 902 may drive a cathode load current that causes primary radiation 940a-c to radiate from the multi-junction structure 1201 having active regions 1207a-c interspersed with tunnel junctions 1210a-c. By reverse biasing the RCPD 1212, a photocurrent can be generated when the RCPD 1212 receives primary radiation 1240a-1240c whose characteristics have been altered due to self-mixing in the VCSEL diode 1202. This photocurrent can be detected by a TIA or another readout circuit connected to the second bias node 1296. As mentioned above, the multi-junction structure 1201 of FIG. 12A increases the thermal resistance as well as the tunability of the wavelength modulation for better measurement of the self-mixing interference.

[0141] Figure 13A shows a perspective view of a first exemplary set of optoelectronic sensing devices, such as the set of optoelectronic sensing devices shown and described with reference to Figures 9A-9B or 12A-12B. Figure 13A shows a schematic example of a set of optoelectronic sensing devices 1320 (a bank of optoelectronic sensing devices) sharing a common photodiode bank contact and a common bank contact, with each optoelectronic sensing device having an individual (e.g., addressable) power contact for the VCSEL diode.

[0142] The first exemplary set of optoelectronic sensing devices shows eight instances of optoelectronic sensing devices 1320 arranged in two rows and four columns. Each optoelectronic sensing device 1320 may be an instance of an optoelectronic sensing device 1200.

[0143] Each optoelectronic sensing device 1320 has an associated feed contact 1316. The feed contact 1316 is a conductive material (e.g., a p-contact) electronically coupled to a first bias node of the VCSEL of the optoelectronic sensing device 1320. In some examples, the feed contact 1316 is an example of the first bias node 1292 and / or the second feed contact 1215a.

[0144] A set of optoelectronic sensing devices share a common contact 1312 for the bank. The common contact 1312 is a conductive material that is electronically coupled to both a node of the VCSEL and a node of the RCPD, for example, as described in more detail with reference to Figures 9A-9B or 12A-12B. In some examples, the common contact 1312 is an example of the common node 1294 and / or the common power contact 1205a.

[0145] A set of optoelectronic sensing devices share a common photodiode contact 1314 for the bank. The common photodiode contact 1314 is a conductive material (e.g., an n-contact) that is electronically coupled to a node of the RCPD, for example, as described in more detail herein with reference to Figures 9A-9B or 12A-12B. In some examples, the common photodiode contact 1314 is an example of the second bias node 1296 and / or the first power supply contact 1205b.

[0146] The common contact 1312, the common photodiode contact 1314, and the power supply contact 1316 are configured and oriented to be accessible for contact with a conductor to provide an electrical signal between the contacts of another device to which the optoelectronic sensing device may be bonded. As described further herein, the first side of the set of optoelectronic sensing devices is the light emitting side of the device, the first side being opposite the common contact 1312, the common photodiode contact 1314, and the power supply contact 1316. In some implementations, this arrangement of contacts can provide contacts from drivers for the optoelectronic sensing devices, etc., to a two-dimensional set of addressable dots. Thus, in some cases, wire bonds and pads outside the array can be reduced or eliminated. Additionally, the number of emitters per array can be increased and large arrays of emitters can be utilized.

[0147] Figure 13B shows a cross-sectional view through section A of Figure 13A. The layers of the optoelectronic sensing device 1320 are generally electrically coupled with a common contact 1312, a common photodiode contact 1314, and a power supply contact 1316, as shown. The common contact 1312 may form a ring around a central portion of the optoelectronic sensing device 1320.

[0148] Figure 14 shows a top view of an exemplary sensing array 1400 including a set of optoelectronic sensing devices 1410. Figure 14 shows a schematic of an exemplary die architecture including an array of optoelectronic sensing devices, where each set (or bank) of optoelectronic sensing devices shares a common contact and a common photodiode contact.

[0149] The set of optoelectronic sensing devices 1410 may be one example of the set of optoelectronic sensing devices shown and described with reference to Figures 13A-13B. The common contact 1412, common photodiode contact 1414, and power supply contact 1416 associated with the optoelectronic sensing device 1420 may be examples of the common contact 1312, common photodiode contact 1314, and power supply contact 1316 associated with the optoelectronic sensing device 1420. The optoelectronic sensing device 1410 may be part of a larger bank 1402 of optoelectronic sensing devices.

