Photonic integrated circuits using random sparse optical phased arrays

Abstract

A photonic integrated circuit (PIC) is disclosed herein. The PIC may include a substrate and a main optical waveguide supported by the substrate. The main optical waveguide may be in communication with an electromagnetic radiation source and may be configured to receive electromagnetic radiation from the electromagnetic radiation source. A first branch optical waveguide may be optically coupled to the main optical waveguide at a first location. An optical phased array (OPA) may include a plurality of array elements, each of the plurality of array elements may include an optical antenna and an optical phase modulator. At least some of the array elements in a first subset of the plurality of array elements may be optically coupled to the first branch optical waveguide, and the locations of at least some of the plurality of array elements are non-periodic in one or more directions on the substrate.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 63 / 278,024, filed November 10, 2021, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Optical phased arrays (OPAs) may be used in photonic integrated circuits (PICs) to facilitate the transmission or reception of optical signal beams. Photonic integrated circuits may have multiple photonic or optical based functions integrated into the photonic integrated circuit. OPAs may be used to transmit optical signal beams by utilizing antenna elements to form the optical signal beam. The phase and / or amplitude associated with the optical signal beam transmitted from the antenna elements may be controlled or adjusted by one or more optical phase and / or amplitude modulators to perform beam shaping, beam pointing, and / or beam steering in one or more dimensions.

[0003] However, conventional OPAs cannot perform two-dimensional far-field beam steering when the number of antenna elements becomes too large due to challenges in optical and electrical routing (e.g., routing of waveguides and electrical wiring). In arrays such as these, the large number of antenna elements results in an inability to scale the circuit topology and interferes with the optical and electrical routing on the OPA due to the limited space available to allow for optical and electrical routing on the PIC. Increasing the distance between array elements to allow for more space for optical and electrical routing has the undesirable consequence of larger grating lobes from the optical signal beam or receive beam gain envelope, reducing the steering range of the optical signal beam. Thus, scalability of OPAs is often not possible without causing significant degradation to the optical signal.

[0004] Furthermore, large-scale OPAs that achieve two-dimensional beam steering do so by sweeping the wavelength of the source laser input to the OPA to steer the beam in one of two directions. For this reason, large-scale OPAs cannot function in applications that require a fixed laser wavelength or a laser wavelength with a finite tuning range. To alleviate the above problems, the field of photonic integrated circuits (PICs) requires alternative arrangements for the optical and electrical routing of OPAs that allow scalability and sidelobe suppression of OPAs. [Brief description of the drawings]

[0005] Features and advantages of the subject technology will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which together illustrate, by way of example, features of the subject technology.

[0006] [Figure 1] 1 illustrates a schematic diagram of a pair of optical transceiver nodes including an optical transmitter and / or an optical receiver, according to an example of the present disclosure. [Diagram 2] 1 illustrates an isometric view of an optical device housing an optical transmitter and / or an optical receiver according to an example of the present disclosure. [Diagram 3] 1 shows a perspective view of a photonic integrated circuit based optical device according to an example of the present disclosure. [Figure 4] FIG. 4 shows a perspective view of the interior of the photonic integrated circuit-based optical device of FIG. 3. [Diagram 5] 4 shows a partial exploded view of the photonic integrated circuit-based optical device of FIG. 3. [Figure 6] FIG. 4 shows a schematic diagram of an optical phased array (OPA) in a photonic integrated circuit. [Figure 7] FIG. 7 illustrates a top view of a portion of the optical phased array of FIG. 6 in accordance with an example of the present disclosure. [Figure 8] FIG. 8 illustrates a plan view of a portion of the optical phased array of FIG. [Figure 9] FIG. 9 illustrates a plan view of a portion of the optical phased array of FIG. [Figure 10]FIG. 1 shows a diagram of an optical signal beam emanating from an optical phased array of a photonic integrated circuit according to an example of the present disclosure. [Figure 11] 4 illustrates a graph of main lobe and side lobe intensity of an optical signal beam according to an example of the present disclosure. [Figure 12] 1 illustrates a simulation of a main lobe and side lobes of an optical signal beam emanating from an optical phased array, according to an example of the present disclosure. [Figure 13] 4 shows a perspective view of the photonic integrated circuit of FIG. 3. [Figure 14] FIG. 1 illustrates a plan view of waveguide routing on an optical phased array according to an example of the present disclosure. [Figure 15] FIG. 1 illustrates a plan view of waveguide routing on an optical phased array according to an example of the present disclosure. [Figure 16] 1 illustrates a method for constructing a photonic integrated circuit according to an example of the present disclosure.

[0007] Referring now to the illustrated examples, the specification uses specific language to describe the same, however, it should be understood that no limitation of scope is intended thereby. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An initial overview of the inventive concepts is provided below, followed by a more detailed description of specific examples. This initial overview is intended to aid the reader in understanding the examples more quickly, but is not intended to identify key features or essential features of the examples, nor is it intended to limit the scope of the claimed subject matter.

[0009] In view of the above, there is a need for a photonic integrated circuit using an optical phased array that can provide two-dimensional far-field beam steering by a large number of antenna elements. The photonic integrated circuit and optical phased array described herein can solve the above problems. The optical phased array (OPA) described herein has array elements (e.g., nanoantenna elements) that are separated by a distance greater than half the wavelength of the emitted electromagnetic radiation (i.e., optical energy) while still providing sufficient side lobe suppression. The OPA can also be scaled to a larger size to allow additional space for optical and electrical routing. The optical phased array further includes nanoantenna elements that are positioned in the array by a genetic algorithm to minimize side lobe interference of the optical signal beam (or receive gain envelope) emitted from the OPA at multiple scan angles of the optical signal beam. The OPA described herein is a large-scale OPA that achieves two-dimensional beam steering without sweeping the wavelength of the source laser input over multiple wavelengths. The OPA can receive electromagnetic radiation of a single coherent wavelength and steer the optical signal beam by phase modulation of the individual nanoantenna elements.

[0010] In one example of the present disclosure, a photonic integrated circuit (PIC) can include a substrate and a waveguide at least partially supported by the substrate. The waveguide can be in communication with at least one of an electromagnetic radiation source (optical energy source) and a receiver. The waveguide can be configured to facilitate the propagation of an optical signal beam. Additionally, the PIC can include an optical phased array (OPA) having a plurality of array elements, each of the plurality of array elements can include an optical antenna and an optical phase modulator associated with the optical antenna. The optical phase modulator is operable to modulate the optical signal beam in a segment of the waveguide in communication with the optical antenna. At least some of the array elements of the plurality of array elements can be optically coupled to the waveguide at non-periodic positions on the substrate.

[0011] In some examples, the optical phased array is a sparse array in which multiple array elements may be positioned such that the distance between the array elements is greater than one-half of a wavelength of electromagnetic radiation from the electromagnetic radiation source.

[0012] In some examples, the non-periodic positions of array elements in an optical phased array (OPA) can be set such that an emitted optical signal beam or a received gain envelope from multiple array elements has a peak-to-sidelobe ratio that is greater than a predetermined threshold. The peak-to-sidelobe ratio can be the ratio of the peak beam intensity to the grating lobe intensity in the emitted beam or received gain envelope.

[0013] In some examples, the non-periodic positions of array elements in an optical phased array (OPA) may be pseudo-random positions set such that an emitted optical signal beam or a receive gain envelope from a plurality of array elements has a peak-to-sidelobe ratio greater than a predetermined threshold at each of a plurality of scan angles of the emitted optical beam or receive gain envelope.

[0014] In some examples, the multiple scan angles of the emitted light beam or the received gain envelope can have angles between −60 degrees and +60 degrees.

