阅读说明：本技术 可调谐液晶超表面 (Tunable liquid crystal super surface ) 是由 格列布·M·阿克塞尔罗德 杨元穆 帕特里克·博文 于 2020-03-13 设计创作，主要内容包括：可调谐的光学超表面可以包括光学反射表面以反射光学辐射,例如红外激光。光学谐振天线的阵列可以例如以例如小于波长一半的亚波长间隔从反射表面延伸或以其他方式定位在该反射表面上。压控液晶可以定位在每个光谐振天线的光场区域中。控制器可以向光学谐振天线的液晶施加电压差偏置模式,该光学谐振天线可以排列成平铺、交错或随机排列的光学谐振天线的子集,以获得一维波束控制、二维波束控制和/或空间光束成形。(The tunable optical super-surface may include an optically reflective surface to reflect optical radiation, such as infrared laser light. An array of optically resonant antennas may extend from or otherwise be positioned on a reflective surface, e.g., at sub-wavelength intervals of less than half a wavelength. The voltage controlled liquid crystal may be positioned in the optical field area of each optically resonant antenna. The controller may apply a voltage difference bias pattern to the liquid crystals of the optically resonant antennas, which may be arranged into a subset of tiled, staggered, or randomly arranged optically resonant antennas to achieve one-dimensional beam steering, two-dimensional beam steering, and/or spatial beam shaping.)

1. A solid state light detection and ranging (LiDAR) transceiver system, comprising:

a first tunable optically reflective super-surface that reflects optical radiation emitted within an operating bandwidth,

wherein the first optically reflective meta-surface comprises a first array of optically resonant antennas arranged at sub-wavelength intervals on a first reflective surface in a subset of N optically resonant antennas, where N is an integer, and

liquid crystals are positioned in a light field region of the optical resonant antennas in the first array;

a light source that emits light radiation within the operational bandwidth to the first optically reflective super-surface;

a voltage controller that selectively applies a voltage difference bias pattern of N difference biases to the liquid crystals of each subset piece of the N optically resonant antennas in the first array of optically resonant antennas to harmonically steer the emitted optical radiation to a target location;

a second optically reflective super-surface tunable by the voltage controller to receive optical radiation bouncing off the target location,

wherein the second optically reflective meta-surface comprises a second array of optically resonant antennas arranged on the second reflective surface at sub-wavelength intervals, an

Liquid crystals are positioned in the optical field area of the optically resonant antennas in the second array; and

a sensor that receives optical radiation from the second optically reflective super-surface.

2. The transceiver system of claim 1 wherein the light source comprises a diode laser.

3. The transceiver system of claim 1 wherein the sensor comprises an array of Avalanche Photodiodes (APDs).

4. The transceiver system of claim 1, wherein the sensor comprises an array of Single Photon Avalanche Diodes (SPADs).

5. The transceiver system of claim 1 wherein the voltage controller is tunable to steer emitted optical radiation to a target location by modifying a phase of reflected optical radiation associated with each of the optically resonant antennas of the first array.

6. The transceiver system of claim 1 wherein the optically resonant antennas of each of the first and second arrays comprise metal tracks extending from the respective first and second reflective surfaces, wherein the metal tracks are spaced apart from each other to form a channel therebetween.

7. The transceiver system of claim 1, wherein the first and second reflective surfaces comprise portions of a single reflective layer located below the optically resonant antenna.

8. A tunable optical metasurface comprising:

a light-reflecting surface that reflects optical radiation within an operating bandwidth;

an array of optically resonant antennas divided into a plurality of subsets of optically resonant antennas, wherein the optically resonant antennas are positioned on the optically reflective surface with intra-antenna spacing less than half a wavelength within the operating bandwidth;

a liquid crystal positioned in an optical field area of each of the optically resonant antennas; and

a voltage controller that selectively applies a voltage difference bias pattern to the liquid crystals in the optical field region of each respective subset of optically resonant antennas via a plurality of unique control inputs,

wherein at least some of the optically resonant antennas in different subsets of optically resonant antennas share a common control input such that the number of unique control inputs is less than the total number of optically resonant antennas in the array of optically resonant antennas.

9. The super-surface of claim 8, wherein the voltage controller is configured to:

applying a first bias to the liquid crystal in the optical field region of at least a first optically resonant antenna of each respective subset of optically resonant antennas, an

Applying a second voltage bias to the liquid crystals in the optical field region of at least a second optically resonant antenna of each respective subset of optically resonant antennas.