[0150] In some examples, the sensing array 1400 may be a single die. The sensing array 1400 includes 28 of 32 banks 1402 of optoelectronic sensing devices arranged in a set of 14 rows 1404 and two columns, including a first column 1406 and a second column 1408. Each bank 1402 (a bank of optoelectronic sensing devices) shares a common contact 1412 and a common photodiode contact 1414, and each optoelectronic sensing device 1420 has an individual (e.g., addressable) power contact 1416 for the VCSEL diode.

[0151] As further described above, the contacts of the sensing array 1400 are on the surface opposite the light emitting surface of the device and are configured and oriented to be accessible for contact with another device, such as a driver. Each optoelectronic sensing device 1420 may have a width 1422 and a length 1424, including the area of ​​the optoelectronic sensing device 1420. Because a bank of optoelectronic sensing devices 1420 may share one of the common contacts 1412 and one of the common photodiode contacts 1414, the area of ​​the bank 1402 may be reduced relative to other optoelectronic sensing device architectures. For example, an architecture for a sensing array with a comparable number of optoelectronic sensing devices, where the contacts are routed around the periphery of the die, may result in an area larger than that of the sensing array 1400. Similarly, an architecture for a sensing array with a comparable number of optoelectronic sensing devices, where each optoelectronic sensing device is provided with three contacts, may also result in an area larger than that of the sensing array 1400.

[0152] Figure 15A illustrates a perspective view of a second exemplary set of optoelectronic sensing devices, such as the set of optoelectronic sensing devices shown and described with reference to Figures 9A-9B or 12A-12B. Figure 15A generally illustrates an example in which each optoelectronic sensing device 1520 has an isolated photodiode. That is, each photodiode can be addressed and read out separately, as opposed to a bank of photodiodes being collectively read out, e.g., as shown and described with reference to Figures 13A-14. Additionally, each optoelectronic sensing device 1520 has an individual (e.g., addressable) power contact for the VCSEL diode.

[0153] The first exemplary set of optoelectronic sensing devices shows six examples of optoelectronic sensing devices 1520 arranged in two rows and three columns. Each optoelectronic sensing device 1520 may be an example of an optoelectronic sensing device 1200. In some examples, each optoelectronic sensing device 1520 may be separated from adjacent optoelectronic sensing devices 1520 by a trench structure (e.g., an isolation trench). Each optoelectronic sensing device 1520 may be an example of an optoelectronic sensing device 1200.

[0154] Each optoelectronic sensing device 1520 has an associated feed contact 1516. The feed contact 1516 is a conductive material (e.g., a p-contact) electronically coupled to a first bias node of the VCSEL of the optoelectronic sensing device 1520. In some examples, the feed contact 1516 is an example of the first bias node 1292 and / or the second feed contact 1215a.

[0155] Each optoelectronic sensing device 1520 also has an associated common contact 1512. The common contact 1512 is a conductive material that is electronically coupled to both a node of the VCSEL and a node of the RCPD, e.g., as described in more detail with reference to Figures 9A-9B or 12A-12B. In some examples, the common contact 1512 is an example of the common node 1294 and / or the common power contact 1205a.

[0156] Each optoelectronic sensing device 1520 also has an associated photodiode contact 1514. The photodiode contact 1514 is a conductive material (e.g., an n-contact) that is electronically coupled to a node of the RCPD, as described in more detail with reference to Figures 9A-9B or 12A-12B. In some examples, the photodiode contact 1514 is an example of the second bias node 1296 and / or the first power contact 1205b.

[0157] The common contact 1512, the photodiode contact 1514, and the power supply contact 1516 are configured and oriented to be accessible for contact with a conductor to provide an electrical signal between the contacts of another device to which the optoelectronic sensing device may be bonded. As described further herein, a first side of the set of optoelectronic sensing devices is the light emitting side of the device, the first side being opposite the common contact 1512, the photodiode contact 1514, and the power supply contact 1516. In some implementations, this arrangement of contacts can provide contacts from drivers for the optoelectronic sensing devices, etc., to a two-dimensional set of addressable dots. Thus, in some cases, wire bonds and pads outside the array can be reduced or eliminated. Additionally, the number of emitters per array can be increased and large arrays of emitters can be utilized.