[0015] In some examples, the pseudo-random positions of the array elements can be set such that the emitted optical signal beams or receive gain envelopes from the multiple array elements have a peak-to-sidelobe ratio greater than a predetermined threshold at each of multiple scan angles between −60 degrees and +60 degrees.

[0016] In some examples, the pseudo-random positions of the array elements can be set such that the emitted optical signal beam or the received gain envelope can be continuously steered over multiple scan angles by controlling the phase adjustments made by one or more of the optical phase modulators.

[0017] In some examples, the pseudo-random positions of the array elements can be set such that the emitted optical signal beam or received gain envelope from multiple array elements can be continuously steered over multiple scan angles using a single coherent wavelength of electromagnetic radiation provided by an electromagnetic radiation source by controlling phase adjustments provided by one or more of the optical phase modulators.

[0018] In some examples, the pseudo-random positions of the array elements can be set such that the emitted optical signal beam or received gain envelope from multiple array elements is steerable in two dimensions by controlling phase adjustments made by one or more of the optical phase modulators.

[0019] In some examples, the locations of at least some of the plurality of array elements may be non-periodic in one or more directions on the substrate.

[0020] In some examples, the photonic integrated circuit (PIC) may further include at least one of a source laser as an electromagnetic radiation source configured to generate optical energy, an antenna element configured to transmit an optical signal beam based on the optical energy, and a receiver configured to receive the optical signal beam by the antenna element and process the received optical signal beam.

[0021] In some examples, the source laser is capable of generating optical energy at a single coherent wavelength.

[0022] In some examples, the waveguide is an optical waveguide.

[0023] In some examples, on-chip electronics may be disposed on the substrate and in electrical communication with the optical phase and / or amplitude modulators of each of the plurality of array elements, and may be configured to apply a voltage to each of the optical phase and / or amplitude modulators to modulate an optical signal beam in a segment of the waveguide in communication with the optical antenna.

[0024] In some examples, the photonic integrated circuit (PIC) can include multiple layers. The multiple layers can include a photonic layer having an optical phased array (OPA) and a waveguide. The multiple layers can further include an electronic layer having a digital readout integrated circuit (DRIIC) in electrical communication with each of the optical phase and / or amplitude modulators of the array elements, which can be configured to apply voltages to control each of the optical phase and / or amplitude modulators.

[0025] In some examples, the electronic layer may include one or more CMOS circuits.

[0026] In another example of the present disclosure, the photonic integrated system can include an electromagnetic radiation source (i.e., an optical energy source). The system can further include a photonic integrated circuit (PIC). The photonic integrated circuit (PIC) can include a substrate and a waveguide at least partially supported by the substrate. The waveguide can be in communication with at least one of an electromagnetic radiation source and a receiver. The waveguide can be configured to facilitate propagation of an optical signal beam. The PIC can further include an optical phased array (OPA) having a plurality of array elements, each of the plurality of array elements can include an optical antenna and an optical phase and / or amplitude modulator associated with the optical antenna. The optical phase modulator is operable to modulate the optical signal beam in a segment of the waveguide in communication with the optical antenna. At least some of the array elements of the plurality of array elements can be optically coupled to the waveguide, and the location of at least some of the plurality of array elements can be non-periodic in one or more directions on the substrate.

[0027] In some examples of photonic integrated systems, the optical phased array can be a sparse array, where multiple array elements are positioned such that the distance between the array elements is greater than one-half of the wavelength of electromagnetic radiation from the electromagnetic radiation source.

[0028] In some examples of photonic integrated systems, the non-periodic positions of array elements in an optical phased array (OPA) can be set such that an emitted optical signal beam or a received gain envelope from multiple array elements has a peak-to-sidelobe ratio greater than a predetermined threshold. The peak-to-sidelobe ratio can be the ratio of peak beam intensity to grating lobe intensity in the emitted beam or received gain envelope.

[0029] In some examples of photonic integrated systems, the non-periodic positions of array elements in an optical phased array (OPA) may be pseudo-random positions set such that an emitted optical signal beam or a received gain envelope from a plurality of array elements has a peak-to-sidelobe ratio greater than a predetermined threshold at each of a plurality of scan angles of the emitted optical beam or the received gain envelope.

[0030] In another example of the present disclosure, a method can include configuring a photonic integrated circuit (PIC). The method can include configuring the photonic integrated circuit (PIC) to include a substrate. The method can further include configuring the photonic integrated circuit (PIC) to include a waveguide at least partially supported by the substrate, the waveguide in communication with at least one of an electromagnetic radiation source and a receiver, the waveguide can be configured to facilitate propagation of an optical signal beam. The method can further include configuring the photonic integrated circuit (PIC) to include an optical phased array (OPA) having a plurality of array elements. Each of the plurality of array elements can include an optical antenna and an optical phase and / or amplitude modulator associated with the optical antenna. The optical phase and / or amplitude modulator is operable to modulate the optical signal beam in a segment of the waveguide in communication with the optical antenna. The method can further include configuring at least some of the array elements of the plurality of array elements to be optically coupled to the waveguide, and the location of at least some of the plurality of array elements can be non-periodic in one or more directions on the substrate.

[0031] Optical Phased Arrays and Photonic Integrated Circuits Configurations 1 through 16 described below and the various examples used to illustrate the principles of the present disclosure are illustrative only and should not be construed as limiting the scope of the present disclosure in any way. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any type of suitably arranged device or system.

[0032] As described above, the transmitting OPA uses antenna elements to form a transmit optical signal beam, and the phases associated with the antenna elements may be controlled or adjusted to perform beam shaping, beam pointing, or beam steering. The antenna elements and various other components of or associated with the OPA may be implemented using one or more PICs. The present disclosure provides a compact, scalable design that is provided to support a PIC-based communications optical signal beaming system. The design may be provided in a variety of configurations to support a variety of space, air, and ground-based systems.

[0033] The OPA may include a two-dimensional (2D) pseudorandom sparse array (RSA) of silicon nanoantenna elements or other antenna elements, whose relative phases may be electronically controlled to support fast non-mechanical beamforming and beam steering. The random sparse array (RSA) of antenna elements may also support features such as high sidelobe suppression of the transmit optical signal beam or receive gain envelope, fixed wavelength laser sources in transmit or receive, lasers with finite tunable wavelength ranges, sufficient space for optical and electronic routing, and scalability without inducing disturbances or degradation during operation of the OPA. In some cases, the array may support a unit cell architecture with low power resonant microrings or other modulators, so that each antenna element may be independently calibrated and controlled. If desired, a supercell design (logically grouping multiple antenna elements and associated components into multiple supercells) may be useful for simplifying routing and allowing size scalability. In some cases, amplitude modulation of each supercell, such as Taylor weighting and other techniques, may be used to control power transfer and shape the beam.

[0034] The principles described herein may have various advantages or benefits depending on the implementation. For example, the random and sparse optical phased array described herein allows efficient electrical and optical routing of OPAs, allowing for a large number of antenna elements, while still allowing for sufficient space and flexibility for scalability of OPAs and PICs. Furthermore, the random and sparse arrangement of antenna elements on the OPAs can suppress side lobes of the optical signal beam. Furthermore, 2D optical beam steering can be achieved using fixed wavelength or finite range wavelength laser sources.

[0035] FIG. 1 illustrates an exemplary system 100 supporting photonic integrated circuit-based communication according to the present disclosure. As illustrated in FIG. 1, the system 100 may include two nodes 102 and 104 that communicate with each other optically. Each node 102 and 104 represents a ground, air, or space-based system that can transmit and / or receive data using optical communication. The nodes 102 and 104 may have unidirectional communication with each other, at least with respect to each other, where only one of the nodes 102 or 104 transmits and only the other node 104 or 102 receives. However, it will be appreciated that the nodes 102 and 104 may have bidirectional communication with each other if both the nodes 102 and 104 are capable of both transmitting and receiving optical signal beams, as illustrated in FIG. 1.