10. The super-surface of claim 8, wherein the array of optically resonant antennas comprises a plurality of metal tracks extending from the optically reflective surface, wherein the metal tracks are spaced apart from one another to form channels therebetween.

11. The super-surface of claim 10, wherein each metal track is in electrical communication with the voltage controller.

12. The super-surface of claim 10, wherein the liquid crystal fills spaces between each metal track.

13. A super-surface as claimed in claim 10, wherein each metal track comprises a copper metal track.

14. The super-surface of claim 10, wherein each metal track comprises an aluminum metal track.

15. The super-surface of claim 10, wherein the optically reflective surface comprises a copper surface, and wherein a dielectric separates each metal track from the copper surface.

16. The super-surface of claim 10, wherein each of the plurality of subsets of optically resonant antennas comprises approximately 1,000 metal tracks.

17. A meta-surface as claimed in claim 10, wherein each of the metal tracks extends between opposite edges of the optically reflective surface.

18. A tunable optical metasurface comprising:

a light-reflecting surface that reflects optical radiation within an operating bandwidth;

an array of optically resonant copper tracks extending from the reflective surface, the array being subdivided into a plurality of subsets of copper tracks,

wherein each subset of copper tracks comprises N copper tracks, where N is an integer,

wherein each copper track is spaced from an adjacent copper track by less than half a wavelength within the operating bandwidth,

wherein each copper track is electrically insulated from the reflective surface;

liquid crystal positioned in the optical field area between adjacent copper tracks; and

a voltage controller that selectively applies a pattern of N voltage differences between adjacent copper tracks to the copper tracks of each subset of copper tracks to generate a corresponding reflected phase pattern for selective beam forming.

19. The super-surface of claim 18, wherein N is between 100 and 10,000.

20. The super-surface of claim 18, wherein each copper track is insulated by a layer of dielectric material covering the copper surface.

21. A tunable optical metasurface comprising:

a light-reflecting surface that reflects optical radiation within an operating bandwidth;

an array of optically resonant antennas positioned on the light reflective surface at an intra-antenna spacing of less than half a wavelength within the operating bandwidth;

a liquid crystal positioned in a light field region of each of the optical resonance antennas; and

a voltage controller that selectively:

applying a voltage difference bias pattern to the liquid crystals in the light field region of the first subset of optically resonant antennas, an

Applying the same voltage difference bias pattern to the liquid crystals in the light field region of the second subset of the optically resonant antennas.

22. A tunable optical metasurface comprising:

a light-reflecting surface that reflects optical radiation within an operating bandwidth;

an array of optically resonant copper tracks extending from the reflective surface,

wherein each copper track is spaced from an adjacent copper track by less than half a wavelength within the operating bandwidth, an

Wherein each copper track is electrically insulated from the reflective surface;

liquid crystal positioned in the light field region between adjacent copper tracks;

a voltage controller that selects and applies a repeating pattern of voltage differences between adjacent copper tracks to generate corresponding reflected phase patterns for selective beam shaping.

23. A tunable optical metasurface comprising:

a light-reflecting surface that reflects optical radiation within an operating bandwidth;

an array of optically resonant antennas positioned on the optically reflective surface at an intra-antenna pitch that is less than half a wavelength within the operating bandwidth,

wherein the array of optically resonant antennas comprises a plurality of copper metal tracks extending from the optically reflective surface, wherein the metal tracks comprise one of copper, aluminum, gold, and silver, wherein the metal tracks are spaced apart from one another to form channels therebetween;

a liquid crystal positioned in a light field region of each of the optical resonator antennas; and

a voltage controller that selectively:

applying a voltage difference bias pattern to the liquid crystals in the light field region of the first subset of optically resonant antennas, an

Applying the same voltage difference bias pattern to the liquid crystals in the light field region of the second subset of the optically resonant antennas.

24. The super-surface of claim 23, wherein the optically reflective surface comprises a copper surface, and wherein a dielectric separates each metal track from the copper surface.

25. The super-surface of claim 23, wherein the voltage controller is configured to apply a same voltage bias to the liquid crystals in the light field region of each of a plurality of subsets of optically resonant antennas, the subsets including the first subset and the second subset.

Technical Field

The present disclosure relates to optical resonators and antennas. In particular, the present disclosure relates to tunable metasurfaces.

Drawings

FIG. 1A shows a diagram of a tunable optical meta-surface, according to one embodiment.

FIG. 1B shows optical radiation incident on the super-surface of FIG. 1A at an angle of incidence.

Fig. 1C shows an applied voltage difference bias pattern that steers the reflected optical radiation at a first steering angle.