[0158] Figure 15B shows a cross-sectional view through section B of Figure 15A. The layers of the optoelectronic sensing device 1520 are generally electrically coupled with a common contact 1512, a common photodiode contact 1514, and a power supply contact 1516 as shown. The common contact 1512 may form a ring around a central portion of the optoelectronic sensing device 1520.

[0159] Figure 16 shows a top view of an example sensing array 1600 of optoelectronic sensing devices as shown and described with reference to Figures 15A-15B. Figure 15A generally depicts an example die architecture including an array of optoelectronic sensing devices, where the three contacts of each optoelectronic sensing device are individually accessible.

[0160] The optoelectronic sensing device 1620 may be an example of the optoelectronic sensing device 1520 shown and described with reference to Figures 15A-15B. The common contact 1612, the common photodiode contact 1614, and the power supply contact 1616 associated with the optoelectronic sensing device 1620 may be examples of the common contact 1512, the common photodiode contact 1514, and the power supply contact 1516 associated with the optoelectronic sensing device 1620. The optoelectronic sensing device 1620 may be part of a larger sensing array 1600.

[0161] In some examples, the sensing array 1600 may be a single die. The sensing array 1300 includes 30 optoelectronic sensing devices arranged in a set of five rows 1601 and six columns 1606. Each optoelectronic sensing device has individual (e.g., addressable) contacts including a common contact 1612, a common photodiode contact 1614, and a power supply contact 1616.

[0162] As further described above, the contacts of the sensing array 1600 are on the surface opposite the light emitting surface of the device and are configured and oriented to be accessible for contact with another device, such as a driver. Each optoelectronic sensing device 1620 may have a width 1622 and a length 1624, including the area of ​​the optoelectronic sensing device 1620. Because the optoelectronic sensing devices 1420 may be directly accessed from a bonded device (e.g., a driver chip), the area of ​​the sensing array 1600 may be reduced relative to other optoelectronic sensing device architectures. For example, an architecture for a sensing array with a comparable number of optoelectronic sensing devices, where the contacts are routed around the periphery of the die, may result in an area larger than that of the sensing array 1600.

[0163] 17 is a top view of a first exemplary layout 1700 of an optoelectronic sensing device, e.g., an optoelectronic sensing device, as shown and described with reference to FIGS. 9A-9B or 12A-12B. The optoelectronic sensing device 1710 may be an example of one of the optoelectronic sensing devices shown and described with reference to FIGS. 9A-9B, 12A-12B, 15A-16. FIG. 17 generally illustrates an exemplary layout of an example optoelectronic sensing device in which a common contact 1712 and a photodiode contact 1714 each form a ring around a central portion of the optoelectronic sensing device 1710. The optoelectronic sensing device 1710 may have an area defined by a length 1722 and a width 1724.

[0164] The common contact 1712, photodiode contact 1714, and power supply contact 1716 associated with optoelectronic sensing device 1710 may be examples of the common contact, common photodiode contact, and power supply contact associated with another optoelectronic sensing device described herein, such as the common contact 1512, common photodiode contact 1514, and power supply contact 1516 associated with optoelectronic sensing device 1520. Optoelectronic sensing device 1520 may be formed as part of a larger sensing array, such as sensing array 1600.

[0165] The common contact 1712 may generally form a first ring around the power supply contact 1716 for the optoelectronic sensing devices 1710. A portion of the common contact 1712 may extend away from the power supply contact 1716 and may be exposed such that the common contact may contact a conductor to form an electrical connection (e.g., to a chip driver bonded to the array of optoelectronic sensing devices 1710). The unexposed portion of the common contact 1712 (e.g., including the ring portion closest to the power supply contact 1716) may be covered with a dielectric to protect the contact and prevent shorting.