[0036] In this example, the node 102 includes an optical transmitter 106 that operates to generate an optical signal beam 108 that is typically used for communications or other purposes. For example, the optical transmitter 106 may encode information into the optical signal beam 108, such as by using appropriate optical amplitude, phase, frequency, and / or other modulation(s). The optical signal beam 108 is transmitted through free space or other transmission medium to the node 104, where an optical receiver 110 receives and processes the optical signal 108. For example, the optical receiver 110 may identify the optical amplitude, phase, frequency, and / or other modulation(s) in the optical signal beam 108 and use the identified modulation(s) to recover the information encoded in the optical signal beam 108. Any suitable type of modulation / demodulation scheme may be used herein to encode and decode the optical signal beam 108. In this example, because nodes 102 and 104 are bidirectional, the same process can be used in the opposite direction; i.e., optical transmitter 112 at node 104 generates and transmits optical signal beam 114 toward node 102, and optical receiver 116 at node 102 receives and processes the optical signal beam.

[0037] It should be noted that although the optical transmitter 106 and the optical receiver 116 are shown here as separate components, they may be integrated into a single optical transceiver 118, allowing the same PIC-based structure to be used for both transmitting and receiving the optical signal beams. Similarly, although the optical transmitter 112 and the optical receiver 110 are shown here as separate components, they may be integrated into a single optical transceiver 120, allowing the same PIC-based structure to be used for both transmitting and receiving the optical signal beams. As described in more detail below, each of the optical transmitters 106 and 112, the optical receivers 110 and 116, or the optical transceivers 118 and 120 includes at least one PIC-based optical phased array that is used to transmit and / or receive the optical signal beams 108 and 114.

[0038] The optical transmitters, receivers, and transceivers described in this disclosure may be used in numerous applications. For example, the optical transmitters, receivers, or transceivers may be used in data centers or telecommunications systems that rapidly transfer information between locations, including the transfer of large amounts of information over very long distances. The optical transmitters, receivers, or transceivers may be used in home or commercial electronics, biomedical devices, or advanced computing devices. The optical transmitters, receivers, or transceivers may be used in airplanes, drones, satellites, autonomous vehicles, rockets, missiles, or other commercial or defense-related systems. In general, this disclosure is not limited to any particular application of the optical transmitters, receivers, and transceivers.

[0039] Although Figure 1 illustrates an example of a system 100 supporting photonic integrated circuit based communications, various modifications may be made to Figure 1. For example, although only two nodes 102 and 104 are shown, system 100 may include any suitable number of nodes that may have any suitable unidirectional, bidirectional, or other communications with each other. Additionally, each node of system 100 may include any suitable number of optical transmitters, receivers, or transceivers that communicate via any number of optical signal beams. Additionally, system 100 is illustrated in a simplified form herein and may include any number of additional components in any suitable configuration as needed or desired.

[0040] 2 illustrates an example apparatus 200 supporting photonic integrated circuit based communications in accordance with the present disclosure. For ease of explanation, apparatus 200 may be depicted or described as being part of or used as part of one or more nodes 102 and 104 in system 100 of FIG. 1. However, apparatus 200 may be used as, within, or in conjunction with any other suitable device or system.

[0041] As shown in FIG. 2, the device 200 can include a housing 202 that can be used to house and protect other components supporting PIC-based communications. The housing 202 can be formed in any suitable manner from any suitable material(s), such as one or more metals. The housing 202 can also have any suitable size, shape, and dimensions. The housing 202 can be secured to a support structure 204, which represents any suitable structure on or to which the housing 202 can be secured. A cover 206 can be removably coupled to the housing 202 to provide selective access to an interior space of the housing 202. The housing 202 can define at least one aperture 208 that can pass an outgoing or incoming optical signal beam, such as optical signal beams 108 and 114. In this particular example, there is a single aperture, however, the housing 202 may define multiple apertures (eg, one for transmitting and one for receiving).

[0042] At least one optical transmitter, optical receiver, and / or optical transceiver is positioned within the housing 202 and communicates through at least one aperture 208. For example, in some cases, the device 200 can include at least one optical transmitter 210a (which can represent at least one example of the optical transmitter 106 or 112) and at least one optical receiver 210b (which can represent at least one example of the optical receiver 110 or 116). In one example, the optical transmitter 210a and the optical receiver 210b can be positioned side-by-side on a common support 212, thereby enabling the optical transmitter 210a and the optical receiver 210b to transmit or receive an optical signal beam, respectively, through the aperture 208. In other cases, the device 200 can include at least one optical transceiver 214 (which can represent at least one example of the optical transceiver 118 or 120) on the support 216, where the optical transceiver 214 can communicate through the aperture 208. The optical transceiver 214 may support transmitting optical signal beams at one or more wavelengths and receiving optical signal beams at one or more different wavelengths. Those skilled in the art will appreciate that any suitable combination of at least two optical transmitter(s), optical receiver(s), and / or optical transceiver(s) may be used in the apparatus 200.

[0043] Although FIG. 2 illustrates an example of an apparatus 200 supporting photonic integrated circuit-based communication, various modifications may be made to FIG. 2. PIC-based communication may be used in or by a wide range of devices and is not limited to the particular apparatus illustrated herein. For example, the housing 202 may alternatively be formed as a rotatable gimbal that may redirect one or more optical transmitters, optical receivers, or optical transceivers as needed or desired. Additionally, the apparatus 200 may include components that support the generation and transmission and / or reception and processing of beacon optical signal beams, which may be used to help identify a location to which the apparatus 200 should be directed to perform optical communications or send other signals.

[0044] 3-5 illustrate an example of a photonic integrated circuit-based optical device 300 according to the present disclosure. For ease of explanation, the optical device 300 is described as being used to implement one of the optical transmitter 210a, the optical receiver 210b, or the optical transceiver 214 of FIG. 2, which may be used in the system 100 of FIG. 1. However, the optical device 300 may be used in any other suitable apparatus and in any other suitable system.

[0045] 3, the optical device 300 includes a package 302 that encloses and protects the electronic and optical components of the optical transmitter 210a, the optical receiver 210b, or the optical transceiver 214. The package 302 may be formed in any suitable manner from any suitable material(s), such as one or more metals, and may have any suitable size, shape, and dimensions, and may have any suitable form, without any limitation intended.

[0046] The package 302 may include an optical window 306 that is at least partially optically transparent to the optical signal beam transmitted from or received by the optical device 300. The optical window 306 may be formed in any suitable manner from any suitable material(s), such as borosilicate glass or other glass, and the optical window 306 may have any suitable size, shape, and dimensions.

[0047] The package 302 may also include one or more electrical connections 308 that may be used to carry one or more electrical signals between the interior and exterior of the package 302, where the one or more electrical signals may be used for any suitable purpose, such as to control one or more operations of the optical device 300. As a specific example, the one or more electrical signals may be used to control a phase and / or amplitude modulator to control the phase or amplitude of an optical signal beam from an antenna element of a photonic integrated circuit in the optical device 300. The package 302 may further include one or more optical input / outputs 310 (e.g., optical fibers) that may be used to provide one or more input signals to the optical device 300 and / or receive one or more output signals from the optical device 300. The one or more input signals may carry information to be transmitted from the optical device 300. The one or more output signals may carry information received by and recovered by the optical device 300. In this example, there are two fiber input / outputs 310, but the optical device 300 may include a single fiber input / output 310 or more than two fiber input / outputs 310. Note, however, that if all light generation and processing is performed using components within the package 302, the fiber input / output 310 is not required. In this case, electrical connections 308 may be used to carry information to and from the optical device 300.