Fig. 1D shows the optical radiation reflected at a first steering angle, shown as less than 90 degrees with respect to the incident angle.

FIG. 2A illustrates an example of a solid-state LiDAR system according to one embodiment.

FIG. 2B illustrates the transmitting and receiving super surfaces of the solid state LiDAR system of FIG. 2A with one-dimensional beam steering.

FIG. 2C illustrates a top view of an exemplary light path of a solid state LiDAR system.

FIG. 2D illustrates a side view of the light path of a solid state LiDAR system according to one embodiment.

FIG. 3 shows an example of an optically reflective surface having liquid crystal covered metal tracks extending therefrom, according to one embodiment.

FIG. 4A shows an optically reflective copper surface covered with an insulating layer and metal tracks extending therefrom with liquid crystal therebetween, according to one embodiment.

Fig. 4B shows an optically reflective copper surface covered with an insulating layer and extending therefrom metal tracks with a liquid crystal layer applied therein according to yet another embodiment.

Fig. 4C illustrates an optical field area associated with adjacent metal tracks extending from an optically reflective copper surface, according to one embodiment.

Fig. 5 shows a voltage controlled refractive index and a corresponding reflection phase of a liquid crystal according to an embodiment.

Fig. 6 shows a simulation of beam steering reflection of optical radiation at a reflection angle of minus 10 degrees according to an embodiment.

Fig. 7A shows a first voltage pattern applied to a one-dimensional array of metal tracks to produce a reflected beam at a first steering angle, according to one embodiment.

Fig. 7B shows a second voltage pattern applied to the one-dimensional array of metal tracks to produce a reflected beam at a second steering angle, according to one embodiment.

Fig. 7C shows a third voltage pattern applied to the one-dimensional array of metal tracks to produce a reflected beam at a third steering angle, according to one embodiment.

Fig. 7D illustrates a fourth voltage pattern applied to the one-dimensional array of metal tracks to produce a reflected beam at a fourth steering angle, according to one embodiment.

Fig. 8 shows a block diagram of an array of optically resonant antenna tracks subdivided into track subsets each comprising X tracks with X corresponding voltage bond pads, according to one embodiment.

Fig. 9 shows an example of a packaged array of optically resonant antennas that can be tuned via the perimeter of the voltage contacts, according to one embodiment.

FIG. 10 illustrates an exemplary one-dimensional scan via a solid-state LiDAR system, according to various embodiments.

Detailed Description

The tunable optical metasurfaces can be used for beam shaping, including three-dimensional beam shaping, two-dimensional beam steering, or one-dimensional beam steering. In various embodiments, the tunable optical meta-surface may include an optically reflective surface. The optically reflective surface may be a metal surface selected to reflect optical radiation within a particular bandwidth. A large number of optically resonant antennas can be positioned on the reflective surface. The optically resonant antenna may have sub-wavelength characteristics and be arranged at sub-wavelength intervals. For example, the individual optically resonant antennas and the spacing therebetween may be less than half a wavelength.

The liquid crystal may be positioned around the optically resonant antenna, as a layer on top of the optically resonant antenna, and/or as part of the optically resonant antenna. A digital or analog controller may selectively apply varying voltage differences across the liquid crystal within the optical field area of each optically resonant antenna. The voltage controller may apply a voltage difference bias pattern, such as a blazed grating pattern, to the meta-surface to obtain a target beam steering angle.

A one-dimensional voltage bias pattern can be applied to the liquid crystals within the optical field region of the optically resonant one-dimensional antenna array to achieve one-dimensional beam steering. A two-dimensional voltage bias pattern may be applied to the liquid crystals within the optical field region of the two-dimensional array of optically resonant antennas to achieve two-dimensional beam steering and/or spatial beam shaping. One-dimensional beam steering, two-dimensional beam steering, and spatial beam shaping are generally encompassed herein by the term "beam shaping".

The super-surface may have a default reflection angle or reflection mode based on the reflective properties of the optically reflective surface, the unpolarized resonant antenna, and the unpolarized liquid crystal. In various embodiments, biasing the liquid crystal changes a phase of reflection of optical radiation proximate to the associated optically resonant antenna. Each different voltage pattern on the super-surface corresponds to a different reflected phase pattern. For a one-dimensional array of optically resonant antennas, each different reflected phase pattern corresponds to a different steering angle in a single dimension. For a two-dimensional array of optically resonant antennas, each different reflected phase pattern may correspond to a different two-dimensional beam steering angle. Alternatively, each different reflection mode may be used to achieve a unique spatial beam form.