[0166] Similarly, the photodiode contacts 1714 may generally form a second ring around the first ring of the common contact 1712 and the feed contact 1716 of the optoelectronic sensing device 1710. A portion of the photodiode contacts 1714 may extend away from the feed contact 1716 and may be exposed for the common contact to contact a conductor to form an electrical connection. The unexposed portions of the photodiode contacts 1714 (e.g., including the ring portions closest to the common contact 1712 and the first ring for the feed contact 1716) may be covered with a dielectric to protect the contacts and prevent shorting.

[0167] 18 is a top view of a second exemplary layout 1800 of an optoelectronic sensing device, such as the optoelectronic sensing device shown and described with reference to FIGS. 9A-9B or 12A-12B. FIG. 18 illustrates a schematic of an exemplary layout of an example optoelectronic sensing device in which a common contact 1712 forms a first half of a ring around a central portion of the optoelectronic sensing device 1810 and a photodiode contact 1714 forms a second half of a ring around a central portion of the optoelectronic sensing device 1810. In some examples, the first half of the ring and the second half of the ring may be in the same plane. In other examples, at least a portion of the first half of the ring may be in a different plane than at least a portion of the second half of the ring.

[0168] The common contact 1712, photodiode contact 1714, and power supply contact 1716 associated with optoelectronic sensing device 1810 may be examples of the common contact, common photodiode contact, and power supply contact associated with other optoelectronic sensing devices described herein. Optoelectronic sensing device 1820 may be formed as part of a larger sensing array.

[0169] The common contact 1712 may generally form a first half of a ring around the feed contact 1716 for the optoelectronic sensing device 1810. A portion of the common contact 1712 may extend away from the feed contact 1716 and may be exposed so that the common contact may contact a conductor to form an electrical connection. The unexposed portion of the common contact 1712 (e.g., including the first half of the ring portion closest to the feed contact 1716) may be covered with a dielectric to protect the contact and prevent shorting.

[0170] Similarly, the photodiode contact 1714 may generally form a second half of a ring around the feed contact 1716 for the optoelectronic sensing device 1810. A portion of the photodiode contact 1714 may extend away from the feed contact 1716 and may be exposed for the common contact to contact a conductor to form an electrical connection. The unexposed portion of the photodiode contact 1714 (e.g., including the second half of the ring portion closest to the feed contact 1716) may be covered with a dielectric to protect the contact and prevent shorting.

[0171] The optoelectronic sensing device 1810 may have an area defined by a length 1822 and a width 1824. One or both of the length 1822 or width 1824 of the optoelectronic sensing device 1810 may be less than the length 1722 or width 1724 of the optoelectronic sensing device 1710 of an otherwise similar or equivalent optoelectronic sensing device. In general, a single split ring structure as shown and described with reference to the optoelectronic sensing device 1810 may have a relatively smaller area (and, e.g., a relatively higher density) than a two ring structure as shown and described with reference to the optoelectronic sensing device 1710.

[0172] Although the second exemplary layout 1800 shows a first half of a ring for the common contact 1712 and a second half of a ring for the photodiode contact 1714, the rings may be divided according to different ratios. For example, the contact area to the optoelectronic sensing device 1810 may be adjusted by changing the relative contact area, such as between the common contact 1712 and the photodiode contact 1714, via a larger or smaller amount of half a ring for one or the other of the contacts.

[0173] Figure 19 is a top view of a first array 1900 of the second exemplary layout of optoelectronic sensing devices shown and described with reference to Figure 18. Figure 19 depicts a generally square or rectangular pattern (e.g., a grid or array) of optoelectronic sensing devices 1810, where a unit area is according to a width 1922 and a length 1924. The optoelectronic sensing devices 1810 may be as shown and described with reference to the second exemplary layout 1800.

[0174] Figure 20 is a top view of a second array 2000 of the second exemplary layout of optoelectronic sensing devices shown and described with reference to Figure 18. Figure 20 generally illustrates a hexagonal pattern (e.g., grid or array) of optoelectronic sensing devices including optoelectronic sensing device 2010 and optoelectronic sensing device 2020, where a unit area is according to width 2022 and length 2024.