[0048] As shown in FIG. 4, the photonic integrated circuit 402 is positioned within the package 302, i.e., in a location where the photonic integrated circuit 402 can transmit and / or receive optical signal beams through the optical window 306. As described below, the photonic integrated circuit 402 can be used to support the transmission and / or reception of optical signal beams, depending on the design of the photonic integrated circuit 402. The photonic integrated circuit 402 can also support some additional optical functions as needed or desired. The photonic integrated circuit 402 can be formed in any suitable manner from any suitable material(s), such as silicon, indium phosphide, or gallium arsenide. The photonic integrated circuit 402 can also have any suitable size, shape, and dimensions. As a specific example, the photonic integrated circuit 402 is square and has a side length of about 40 mm, although any other suitable size and shape can be used herein.

[0049] The fiber mount 404 can be used to couple to the optical fiber 406 at a location where the optical fiber 406 can provide and / or receive optical signals from the photonic integrated circuit 402. For example, the optical fiber 406 can provide an optical signal from a source laser to the photonic integrated circuit 402 for use during launch of a transmission of an optical signal beam. Additionally or alternatively, the optical fiber 406 can provide an optical signal received by the photonic integrated circuit 402 to a receiver for processing. Each fiber mount 404 can include any suitable structure configured to be coupled to the optical fiber 406. Each optical fiber 406 represents any suitable length of optical media configured to transfer optical signals to and from the photonic integrated circuit 402. It is noted that while four fiber mounts 404 and optical fibers 406 are shown here, the optical device 300 can include one, two, three, or more than four fiber mounts 404 and optical fibers 406. It is also noted that the fiber mounts 404 and / or optical fibers 406 are not required if all light generation and processing is performed using components of the photonic integrated circuit 402.

[0050] The electronic control board 408 includes electronic components, such as one or more integrated circuit chips and other components, that control the operation of the photonic integrated circuit 402. For example, the electronic control board 408 may include one or more components that calculate a desired phase of an optical signal beam generated by an antenna element of the photonic integrated circuit 402, thereby enabling the electronic control board 408 to control a beamforming or beamsteering operation from the PIC. Additionally or alternatively, the electronic control board 408 may include one or more components that calculate a desired phase to be applied to an optical signal received by an antenna element of the photonic integrated circuit 402, thereby enabling the electronic control board 408 to control a wavefront reconstruction operation. The electronic control board 408 includes any suitable components configured to perform one or more desired functions associated with the photonic integrated circuit 402.

[0051] As shown in FIG. 5, the photonic integrated circuit 402 may itself include a number of array elements 502, which represent PIC unit cells of the photonic integrated circuit 402. Each array element 502 may be configured to transmit or receive one or more optical signals. The photonic integrated circuit 402 may include any suitable number of array elements 502, and in some cases may include up to and including a very large number of array elements 502. In some embodiments, for example, the photonic integrated circuit 402 may include an array of elements 502 up to a size of 1024×1024 (i.e., more than one million array elements 502) or more. The size of the photonic integrated circuit 402 is based at least in part on the number and size of the array elements 502. As mentioned above, in some cases, the photonic integrated circuit 402 may be a square with a side length of about 40 mm. However, the photonic integrated circuit 402 may be scaled to smaller or larger sizes (e.g., about 2.5 cm by about 2.5 cm), and even larger sizes (e.g., about 20 cm by about 20 cm or about 30 cm by about 30 cm or more, these sizes are not intended to be limiting in any way) depending on manufacturing capabilities.

[0052] Each array element 502 may include an antenna element 504 configured to physically transmit and / or receive one or more optical signal beams to or from one or more external devices or systems. For example, each antenna element 504 may represent a nanophotonic antenna or other antenna element that transmits at least one optical signal beamlet or receives optical energy within an array gain envelope without a lens or with one or more lenses or other optical devices configured to focus or otherwise process at least one optical signal beam. Depending on the implementation, the antenna elements 504 may also be referred to as emitters in a transmit array or receivers in a receive array. Each antenna element 504 may have any suitable size, shape, and dimensions. In some cases, the emitting / receiving surface of the antenna element 504 may be about 2 μm to about 4 μm in diameter.

[0053] Here, each antenna element 504 is coupled to a signal path 506. The signal path 506 is configured to transport optical signals to and from the antenna elements 504. For example, the signal path 506 may provide an optical signal to the antenna elements 504 for transmission. Additionally or alternatively, the signal path 506 may provide an optical signal received by the antenna elements 504 to a photodetector or other component for processing. Each signal path 506 includes any suitable structure configured to transport an optical signal, such as an optical waveguide. Note that only a portion of the signal path 506 may be shown in FIG. 5 because the signal path 506 may vary based on how the associated array element 502 is designed and positioned within the photonic integrated circuit 402.

[0054] One or more modulators 508 are provided for each antenna element 504 and may be used (among other things) to control the phase and / or amplitude, or both, of an optical signal transmitted or received by the associated antenna element 504 (depending on the placement and application or use). For example, in an example where the antenna element 504 is transmitting, the modulator 508 may be used to achieve a desired phase of an outgoing optical signal beam and perform beamforming or beamsteering. In an example where the antenna element 504 is receiving, the modulator 508 may be used to apply phase control to an incident wavefront of a received optical signal and to decompose or reconstruct the wavefront. In an example where both receiving and transmitting are occurring, the modulator 508 may be used to achieve a desired phase of an outgoing optical signal beam and to apply phase control to an incident wavefront of a received optical signal. Each modulator 508 may include any suitable structure configured to modulate the phase and / or amplitude of an optical signal, such as a resonant micro-ring modulator or a PN junction micro-ring modulator. In some cases, each modulator 508 may be a resonant micro-ring modulator having a diameter of approximately 4-6 μm, although modulators of other sizes may be used.

[0055] The modulator 508 of the photonic integrated circuit 402 may be electrically coupled to a digital read-out integrated circuit (DRIIC) layer 510, which is used to provide the modulator 508 with an electrical signal for controlling the phase and / or amplitude modulation applied by the modulator 508 to the optical signal entering or exiting the modulator. The (DRIIC) designs described herein may be tailored to the unique characteristics of optical phased arrays. Instead of using large breakout circuit boards and digital-to-analog converters, the DRIIC designs may have a low profile and may support operations such as flip-chip bonding to the photonic integrated circuit. In some cases, the DRIIC designs may integrate all PIC-related electronic controls into a hybrid or monolithic design. The DRIIC designs may also support a unit cell architecture, in which each DRIIC unit cell corresponds to and interacts with a corresponding PIC unit cell. This supports scalability of the DRIIC designs as well as the PIC designs to any suitable size. Overall, the DRIIC designs are useful for supporting a variety of functions, such as beamforming and beamsteering, in a compact package. Photonic integrated circuit 402 may be coupled to DRIIC layer 510 using any mechanism for electrically coupling photonic integrated circuit PIC 402 and DRIIC layer 510 .

[0056] In this example, the DRIIC layer 510 includes a number of individual DRIIC cells 512, each of which may be associated with (and in some cases may have approximately the same size as) a corresponding one of the array elements 502. The DRIIC cells 512 control the phase modulation applied by the modulators 508 of the array elements 502. The DRIIC cells 512 may essentially function as digital-to-analog conversion devices, converting digital programming (such as 1-bit, 2-bit, 8-bit, or other digital values) to appropriately scaled direct current (DC) analog voltages spanning a particular voltage range. As a specific example, the DRIIC cells 512 may operate to convert digital values ​​to an appropriate DC analog voltage between 0V and 3.3V, although other voltages (including negative voltages) may also be supported depending on the implementation.