A variety of shapes, sizes, materials, configurations, etc. may be utilized. For example, the optically resonant antenna may be formed as a metal track extending from an optically reflective surface. In some embodiments, the deposits of liquid crystal may fill a portion of each channel between adjacent optically resonant antennas. In other embodiments, the liquid crystal may be formed as a layer on top of the optically resonant antenna filling the channels therebetween.

The voltage controller may apply a voltage pattern to the metal tracks to bias the liquid crystals associated therewith to obtain a target reflective phase pattern. In embodiments where the optically reflective surface is metallic and the optically resonant antenna is metallic, a dielectric or another insulator may separate the metallic surface and the optically resonant antenna. The voltage controller may be connected to the metal tracks via contacts around the super-surface or via insulated vias in the metal surface.

Copper is an example of a metal that is suitable for use with the infrared bandwidth typically used for light detection and ranging or LiDAR (e.g., 905 nanometer LiDAR systems and 1550 nanometer LiDAR systems) and is cost effective. Copper is also useful at various other operating wavelengths, and alternative metals (e.g., gold, silver, aluminum, etc.) and various dielectrics and metal-coated dielectrics are known to be highly reflective at various wavelengths. It should be understood that some materials may be preferred for visible wavelengths, other materials may be more suitable for ultraviolet wavelengths, and still other materials may be more suitable for infrared wavelengths, as is known in the art.

One specific example of a tunable optical super-surface is a planar copper reflector covered with silicon dioxide. 10,000 to 100,000 copper tracks extend from the silicon dioxide coated copper reflector. The copper tracks are subdivided into subsets of copper tracks. Each subset of copper tracks comprises 100 to 10,000 copper tracks. The tunable optical meta-surface may include a number of electrical contacts equal to the number of copper tracks in each subset.

For example, each subset may include 1,000 tracks, and the tunable optical meta-surface may include 50 subsets of a total of 50,000 metal tracks. The tunable optical meta-surface may include 1,000 electrical contacts. Each electrical contact may be connected to one track in each subset.

The liquid crystal deposited between the metal tracks may be fixed via an optically transparent cover (e.g. glass). Applying a voltage pattern to the 1,000 electrical contacts via the voltage controller results in a voltage difference bias pattern applied to the liquid crystal that changes its local reflection phase. The beam steering controller selects a voltage pattern corresponding to a reflected phase pattern of the target beam steering angle. By modifying the applied voltage, the incident light radiation can be turned in one direction. Similar embodiments using posts or pillars instead of elongated metal rails may be used to allow two-dimensional beam steering or spatial beam shaping.

Various combinations of the above-described embodiments and features may be used to construct a solid state light detection and ranging (LiDAR) transmitter, receiver, or transceiver system. According to various embodiments, a transceiver system may include a first tunable optically reflective super-surface for transmitting light and a second tunable optically reflective super-surface for receiving light reflected by distant objects (bounce light). The distance to distant objects can be calculated by measuring the time of flight of the transmitted and bounced light. Each optically reflective super-surface comprises an optically reflective surface (or reflective layered surface) with an array (e.g., a two-dimensional or one-dimensional array) of sub-wavelength optically resonant antennas. A voltage bias pattern applied to the liquid crystal associated with the optically resonant antenna modifies its local reflection phase. The controller can selectively apply the voltage pattern to achieve a target beam steering angle or beam form.

LiDAR systems may utilize laser diode light sources for transmission, such as laser diodes that emit optical radiation at a standard wavelength of 905 nanometers or 1550 nanometers. Various other wavelengths may be used with the systems and methods described herein, including visible wavelengths, sub-infrared wavelengths, and infrared wavelengths. The LiDAR system may include a receiver to reflect reflected optical radiation from a target steering angle or beam shape (e.g., corresponding to a transmitted steering angle or beam shape) to a receiving sensor (e.g., an avalanche photodiode array).

It should be appreciated that the super-surface techniques described herein may incorporate or otherwise take advantage of previous advancements in surface scattering antennas, such as those described in U.S. patent publication No. 2012/0194399, which is incorporated herein by reference in its entirety. Additional elements, applications and features of surface scattering antennas characterized by a reference wave or feed wave are described in U.S. patent publication nos. 2014/0266946, 2015/0318618, 2015/0318620, 2015/0380828, 2015/0162658 and 2015/0372389, each of which is incorporated herein by reference in its entirety. Specific descriptions of optically resonant antenna configurations and feature sizes are described in U.S. patent applications 15/900,676, 15,900,683, and 15/924,744 (each of which is incorporated herein by reference in its entirety).