[0175] The optoelectronic sensing device 2010 and the optoelectronic sensing device 2020 may be similar to the optoelectronic sensing device 1810 in the second exemplary layout 1800, but may also be different. In particular, the optoelectronic sensing device 2010 may include the same central portion and a split ring around the central portion, including a first half of the ring portion closest to the feed contact 1716 and a second half of the ring portion closest to the feed contact 1716. However, the portion of the common contact 1712 that extends away from the feed contact 1716 and the portion of the photodiode contact 1714 that extends away from the feed contact 1716 may be in a different position relative to the optoelectronic sensing device 2010. In particular, these portions may be configured to generally enable a hexagonal pattern of the second array 2000. In some examples, the layout of the optoelectronic sensing device 2010 is the same as the layout of the optoelectronic sensing device 2020, but rotated 180 degrees. In other examples, the locations of the common contact 1712 and the photodiode contact 1714 of the optoelectronic sensing device 2010 may be different (eg, swapped) than in the optoelectronic sensing device 2020.

[0176] In some examples, the unit area (due to width 2022 and length 2024) of the optoelectronic sensing device 2010 may be smaller than the unit area (due to width 1922 and length 1924) of the optoelectronic sensing device 1810. Thus, in some examples, the second array 2000 of optoelectronic sensing devices may be smaller (e.g., higher density, smaller pitch) than the first array 1900 of optoelectronic sensing devices for the same number of devices.

[0177] 21 illustrates an example electrical block diagram of an electronic device 2100 having an optoelectronic sensor, such as the optoelectronic sensing device described with reference to FIG. 3. The electronic device 2100 may take the form of a handheld or portable device (e.g., a smartphone, a tablet computer, or an electronic watch), a vehicle navigation system, or the like. The electronic device 2100 may include an optional display 2102 (e.g., a light-emitting display), a processor 2104, a power source 2106, a memory 2108 or storage device, a sensor system 2110, or optional input / output (I / O) mechanisms 2112 (e.g., input / output devices and / or input / output ports). The processor 2104 may control some or all of the operation of the electronic device 2100. The processor 2104 may communicate, directly or indirectly, with substantially all components of the electronic device 2100. For example, a system bus or other communication mechanism 2114 may provide communication between the processor 2104 , the power supply 2106 , the memory 2108 , the sensor system 2110 , and the input / output mechanism 2112 .

[0178] The processor 2104 may be embodied as any electronic device capable of processing, receiving, or transmitting data or instructions. For example, the processor 2104 may be a microprocessor, a central processing unit (CPU), an application specific integrated circuit (ASIC), a digital signal processor (DSP), or a combination of such devices. The term "processor" as used herein is intended to encompass a single processor or processing unit, multiple processors, multiple processing units, or any other suitably configured one or more computing elements.

[0179] It should be noted that in some embodiments, components of electronic device 2100 may be controlled by multiple processors, for example, select components of electronic device 2100 may be controlled by a first processor and other components of electronic device 2100 may be controlled by a second processor, where the first and second processors may or may not be in communication with each other.

[0180] The power source 2106 may be implemented by any device capable of providing energy to the electronic device 2100. For example, the power source 2106 may comprise one or more disposable or rechargeable batteries. Additionally or alternatively, the power source 2106 may comprise a power connector or power cord that connects the electronic device 2100 to another power source, such as a wall outlet.

[0181] The memory 2108 can store electronic data that can be used by the electronic device 2100. For example, the memory 2108 may store electronic data or content, such as audio and video files, documents and applications, device settings and user preferences, timing signals, control signals, data structures or databases, image data, maps, or focus settings, etc. The memory 2108 can be configured as any type of memory. By way of example only, the memory 2108 may be implemented as random access memory, read-only memory, flash memory, removable memory, other types of storage elements, or a combination of such devices.

[0182] The electronic device 2100 may also include one or more optoelectronic sensors that define a sensor system 2110. The sensors may be located virtually anywhere on the electronic device 2100. The sensor(s) may be configured to sense virtually any type of characteristic, such as, but not limited to, touch, force, pressure, electromagnetic radiation (e.g., light), heat, motion, relative motion, biometric data, distance, etc. For example, the sensor system 2110 may include touch sensors, force sensors, thermal sensors, position sensors, light or optical sensors, accelerometers, pressure sensors (e.g., pressure transducers), gyroscopes, magnetometers, health monitoring sensors, image sensors, etc. Additionally, the one or more sensors may utilize any suitable sensing technology, including, but not limited to, capacitive, ultrasonic, resistive, optical, ultrasonic, piezoelectric, and thermal sensing technologies.