[0057] In this example, each DRIIC cell 512 may include a register 514 that may be configured to store values ​​associated with different phase shifts and / or amplitude changes to be applied by the modulator 508 of its corresponding array element 502. To provide a desired phase shift, an appropriate value is selected from the register 514 and provided to two amplifiers 516 and 518, which generate an output voltage to supply to the associated modulator 508. The output voltage controls the phase shift provided by the associated modulator 508. Different values ​​from the register 514 are provided to the amplifiers 516 and 518 over time, resulting in different output voltages being applied to the associated modulator 508. In this manner, each DRIIC cell 512 may cause its associated modulator 508 to provide different phase shifts over time to support various functions such as beamforming, beam steering, or wavefront reconstruction.

[0058] In some embodiments, each DRIIC cell 512 may be used to provide a relatively small number of different output voltages to its associated modulator 508. For example, in some cases, each DRIIC cell 512 may have its associated modulator 508 provide four, or even two, different phase shifts, although other numbers of output voltages and associated phase shifts may be supported, such as supporting up to 256 or more different phase shifts. Also, the output voltages provided to the modulators 508 in different DRIIC cells 512 may be different, even if the modulators 508 provide the same phase shift, which may be due to factors such as manufacturing tolerances. The actual output voltages used for each modulator 508 may be selected during calibration, so that the appropriate values ​​can be stored in each register 514.

[0059] In this example, the actual value of each DRIIC cell 512 provided by register 514 over time to amplifiers 516 and 518 can be controlled using a demultiplexer 520. Each demultiplexer 520 receives a stream of calculated array phase shifts 522 and outputs the phase shift 522 that needs to be applied by the modulator 508 associated with that DRIIC cell. The phase shifts 522 output by the demultiplexer 520 can identify or otherwise use the phase shifts from the register 514 to select and output the particular values ​​to the amplifiers 516 and 518. The calculated array phase shifts 522 here can be provided by one or more external components, such as the electronic control board 408 or an external component in communication with the electronic control board 408. Although not shown here, array-level deserialization circuitry can be used to separate and fan out the high speed digital signal to an array of individual DRIIC cells 512.

[0060] Each register 514 includes any suitable structure configured to store and retrieve a value. Each amplifier 516 and 518 includes any suitable structure configured to generate a control voltage or other control signal based on an input. Each demultiplexer 520 includes any suitable structure configured to select and output a value.

[0061] It should be noted that this represents one example of how the modulator 508 of the array element 502 may be controlled. In general, any suitable technique may be used to provide an appropriate control voltage or other control signal to the modulator 508 for use in controlling the phase shift it provides. For example, in the approach shown in Figure 5, the value applied to the amplifiers 516 and 518 may be stored in a register 514 and retrieved as needed, allowing an external component to provide an indicator of the desired value to be retrieved to the DRIIC cell 512. In other embodiments, the external component may provide a digital value that is converted to an analog value by a different circuit.

[0062] Various electrical connections 524 are provided in or with the DRIIC layer 510. The electrical connections 524 may be used to provide electrical signals to the DRIIC cells 512, such as when receiving a high speed digital signal including the calculated array phase shifts 522 of the DRIIC cells 512. Any suitable number and arrangement of electrical connections 524 may be used herein. A thermal spreader 526 may be positioned in thermal contact with the DRIIC layer 510 to provide a more consistent temperature across the DRIIC layer 510 and the photonic integrated circuit 402. The thermal spreader 526 may also provide thermal energy to the DRIIC layer 510 to heat the DRIIC layer 510 and the photonic integrated circuit 402 and help maintain a substantially constant temperature of the photonic integrated circuit 402. The thermal spreader 526 may be formed in any suitable manner from any suitable material(s), such as one or more metals, such as copper. The thermal spreader 526 can have any suitable size, shape, and dimensions.

[0063] 3-5 illustrate an example photonic integrated circuit-based optical device 300, various modifications may be made to Figures 3-5. For example, one or more photonic integrated circuits may be packaged in any other suitable manner, positioned relative to other components in any other suitable manner, and coupled to other components in any other suitable manner. Also, any other suitable modulation control approach and any other suitable thermal management approach may be used with one or more photonic integrated circuits.

[0064] 6 and 7 illustrate a more specific implementation of a photonic integrated circuit-based optical system including the photonic integrated circuit-based optical device 300 of FIGS. 3-5 according to the present disclosure. In particular, FIGS. 6 and 7 illustrate an exemplary architecture 600 that may be implemented within the optical device 300. As shown in FIG. 6, the architecture 600 may include a source laser 602, an OPA 604, and a receiver 606. The source laser 602 is an electromagnetic radiation source (i.e., a source of optical energy) that generally operates to generate and provide optical signals (e.g., electromagnetic radiation, or in other words, optical energy) to the OPA 604, which uses those optical signals to transmit outgoing optical signals. The OPA 604 generally operates to transmit outgoing optical signals and receive incoming optical signals. The receiver 606 generally operates to process the incoming optical signals. These components enable architecture 600 to support optical transceiver functionality, however, if only optical transmitter or only optical receiver functionality is desired, some components (e.g., either source laser 602 or receiver 606) can be removed from architecture 600.

[0065] In this example, the source laser 602 may include a laser 608 operative to generate a low power input beam. The laser 608 may include any suitable structure configured to generate a laser output, such as a distributed feedback (DFB) diode laser. The low power input beam may have any suitable power level based on the laser 602 used in a particular application. In some cases, the low power input beam may have a power level of tens or tens of milliwatts to a hundred or hundreds of milliwatts, although these values ​​are for illustrative purposes only. Also, in some cases, the laser 602 may be fabricated using at least one group III element and at least one group V element, and thus may be referred to as a "III-V" laser. However, any other suitable materials may be used to fabricate the laser 602. When the low power input beam is provided to an electro-optic modulator (EOM) 610, the low power input beam may be modulated based on an input electrical signal. The EOM 610 may provide any suitable modulation here, such as when the EOM 610 is implemented as a Mach-Zehnder modulator (MZM) that provides amplitude modulation.

[0066] Splitter 612 typically operates to split a modulated input beam into optical signals traveling via different optical paths. In this example, splitter 612 includes a hierarchical arrangement of splitters 612a-612n, each capable of receiving and splitting an optical input to generate two optical outputs of substantially equal power. It is noted that the number of splitters 612a-612n and the number of hierarchical levels of splitters 612a-612n can vary based on the number of optical signals to be generated. For example, there can be five levels of splitters if 32 optical signals are desired, or six levels of splitters if 64 optical signals are desired. However, it is noted that any suitable number of splitters can be used to generate other numbers of optical signals. It is also noted that any other suitable structure(s) can be used to split the optical signals, such as a multimode interferometer or a coupler tree.

[0067] The optical signals from the splitter 612 may be phase shifted using an array of phase shifters 614, with each phase shifter 614 capable of shifting the phase of one of the optical signals. Each phase shifter 614 includes any suitable structure configured to phase shift the optical signal, such as a resonant microring modulator. In some embodiments, the resonant microring modulator may be silicon based and may have a diameter of about 5 microns to about 6 microns, although other implementations of the phase shifter 614 may also be used.

[0068] The phase-shifted optical signals are provided to an array of semiconductor optical amplifiers (SOAs) 616. Each semiconductor optical amplifier 616 amplifies one of the phase-shifted optical signals to generate a high-power version of that optical signal. Each semiconductor optical amplifier 616 represents any suitable semiconductor-based amplifier configured to amplify an optical signal. Each of the amplified optical signals may have any suitable power level based on the semiconductor optical amplifier 616 being used. In some cases, the amplified optical signals may each have a power level of about 100 mW, although this value is for illustrative purposes only. The amplified optical signals may be combined and transmitted via optical waveguide 618 to allow source coherent combining of the outputs from the semiconductor optical amplifiers 616 (as the amplifiers 616 form a phase-locked array of SOAs). The combined signal is provided to a circulator 620, which provides the combined signal to the OPA 604.