In the present disclosure, examples of transmit (or receive) embodiments are provided, with the understanding that mutual receive (or transmit) embodiments are also contemplated. Similarly, it should be understood that the system may operate as a transmitter only, as a receiver only, as both a transmitter and a receiver, with time division multiplexing of the transmitter/receiver, and/or with the first super-surface acting as a transmitter and the second super-surface acting as a receiver.

Many previous advances in surface scattering antennas have focused on relatively low frequencies (e.g., microwave and radio frequency bands). The presently described embodiments support optical bandwidth and are therefore suitable for use with LiDAR and other optical-based sensing systems. In particular, the systems and methods described herein operate in the sub-infrared, mid-infrared, high-infrared, and/or visible frequency ranges (generally referred to herein as "optical"). The described super-surface may be fabricated using micro-and/or nano-lithographic processes, such as the fabrication methods typically used to fabricate Complementary Metal Oxide Semiconductor (CMOS) integrated circuits, taking into account the required feature sizes for the sub-wavelength optically resonant antenna and the antenna pitch.

Some infrastructures that may be used with the embodiments disclosed herein are already available, such as general purpose computers, computer programming tools and techniques, digital storage media, and communication links. Many of the systems, subsystems, modules, components, etc. described herein can be implemented as hardware, firmware, and/or software. The various systems, subsystems, modules, and components are described in terms of the functions they perform, as there are a wide variety of possible implementations. For example, it will be appreciated that many existing programming languages, hardware devices, frequency bands, circuits, software platforms, network infrastructures, and/or data stores may be used alone or in combination to implement particular control functions.

It will also be appreciated that two or more of the elements, devices, systems, subsystems, components, modules, etc. described herein may be combined into a single element, device, system, subsystem, module or component. Further, many of the elements, devices, systems, subsystems, components, and modules may be duplicated or further divided into separate elements, devices, systems, subsystems, components, or modules to perform the subtasks of those described herein. Any embodiment described herein may be combined with any combination of the other embodiments described herein. Various permutations and combinations of the embodiments are contemplated to the extent they are not mutually inconsistent.

As used herein, a computing device, system, subsystem, module, or controller may include a processor, such as a microprocessor, microcontroller, logic circuit, or the like. The processor may comprise one or more special-purpose processing devices such as an Application Specific Integrated Circuit (ASIC), a Programmable Array Logic (PAL), a Programmable Logic Array (PLA), a Programmable Logic Device (PLD), a Field Programmable Gate Array (FPGA), or other customizable and/or programmable device. The computing device may also include a machine-readable storage device, such as non-volatile memory, static RAM, dynamic RAM, ROM, CD-ROM, magnetic disks, magnetic tape, magnetic, optical, flash, or other machine-readable storage medium. Aspects of certain embodiments may be implemented or enhanced using hardware, software, firmware, or combinations thereof.

The components of some disclosed embodiments are described and illustrated in the figures herein to provide specific examples. Many of its parts can be arranged and designed in a wide variety of different configurations. Furthermore, features, structures, or operations associated with one embodiment may be applied to, or combined with, features, structures, or operations described in connection with another embodiment. In many instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the disclosure. The right to add any described embodiments or features to any one figure and/or as a new figure is explicitly reserved.

The embodiments of the systems and methods provided in this disclosure are not intended to limit the scope of the disclosure, but are merely representative of possible embodiments. In addition, the steps of a method need not be performed in any particular order, even in sequence, nor need the steps be performed only once. As previously mentioned, the description and variations with respect to the transmitter are equally applicable to the receiver, and vice versa.

FIG. 1A shows a diagram of a tunable optical meta-surface 100, according to one embodiment. In the illustrated embodiment, the optical super-surface comprises optically resonant antennas 150 configured as elongated tracks arranged in a one-dimensional array. Block diagram 150' provides a conceptual diagram of an optically resonant antenna 150 as a resonator tuned to a particular optical frequency or range of optical frequencies. The elongated track may be connected to a programmable logic controller, CPU, microcontroller, or another controller to selectively apply a tuning signal to modify the resonance of optically resonant antenna 150. Each control pin 120 may allow a tuning signal to control the resonance of one or more optically resonant antennas, as described in detail in accordance with various embodiments herein.

FIG. 1B shows optical radiation 125 incident on the super-surface 100 of FIG. 1A at an angle of incidence. The angle of incidence shown is approximately 45 degrees. Incident optical radiation is shown as being incident on the conceptual block diagram 150', but it should be understood that optical radiation will actually be incident on the optically resonant antenna 150 of the super-surface 100. However, the tuning fork shown in conceptual diagram 150' provides a visualization of the function of the super surface 100.