[0183] The I / O mechanism 2112 may transmit and / or receive data from a user or another electronic device. The I / O device may include a touch-sensitive input surface such as a display, a trackpad, one or more buttons (e.g., a graphical user interface "home" button or one of the buttons described herein), one or more cameras (including one or more image sensors), one or more microphones or speakers, one or more ports such as a microphone port, and / or a keyboard. Additionally or alternatively, the I / O device or port may transmit electronic signals over a communication network, such as a wireless and / or wired network connection. Examples of wireless and wired network connections include, but are not limited to, a cellular connection, a Wi-Fi® connection, a Bluetooth® connection, an IR connection, and an Ethernet connection. The I / O mechanism 2112 may also provide feedback (e.g., a haptic output) to the user.

[0184] The foregoing description, for convenience of explanation, uses specific terminology to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art upon reading this description that specific details are not required to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one skilled in the art upon reading this description that many modifications and variations are possible in light of the above teachings.

[0185] While the disclosed embodiments have been shown and described with respect to one or more implementations, equivalent alterations and modifications will occur or become known to those skilled in the art upon reading and understanding this specification and the accompanying drawings. Moreover, while particular features of the invention may be disclosed with respect to only one of several implementations, such features may be combined with one or more other features of other implementations, as may be desirable and advantageous for any given or particular application.

[0186] Although various embodiments of the present disclosure have been described above, it should be understood that the embodiments have been presented as merely examples and are not limiting. Many modifications to the disclosed embodiments can be made in accordance with the disclosure herein without departing from the spirit or scope of the present disclosure. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described embodiments. Rather, the scope of the present disclosure should be defined in accordance with the following claims and their equivalents.

Claims

1. 1. An optoelectronic sensing device, comprising: a vertical cavity surface emitting laser (VCSEL) diode defined at least in part by a first set of semiconductor layers disposed on a substrate, the first set of semiconductor layers including a first active region; a resonant cavity photodetector (RCPD) defined at least in part by a second set of semiconductor layers vertically adjacent to the VCSEL diode and disposed on the substrate, the second set of semiconductor layers including a second active region; a tunnel junction disposed between the first active region of the first set of semiconductor layers and the second active region of the second set of semiconductor layers; the VCSEL diode is configured to emit laser light toward the substrate upon application of a first bias voltage, and to undergo self-mixing interference upon receiving reflection or backscattering of the emitted laser light; The RCPD is configured to detect the self-mixing interference during emission of the laser light by the VCSEL diode upon application of a second bias voltage.

2. The optoelectronic sensing device of claim 1 , wherein the VCSEL diode is disposed between the substrate and the RCPD.

3. The optoelectronic sensing device of claim 1 , wherein the RCPD is disposed between the substrate and the VCSEL diode.

4. a first power contact disposed on or adjacent to one or more of the second set of semiconductor layers; a second power contact disposed on or adjacent to one or more of the first set of semiconductor layers; 4. The optoelectronic sensing device of claim 3, further comprising: a common supply contact disposed on or adjacent a layer between the first active region of the first set of semiconductor layers and the second active region of the second set of semiconductor layers.

5. 5. The optoelectronic sensing device of claim 4, wherein the optoelectronic sensing device is a first optoelectronic sensing device of a bank of an array of a plurality of optoelectronic sensing devices, each optoelectronic sensing device of the plurality of optoelectronic sensing devices sharing a common photodiode bank contact coupled to the second feed contact and sharing a common bank contact for the VCSEL diodes coupled to the common feed contact.

6. 5. The optoelectronic sensing device of claim 4, wherein the optoelectronic sensing device is a first optoelectronic sensing device of an array of a plurality of optoelectronic sensing devices, each optoelectronic sensing device of the plurality of optoelectronic sensing devices having a photodiode contact coupled to the second feed contact and a common contact for the VCSEL diode coupled to the common feed contact.