[0069] In the OPA 604, the combined signal is split by the splitter 622 such that substantially equal first portions of the combined signal are provided to the two waveguides 624a-624b. Here, the waveguides 624a-624b can have substantially the same length such that there is little or no phase difference between the first portions of the combined signal exiting the waveguides 624a-624b. In this example, the photonic integrated circuit 402 is implemented using supercells 626, with each supercell 626 including a subset of the array elements 502. In some embodiments, for example, each supercell 626 can include a 32×32 arrangement of the array elements 502, although other numbers and arrangements of the array elements 502 can be used in each supercell 626. In this particular example, the photonic integrated circuit 402 includes 64 supercells 626, although other numbers of the supercells 626 can be used. Multiple supercells 626 can be driven using the same portion of the combined signal from the source laser 602, helping to simplify phase control and other operations in the architecture 600. The ability to jointly drive all array elements 502 within a supercell 626 makes it possible to control the transmit power of the array elements 502 in each supercell 626, for example, by amplitude modulation of that supercell 626.

[0070] In the OPA 604, the laser output from the source laser 602 may be split by a splitter 622 such that a substantially equal first portion of the combined signal is provided to two waveguides 624a and 624b. Here, the waveguides 624a and 624b may have substantially the same length such that there is little or no phase difference between the first portions of the combined signal exiting the waveguides 624a and 624b. In this example, the photonic integrated circuit 402 may be implemented using supercells 626, with each supercell 626 including a portion of the array elements 502. In some embodiments, for example, each supercell 626 may include a 32×32 arrangement of the array elements 502, although other numbers and arrangements of the array elements 502 may be used in each supercell 626. In this particular example, the photonic integrated circuit 402 includes 64 supercells 626, although other numbers of the supercells 626 may be used. Multiple supercells 626 can be driven using the same portion of the combined signal from the source laser 602, helping to simplify phase control and other operations in the architecture 600. The ability to jointly drive all array elements 502 within a supercell 626 makes it possible to control the transmit power of the array elements 502 in each supercell 626, for example, by amplitude modulation of that supercell 626.

[0071] To drive the supercell 626 using the combined signal from the source laser 602, the waveguides 624a and 624b provide a first portion of the combined signal to splitters 628a and 628b (such as 1×8 optical splitters) that split the first portion of the combined signal into a second, larger portion of the combined signal. Additional splitters 630a and 630b (such as 8×32 splitters) split the second portion of the combined signal into an even larger, third portion of the combined signal. This results in the creation of 64 optical signals that can be used to drive the supercell 626. It should be noted that this arrangement of 1×8 and 8×32 splitters is just one example of how the supercell 626 in this particular photonic integrated circuit 402 can be driven. Other approaches can also be used to drive the photonic integrated circuit 402, including approaches using other numbers or arrangements of splitters. The particular approach shown in FIG. 6 is just one example of how the supercell 626 of this particular photonic integrated circuit 402 can be driven.

[0072] To compensate for the different optical path lengths to reach the different supercells 626, time delays 632a and 632b are provided between splitters 630a and 630b and supercells 626. For example, assuming that each row of supercells 626 in photonic integrated circuit 402 is driven using four outputs from splitter 630a and four outputs from splitter 630b, without compensation, different outputs from splitters 630a and 630b may arrive at different supercells 626 at different times, resulting in undesirable phase differences and reducing the throughput of architecture 600. Time delays 632a and 632b represent helical or other optical paths that delay at least a portion of the outputs from splitters 630a and 630b such that the outputs from splitters 630a and 630b arrive at all supercells 626 at approximately the same time. For example, time delay paths 632a and 632b may delay signals to closer supercell 626 by a larger amount and may delay signals to more distant supercell 626 by a smaller amount or not at all. Optical signals received at supercell 626 are used by supercell 626 to generate an outgoing optical signal.

[0073] The supercell 626 can receive incident optical signals, which can be transmitted through the circulator 620 via the waveguides 624a-b to the receiver 606. In this example, the receiver 606 can include at least one photodetector 634, such as at least one photodiode, that converts the received incident optical signal into a current. The transimpedance amplifier 636 can convert the current into a voltage, which can then be further processed (e.g., to recover information contained in the incident optical signal).

[0074] It should be noted that various components of the OPA 604 and source laser 602 may be fabricated from different materials to allow for different optical power levels to be used in the architecture 600. For example, the components of the source laser 602 may be fabricated using silicon nitride, germanium, or other materials that allow the source laser 602 to generate a relatively high-power combined beam for the OPA 604. In the OPA 604, the waveguides 624a and 624b and the splitters 628a and 628b may similarly be fabricated using silicon nitride or other materials that support the transmission and splitting of the relatively high-power combined beam from the source laser 602. The splitters 630a and 630b may be fabricated using silicon (rather than silicon nitride) or other materials that can split a low-power optical signal (since the optical energy from the source laser 602 has already been split at this point). However, the components of the architecture 600 may be fabricated from any other suitable materials. Also, it should be noted that various components of architecture 600 may or may not be manufactured using one or more common materials.

[0075] In some embodiments, all components in the architecture 600 of FIG. 6 can be implemented in an integrated manner, such as when implemented using a single integrated electrical and photonic chip. As discussed above, for example, various components of the architecture 600 can be fabricated using silicon and silicon nitride, allowing for fabrication using standard silicon-based processes. When implemented in an integrated manner, the architecture 600 can be implemented using a single photonic integrated circuit chip and may not require components such as the fiber input / output section 310, the fiber mount 404, and the optical fiber 406. However, integration of components in the architecture 600 is not necessarily required. Thus, for example, the source laser 602 can be implemented off-chip or replaced using a standard erbium-doped fiber amplifier laser or other external laser. As another example, the receiver 606 can be implemented off-chip.

[0076] 6 and 7 show another example of a particular implementation of the photonic integrated circuit-based optical device of FIGS. 3-5, although various modifications may be made to FIGS. 6 and 7. For example, this particular embodiment logically divides the photonic integrated circuit 402 in half by using two waveguides 624a-b, two sets of splitters 628a-b, 630a-b, and two sets of time delays 632a-b. However, the photonic integrated circuit 402 may be logically divided into other numbers of parts or may not be logically divided at all. Additionally, various components of FIGS. 6 and 7 may be combined, further subdivided, duplicated, omitted, or rearranged, and additional components may be added according to particular needs.

[0077] One portion 638 of the supercell 626 is identified in FIG. 6 and is shown in more detail in FIG. 7 in at least one exemplary arrangement. As shown in FIG. 7, this portion 638 of the supercell 626 includes an 8×8 arrangement of array elements 502, with each array element 502 having a structure similar to that shown in FIG. 5. As can be seen, the structure of the array elements 502 can be varied as needed or desired. The array elements 502 are fed using a waveguide 700. As shown, the waveguide 700 can include a main waveguide 702. The main waveguide 702 can be in optical communication with the source laser 602 and can be configured to receive electromagnetic radiation (e.g., an optical signal) from the source laser 602. A splitter 704 can be positioned along the main waveguide 702 and can split off a portion of the optical signal propagating within the main waveguide 702. The portions of the optical signal split off from the main waveguide 702 are provided through branch waveguides 706a-706h that are optically coupled to the main waveguide 702 at different locations along the main waveguide 702 and coupled to the main waveguide 702 by splitters 704. Splitters 708 may be positioned along the branch waveguides 706a-706h to further split off portions of the optical signal within each branch waveguide 706a-706h. Ideally, the splitters 704 and 708 are configured such that each of the array elements 502 receives an approximately equal portion of the optical signal input to the main waveguide 702. In some embodiments, the main waveguide 702, the branch waveguides 706a-706h, and the splitters 704, 708 may be formed from silicon, although other materials may be used.