Fig. 1C shows an applied voltage differential bias pattern 175 applied to the tuning fork of functional block diagram 150' to divert reflection of incident optical radiation 125 at a first divert angle. As shown, different voltage differences 175 can be applied to different tuning forks of conceptual diagram 150'. In various embodiments, each tuning fork can represent a plurality of adjacent or non-adjacent optically resonant antennas. As previously described, each unique voltage difference bias pattern 175 can correspond to a different radiation pattern (e.g., beam steering, beam shape, amplitude, phase delay, etc.).

Graph ID shows that light radiation 125 is reflected at an acute angle as "reflected light radiation" 126 (i.e., the turning angle is shown as less than 90 degrees relative to the incident angle). Modifying the voltage 175 applied to the optically resonant antenna 150 changes the voltage difference affecting the liquid crystal associated therewith. Each different voltage difference modifies the refractive index of the liquid crystal and corresponds to a different reflection phase. In a one-dimensional array of the elongate track type optically resonant antenna 150, as shown, each different mode of reflection phase results in a different beam steering angle.

FIG. 2A illustrates an example of a solid-state LiDAR system 200 according to one embodiment. The illustrated housing 205 is merely an example, and any number of alternative shapes, sizes, styles, etc. are possible. At least one window portion 250 of the housing 205 may be optically transparent at the operating wavelength. In some embodiments, the window portion 250 may be uncovered to allow all optical radiation to enter the housing 205. In still other embodiments, the window portion 250 may include a filter to filter some or all of the electromagnetic radiation (and optionally harmonics thereof) that is not within the operating bandwidth.

FIG. 2B illustrates the transmitting 210 and receiving 215 super surfaces of the solid state LiDAR system 200 of FIG. 2A with one-dimensional beam steering. Laser diode 206 (e.g., a 905 nm laser diode or a 1550 nm laser diode) illuminates the transmissive super-surface 210 via collimating/focusing optics 204 with optical radiation (not shown for clarity). Optical radiation incident on the transmissive super-surface is reflected from the transmissive super-surface as transmitted optical radiation 226. The control circuitry (e.g., microchip 235) tunes the optically resonant antenna of the transmissive meta-surface 210 by applying a voltage difference bias pattern to the liquid crystal associated therewith to select a reflected phase pattern corresponding to the target beam steering angle of the reflected optical radiation 226.

The control circuit 235 also tunes the optically resonant antenna of the receiving meta-surface 215 by applying a corresponding voltage differential bias pattern to select a reflection phase pattern corresponding to the same target beam steering angle. The transmitted optical radiation 226 bounces off of distant objects and is received by the receiving super-surface 215 as bounced optical radiation 227. The optical radiation 227 received by the receiving super-surface 215 is reflected by the super-surface at the target beam steering angle to the receiving sensor 207. The receiving super-surface 215 may reflect the optical radiation to the receiving sensor 207 through a spherical lens (not shown). The receiving sensor 207 may be an array of photodiodes, such as an array of Avalanche Photodiodes (APDs) or an array of Single Photon Avalanche Diodes (SPADs).

FIG. 2C illustrates a top view of an exemplary light path of the solid state LiDAR system 200 of FIGS. 2A and 2B. One or more light sources (e.g., an array of diodes 206 as shown) transmit optical radiation through collimating optics 204 to transmissive subsurface 210. In particular, optical radiation from the array of diodes 206 is collimated by the collimating optics 204 to the transmissive aperture region 211 on the transmissive super-surface 210.

The transmitted optical radiation bounces off of one or more distant objects and is received by the receiving super-surface 215 as bounced optical radiation. The optical radiation is reflected by the receiving aperture region 216 of the receiving super-surface 215 through the spherical lens 217 to be received by the receiving sensor 207. Fig. 2C also includes a graphical plot 201 of the field of the transmitted beam relative to the entire field of view (FOV) provided by the illustrated optical path.

FIG. 2D illustrates a side view of the light path of a solid state LiDAR system 200 according to one embodiment. As previously described, one or more diodes (e.g., laser diode 206) generate optical radiation 230 that passes through the collimating optics 204 as collimated optical radiation 228. The collimated light radiation is reflected by the transmissive meta-surface 210 as transmitted light radiation 226. The transmitted optical radiation bounces off one or more distant objects and returns as bounced optical radiation 227. The bouncing optical radiation 227 is reflected by the receiving super-surface 215 as reflected optical radiation 229 and refracted by the spherical lens 217. The refracted optical radiation 231 is received by the receiving sensor 207.