7. 13. The optoelectronic sensing device of claim 1, further comprising a controller configured to switch bias polarity of the RCPD to capture multiple detections of the self-mixing interference in the time domain for time-multiplexed sample readout.

8. 1. An optoelectronic sensing device, comprising: a substrate having a front surface and a back surface; A set of stacked semiconductor layers disposed on the surface, a vertical cavity surface emitting laser (VCSEL) diode having a first active region within a resonant cavity, the VCSEL diode configured to emit primary radiation through the backside surface towards the substrate upon application of a first bias voltage; a resonant cavity photodetector (RCPD) having a second active region offset from the first active region; a lattice structure disposed on the set of laminated semiconductor layers; An optoelectronic sensing device comprising:

9. the VCSEL diode is forward biased during the primary emission; light emitted by the VCSEL diode during the primary emission undergoes self-mixing interference within the resonant cavity of the VCSEL diode upon receiving a reflection or backscattering of the primary emission; The optoelectronic sensing device of claim 8 , wherein the RCPD is configured to detect the self-mixing interference upon application of a second bias voltage during the primary emission by the VCSEL diode.

10. The optoelectronic sensing device of claim 8 , wherein the grating structure is disposed vertically on the RCPD.

11. 9. The optoelectronic sensing device of claim 8, wherein the VCSEL diode further comprises a multijunction stack within the resonant cavity of the VCSEL diode, the multijunction stack comprising one or more gain stage layers interconnected with one or more vertically stacked tunnel junction layers.

12. 12. The optoelectronic sensing device of claim 11 , wherein the VCSEL diode further comprises one or more oxide layers formed on a top surface of the VCSEL diode, on a bottom surface of the VCSEL diode, or within the multi-junction stack, each of the one or more oxide layers defining one or more oxide openings.

13. 12. The optoelectronic sensing device of claim 11 , wherein the substrate defines at least a portion of an extended laser cavity separated from the multi-junction stack of the VCSEL diode by a set of distributed Bragg reflector (DBR) layers formed on the substrate.

14. 10. The optoelectronic sensing device of claim 8, wherein the RCPD comprises one or more gain stage layers disposed within a resonant cavity of the RCPD, the one or more gain stage layers comprising indium gallium arsenide.

15. an on-chip lens disposed on the back surface of the substrate; 10. The optoelectronic sensing device of claim 8, further comprising: a reflective coating disposed on the on-chip lens and configured to reflect a portion of the primary radiation back towards the first active region.

16. The optoelectronic sensing device of claim 8 , wherein the grating structure is filled with a dielectric material comprising one of silicon oxide, aluminum oxide, and silicon nitride.

17. 1. An optoelectronic sensing device, comprising: a substrate having a front surface and a back surface; A set of laminated semiconductor layers disposed on the surface, a first set of one or more mesas, each mesa in the first set of one or more mesas comprising: a vertical cavity surface emitting laser (VCSEL) diode having a first active region within a resonant cavity of the VCSEL diode, the VCSEL diode configured to emit primary radiation through the backside surface towards the substrate upon application of a first bias voltage; a first set of one or more mesas including a first active region offset from the first active region and a resonant cavity photodetector (RCPD) configured to detect self-mixing interference of the primary radiation within a laser cavity of the VCSEL diode upon receiving reflection or backscatter upon application of a second bias voltage; a set of stacked semiconductor layers defining a set of mesas, including a second set of one or more mesas; at least one electrical conductor electrically connected to an element of a first mesa in the first set of one or more mesas and routed onto a portion of a second mesa in the second set of one or more mesas; An optoelectronic sensing device comprising:

18. 20. The optoelectronic sensing device of claim 17, wherein at least two adjacent mesas are operatively separated by a trench etched through the set of laminated semiconductor layers, and a conductor of the at least one conductor is disposed within the trench.

19. 20. The optoelectronic sensing device of claim 18, wherein the trench extends through the set of laminated semiconductor layers into the substrate.

20. 20. The optoelectronic sensing device of claim 17, wherein the at least one electrical conductor enables RCPDs in the first set of one or more mesas to be individually addressed.

Images