[0078] Note that if each supercell 626 includes array elements 502 in a 32 by 32 arrangement, then each supercell 626 includes 32 rows of array elements 502, with each row including 32 array elements 502. Thus, portion 638 shown in Figure 7 is replicated 16 times within each supercell 626. However, each of the supercells 626 can have a different number and arrangement of array elements 502, as needed or desired.

[0079] In FIG. 7, it can be seen that there are different path lengths between the input of the main waveguide 702 (located below the main waveguide 702 in FIG. 7) and the different array elements 502. In this particular example, the shortest path length is between the input of the main waveguide 702 and the bottom left array element 502, and the longest path length is between the input of the main waveguide 702 and the top right array element 502. As with the supercell 626 itself, without compensation, these different path lengths will cause different portions of the optical signal to arrive at the array element 502 at different times. In some cases, a phase shift provided by a modulator 508 in the array element 502 can be used to compensate for the different path lengths between the input of the main waveguide 702 and each array element 502. Additionally or alternatively, a linear or other phase shifter can be used to compensate for the different path lengths between the input 701 of the main waveguide 702 and each array element 502.

[0080] Antenna element spacing in optical phased arrays As shown in FIG. 7, each array element 502 of the portion 638 of the OPA 604 may be spaced at an irregular (e.g., non-periodic) location along the waveguide 700. In other words, the array elements 502 are not spaced a fixed distance from one another. In this example, each branch waveguide 706a-706h may be optically coupled to a respective array element subset 502a-502h. Each array element 502 in the first array element subset 502a may be optically coupled to the first branch waveguide 706a. Further, each array element 502 in the second array element subset 502b may be optically coupled to the second branch waveguide 706b, each array element 502 in the third array element subset 502c may be optically coupled to the third branch waveguide 706c, and so on, and each array element in the eighth array element subset 502h may be optically coupled to the eighth branch waveguide 706h. 7 shows eight subsets (e.g., 502a-502h) and eight branch waveguides (e.g., 706a-706h), although it should be understood that any suitable number and arrangement of branch waveguides and subsets of array elements may be used herein.

[0081] 7-9 illustrate the non-periodic placement and spacing of the array elements 502 within the portion 638 of the OPA 604. As can be seen in Fig. 7, the array elements 502 may be spaced apart within the OPA 604 at locations that do not have a regular, discernible pattern. Each array element 502 may be positioned within the OPA 604 at a different spacing from other adjacent array elements 502.

[0082] FIG. 8 illustrates a portion of the array elements 502 of FIG. 7. As shown, each of the individual array elements 502 can have a different spacing from adjacent / neighboring array elements 502. For example, a first subset of array elements 502a can include array elements a1-a8, each coupled to a first branch waveguide 706a. As shown, array elements a1 and a2 are spaced apart from one another along axis N by a distance x1. Additionally, array elements a2 and a3 are spaced apart from one another by a distance x2. Array elements a3 and a4 are spaced apart from one another by a distance x3. Array elements a4 and a5 are spaced apart from one another by a distance x4. Array elements a5 and a6 are spaced apart from one another by a distance x5. Array elements a6 and a7 are spaced apart from one another by a distance x6. Array elements a7 and a8 are spaced apart from one another by a distance x7. No discernible pattern is apparent from the spacing of array elements a1-a8. Each of the distances x1-x7 may be different from one another, and there is no progression or decrease in the distances x1-x7 moving from array element a1 to array element a8. Thus, the spacing between array elements a1-a8 is random, or more specifically, pseudo-random.

[0083] As used herein, "pseudo-random" is intended to mean that the spacing of the array elements 502 does not have any obvious spacing pattern or periodicity within the array. Instead, each array element 502 is spaced relative to one another in such a way that no set distance, spacing, or positioning is prescribed between adjacent array elements. However, it should be understood that pseudo-random does not mean placing the array elements 502 within the OPA 604 without considering or planning where the array elements 502 should be placed. Instead, the array elements are positioned at locations that are calculated to achieve a particular goal, metric, or property of the OPA 604 based on the positioning of the array elements 502. In the present disclosure, the array elements are "pseudo-random" positioned to suppress side lobes or grating lobes within the radiated optical signal beam transmitted from the antenna elements 504 of the array elements 502. Furthermore, these locations are determined using an algorithm to establish a peak-to-side lobe intensity ratio of the radiated optical beam to be above a predetermined threshold. The predetermined threshold can be set to any value known by one skilled in the art to be suitable for a particular application. For example, the threshold may be at or near 60 dB, although larger and / or smaller values ​​may be suitable. For example, the threshold may be in the range of 30-90 dB or between 30-90 dB depending on the application. Smaller values ​​may be set, e.g., values ​​below 30 dB, such as 9.6 dB shown in FIG. 11(d), and values ​​of about 30 dB or less shown in FIG. 12(B), may be used as the threshold. If further grating lobe suppression is required, values ​​of 30 dB or less may be used. In general, the comparison between the intensity of the main lobe and the intensity of the grating lobe may be set to 1000:1 to ensure that the intensity of the grating lobe is much smaller than the main lobe. However, it should be understood that, depending on the application, different thresholds or peak-to-side lobe ratios may be used if the user so desires. Any desired ratio or intensity threshold may be used without any intended limitation.

[0084] Similar to array elements a1-a8 of subset 502a, array elements b1-b8 and array elements c1-c8 in each of subsets 502b and 502c are positioned in pseudo-random positions such that there is no discernible pattern in the spacing of the array elements, which may also be true for subsets 502d-502h.

[0085] Additionally, each array element 502 in one subset (e.g., 502a) may have a pseudo-random (e.g., non-periodic) spacing relative to the array elements 502 in another subset (e.g., 502b, 502c, etc.). For example, as shown in FIG. 8, the first array elements (e.g., a1, b1, and c1) in each of the subsets 502a, 502b, and 502c are non-periodically positioned relative to one another. In the example shown in FIG. 8, array element b1 is closer to the main optical waveguide 702 than both array elements a1 and c1. Furthermore, array element a1 is closer to the main optical waveguide 702 than array element c1. The positions of array elements a1, b1, and c1 relative to one another are pseudo-random, exhibiting no discernible pattern along axis M. It will be appreciated that the positions and spacing of other columns of array elements (e.g., corresponding array elements by order in each of subsets 502a, 502b, and 502c) are also non-periodic and pseudo-random. In other words, array elements a2, b2, and c2 are non-periodic spaced relative to one another, array elements a3, b3, and c3 are non-periodic spaced relative to one another, and so on, array elements a8, b8, and c8 are non-periodic spaced relative to one another.

[0086] 7 and 8 show non-periodic positioning of the array elements 502 relative to one another in the horizontal direction on the OPA 604. In an additional view shown in FIG. 9, the positioning of the array elements 502 relative to one another in the vertical direction may also be non-periodic. For example, in subset 502c, each of array elements c1, c2, and c3 are spaced apart at a different height relative to branch waveguides 706a, 706b, and 706c along axis Y. Similarly, in subset 502b, each of array elements b1, b2, and b3 are spaced apart at a different height relative to branch waveguides 706a, 706b, and 706c. Similarly, in subset 502a, array elements a1 and a2 are spaced apart at a different height relative to branch waveguides 706a, 706b, and 706c than array element a3. It should be understood that the spacing and positioning of the array elements 502 is pseudo-random even if two or more adjacent array elements 502 are spaced the same distance apart relative to another array element or waveguide. For example, array elements a1 and a2 in the first subset 502a may have the same distance from the waveguide 706a. This does not destroy the pseudo-randomness of the spacing of the OPAs 604 of the array elements 502. In other words, multiple array elements 502 may have similar positioning relative to particular landmarks (e.g., waveguides and / or other array elements) in the array and still be considered pseudo-random spacing / positioning.