Fig. 3 shows an example of an optically reflective super-surface 300 with a reflective surface 301 (e.g. a metal reflector or a dielectric reflector). Reflective surface 301 has an insulating layer 305 to provide electrical insulation from metal track optically resonant antenna 375. Each optically resonant antenna 375 has an electrically insulating layer 380. Electrically insulating layer 380 may also cover the top of each metal track optically resonant antenna 375.

Fig. 4A shows a particular embodiment of a tunable optically resonant antenna 401 extending from an optically reflective surface 410. The copper antenna track 430 extends perpendicularly from the optically reflective surface 410, but is electrically insulated therefrom by a layer of oxide or other dielectric material 420. An insulating layer 440 (e.g., silicon nitride or another electrically insulating layer) covers each copper antenna track 430. Liquid crystal 450 is deposited in the gaps between adjacent copper antenna tracks 430. The voltage controller 460 applies a voltage to the copper antenna track 430. The reflection phase associated with the liquid crystal 450 may be tuned based on the voltage difference between the copper antenna tracks 430 generated by the voltage controller 460.

Figure 4B shows another example of a tunable optical resonant antenna 403 having exemplary dimensions according to one embodiment. The voltage controller 461 is in electrical contact with the copper antenna track 430 via the optically reflective surface 410 and insulating vias in the oxide layer 420. The liquid crystal layer 452 covers the insulator 440 on the copper antenna track 430 and fills the gaps therebetween. Insulator 440 may, for example, comprise silicon nitride, an oxide, or another electrical insulator.

Fig. 4C shows a light field area 480 associated with an adjacent metal track 430 extending from the oxide layer 420 on the optically reflective surface 410, according to one embodiment. The electric field applied by the voltage controller 460 tunes the optically resonant antenna 404 by modifying the refractive index of the liquid crystal applied on, around, or between the resonant metal tracks 430.

Fig. 5 shows a graph 500 of the voltage controlled refractive index and the corresponding reflection phase 510 of a liquid crystal 520 according to one embodiment. Graph 500 shows that the phase of reflection can vary significantly based on the refractive index 520 of the dielectric. As shown, phase modulation of approximately 2 pi radians (index modulation of only 0.25) is possible. Liquid crystals are suitable materials that provide a variable index of refraction 520 and a corresponding reflective phase 510 based on a variable control voltage difference.

FIG. 6 shows a simulation 600 of beam steering to a super-surface, where optical radiation is incident at-70 degrees and reflected at-10 degrees, both measured relative to the normal vector of the super-surface, according to one embodiment.

Fig. 7A shows a first voltage pattern 790 applied to a one-dimensional array of metal tracks 700. The laser 710 generates incident optical radiation 711 to illuminate a tunable metasurface having a one-dimensional array of metal tracks 700. A voltage pattern 790 of high and low voltages may be applied to tune the super-surface to reflect incident optical radiation 711 as a reflected beam 725 at a first steering angle of about-50 °.

Fig. 7B shows a second voltage pattern 791 applied to the one-dimensional array of metal tracks 700 to produce a reflected beam 726 at a second steering angle of about-30 °.

Fig. 7C shows a third voltage pattern 792 applied to the one-dimensional array of metal tracks 700 to produce a reflected beam 727 at a third steering angle of about 5 deg., in accordance with one embodiment.

Fig. 7D shows a fourth voltage pattern 793 applied to the one-dimensional array of metal tracks 700 to produce a reflected beam 728 at a fourth steering angle of approximately 40 deg., according to one embodiment.

In summary, fig. 7A to 7D show various voltage patterns applied to obtain various target steering angles. It should be understood that in each of the illustrated embodiments, the laser 710 may be replaced with a sensor array (e.g., APD or SPAD) to receive the bouncing optical radiation reflected at the target steering angle from the receiving super-surface of the metal track 700.

Fig. 8 shows a block diagram 800 of an array of optically resonant antenna tracks subdivided into a subset 830 of X tracks, the subset 830 having X corresponding voltage bond pads 805 on the chip. Routing bus 820 may route contacts 805 between voltage bond pads and an array of metal track subsets 830. For example, 50,000 copper tracks may be subdivided into 50 subsets 830 of every 1,000 copper tracks. The tunable optical meta-surface may include a number of electrical contacts 805 equal to the number of copper tracks in each subset 830. Each electrical contact may be connected to one track within each subset 830. Thus, the reflected phase pattern of each subset of copper tracks 830 may be the same as the reflected phase pattern of every other subset of copper tracks 830.

The block diagram 800 of the tunable optical meta-surface may be used for spatial beam shaping, two-dimensional beam steering, or one-dimensional beam steering, depending on the configuration of the tracks and the applied voltage pattern. For example, a one-dimensional array of elongated tracks may be used for one-dimensional beam steering. A two-dimensional array of struts or a plurality of one-dimensional arrays of elongate tracks arranged in a two-dimensional array may be used for two-dimensional beam steering and/or spatial beam shaping.

As in the previous embodiments, the subset of optical tracks may extend from an optically reflective surface (e.g., copper). The liquid crystal may be positioned between the tracks, as a covering on each individual track, within the gaps between adjacent tracks, or as a layer covering the tracks and the gaps therebetween. A variety of shapes, sizes, materials, configurations, etc. may be utilized.

Fig. 9 shows an example of a packaged chip 900 having an array of perimeter tunable optically resonant antennas via electrical contacts 932, according to an embodiment. Incident optical radiation 925 from the laser diode is reflected as transmitted optical radiation 926 at a target steering angle based on a voltage (e.g., a voltage or galvanic electrical contact) applied via electrical contacts 932.

FIG. 10 illustrates an exemplary one-dimensional scan through a solid-state LiDAR system 1000, according to various embodiments. As shown, the solid state LiDAR system 1000 may implement a one-dimensional scan along a horizontal field of view with a fixed vertical field of view. The transmissive meta-surface transmits light radiation 1026 at a first horizontal angle (e.g., 120 as shown) at a fixed vertical viewing angle (e.g., 25 as shown). The transmitted optical radiation 1026 bounces off distant objects, represented by plane 1050, although it is recognized that distant objects may be at different distances from the solid-state LiDAR system 1000 and not necessarily in the same plane.

Remote objects bounce the optical radiation back into bouncing optical radiation 1027. The receiving super surface receives the solid state LiDAR system 1000 at respective horizontal angles and vertical fields of view. In various embodiments, and as described herein, a solid state LiDAR system may be scanned at various scan angles along a horizontal field of view by modifying the reflection phase pattern of the transmitting and receiving super-surfaces over a scan period.

In other embodiments, a LiDAR system can include a tunable transmissive metasurface for transmitting beam-shaped optical radiation according to any of the embodiments described herein. However, instead of using a tunable metasurface to receive the bounced optical radiation, the LiDAR system may include a fixed-focus receiver, a receiver with limited tuning capability, and/or one or more omnidirectional receivers. In other embodiments, the LiDAR system may include a tunable receiving super-surface according to any of the embodiments described herein, but include more conventional emitters, such as fixed focus emitters, limited focus emitters, or omni-directional emitters.

In still other embodiments, the system may function only as a transmitter and include a tunable metasurface for transmitting optical radiation, but without a corresponding receiver. Similarly, the system may function only as a receiver and include a tunable metasurface for receiving optical radiation, but without a corresponding transmitter.

In any of the various embodiments, the optically resonant antenna may be formed as an elongated metal track for one-dimensional beam steering, as shown and described. In other embodiments, columns and rows of posts may be used for two-dimensional beam shaping and/or spatial beam shaping. In an embodiment for one-dimensional beam steering, each optically resonant antenna can include a first elongated metal track extending from an insulator having a defined width W and length L to a height H. The proportion of metal tracks can be selected for a particular resonance within the operating wavelength. The elongated metal tracks may extend between edges of the underlying reflective surface and may be substantially parallel to each other.

Similarly, in any of the various embodiments, the optically resonant antenna can include a high-Q tunable resonant waveguide, such as a high-Q tunable resonant plasmonic waveguide. This high sensitivity to the dielectric index is achieved by a high Q value of the resonance (e.g. Q > -10). Any of a variety of mathematical models for beam steering may be used, including, for example, the Gerchberg-Saxton algorithm.

The disclosure has been made with reference to various exemplary embodiments, including the best mode. However, those skilled in the art will recognize that changes and modifications may be made to the exemplary embodiments without departing from the scope of the present disclosure. While the principles of the disclosure have been illustrated in various embodiments, many modifications of structure, arrangement, proportions, elements, materials, and components may be adapted to specific environments and/or operative requirements without departing from the principles and scope of the present disclosure. These and other variations and modifications are intended to be included within the scope of the present disclosure.

The present disclosure is to be considered as illustrative and not restrictive, and all such modifications are intended to be included within the scope thereof. Benefits, other advantages, and solutions to problems have been described above with regard to various embodiments. However, the benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element. Accordingly, it is intended that the present disclosure at least cover the following claims.