[0087] Sidelobe Suppression and Array Scalability As mentioned above, the pseudo-random spacing of the array elements 502 is intended to achieve a narrow optical signal beam emitted from the OPA 604 while suppressing side / grating lobes that can cause interference and / or undesired intensity. In the field of antenna technology, where signals are propagated using electromagnetic radiation and transmitted and received by antennas, the distance between antenna elements in the array needs to be half the wavelength of the electromagnetic radiation used to carry the signal in order to adequately suppress grating lobe interference on the main signal beam. For example, for frequencies in the RF spectrum, where the electromagnetic radiation may have a wavelength of about 1 meter to 10 kilometers, spacing the array elements at half wavelength intervals (e.g., 1 meter to 5 kilometers) is readily achievable. Even when the wavelength is 1 cm (i.e., 30 GHz), spacing the array elements at half wavelength distances is readily achievable. However, in the case of photonic integrated circuits (PICs) and optical phased arrays (OPAs), where the wavelength of the optical signal is on the order of 0.5 to 10 micrometers, it is technically difficult to separate the array elements by less than half a wavelength in more than one dimension to suppress side lobe interference due to manufacturing difficulties and a lack of space on the PIC.

[0088] FIG. 10 provides a demonstrative illustration of the problem of radiating an optical signal beam from a photonic integrated circuit (PIC) 800. As shown, the PIC 800 can include an optical phased array (OPA) 801, which can include multiple antenna elements radiating a steerable optical signal beam 802 including a main optical signal beam 803. In the OPA 801, the spacing between antenna elements is greater than half the wavelength of the optical signal beam 802, so that in addition to the main optical signal beam 803, large grating lobes 804, which are a type of side lobe, are also radiated. The grating lobes 804 are undesirable, especially for steerable and directional optical signal beams, which are intended to direct an optical signal to a desired location with high accuracy and multiple desired trajectories. It is desirable to suppress the side lobes 804 of the optical signal beam 802 to prevent signal interference and provide deterministic beamforming and control.

[0089] FIG. 11 shows (a) near-field antenna elements 504 and (b) far-field patterns of radiated optical signal beam 802 formed from a regular array of emitters (antenna elements) 504. Here, the emission of optical radiation in the near field (a) is shown, and (b.) the resulting grating lobes at 804 are shown. Graphs (c) and (d) of FIG. 11 show exemplary intensities of the main optical beam 803 as well as the grating and side lobes 804 according to actual (c) and theoretical (d) far-field beam patterns. As can be seen from FIG. 11, the side lobes 804 can have significant intensity and thus can cause interference and lack of clarity from the side lobes 804 during steering and reception of the main optical beam 803 by the receiver. Therefore, it is desirable to suppress the side lobes 804 of the optical signal beam 802 in order to maintain control of the directionality of the communication beam of the main optical signal beam 803 and to avoid interference with the signal.

[0090] As mentioned above, to suppress the grating lobes 804, the spacing of the nanoantennas in the OPA needs to be half the wavelength of the optical signal beam 802. However, in optical applications where the wavelength of the optical signal beam 802 is very small (e.g., a few micrometers), this is not practical since the wavelength is smaller than the physical size of the array elements 502. Therefore, to avoid the interference caused by the grating lobes 804, a pseudo-random sparse array can be designed and implemented as described herein where the array elements are spaced apart by a spacing greater than half the wavelength of the optical signal beam. This has the advantage of suppressing the side / grating lobes 804 around the optical signal beam main lobe 803. The pseudo-random spacing of the nanoantennas of the OPA 604 described herein allows the side lobes of the main optical signal beam to destructively interfere with each other, thus suppressing the side lobes, thereby allowing the main optical signal beam from the OPA 604 to reach the far-field plane without undesired grating / side lobes.

[0091] To ensure adequate side lobe suppression, the placement of each of the array elements 502, including the nano-antennas 504 and phase modulators 508, is not random. That is, although there appears to be no discernible pattern in the placement of the array elements 502, the array elements are actually positioned deterministically using an iterative algorithm to establish a desired layout and positioning of the array elements 502 within the OPA 604, thereby providing some of the properties and advantages of the array.

[0092] To design the array architecture of the OPA 604 (including the placement of the array elements 502 and the nano-antennas 504), a genetic optimization algorithm can be used to search for an array layout or architecture that provides the OPA 604 with the desired specifications. To generate the desired specifications, the algorithm can define a set of constraints, such as a constraint to space the antenna elements more than ½ wavelength apart, a constraint defining a desired average sidelobe level as a threshold, a constraint defining a desired peak sidelobe level as a threshold, a constraint defining a desired peak-to-sidelobe ratio (e.g., the intensity of the peak of the optical signal beam compared to the sidelobe intensity in a ratio form) as a threshold. For example, the maximum sidelobe peak for the main beam can be constrained to be not allowed to exceed −16 dB near the main beam and −10 dB at the edge of the field of view of the optical signal beam. Further constraints can include beam width, power consumption, or any other constraints the designer desires.

[0093] A genetic algorithm is an algorithm for solving both constrained and unconstrained optimization problems that is based on natural selection. A genetic algorithm iteratively modifies a population of individual solutions. At each step, the genetic algorithm selects individual solutions from the current population of solutions to be "parents" and uses them to generate the "children" of the next generation. With each generation, the population "evolves" towards an optimal solution. Genetic algorithms can be applied to solve a wide variety of optimization problems that are not well suited to standard optimization algorithms, such as problems where the objective function is discontinuous, non-differentiable, stochastic, or highly nonlinear.

[0094] For example, when determining the positioning of array elements in a pseudorandom sparse array of nanophotonic antennas, the problem can be mapped to a grid with possible placement locations at the nodes of the grid. The grid can include a larger number of nodes at intersections in the grid than the number of array elements used in the OPA being designed. Each node can be either a filled node where an array element is present or an empty node where no array element is present. Modeling of the light beam and array properties can be used to determine the operating characteristics of the light beam and array. Each defined constraint can then be monitored using various solutions of array element placement to see if a particular solution meets the desired design constraints. Solution iterations can then be performed to find a best-fit solution for the placement of array elements that meets the defined constraints.

[0095] In other words, a genetic algorithm for designing the placement of array elements 502 can start with a randomly generated set of possible solutions and work towards an optimal or acceptable solution for the placement of array elements and nanoantennas. All constraints can be encoded in DNA, a sequence of binary values ​​that uniquely represents a possible solution for the placement of array elements in the OPA. Initially, the genetic algorithm generates a set of random solutions as a first generation of solutions. The first generation of solutions can first be evaluated for fitness based on how well the solutions match the design criteria. Then, the most fit solutions according to the optimization criteria (e.g., the defined constraints) are kept in the society and the other solutions are removed from the society (similar to natural selection). Through iterations of crossing over possible solutions remaining in the society after natural selection, the next generation of the society of solutions can be generated using a pair of parent solutions for each new member of the society of solutions ("child"). The child solutions can be further "mutated" by randomly flipping certain bits of the solutions to generate new solutions that are considered in future iterations. In subsequent iterations, the fitness of new solutions can be evaluated based on calculating how well each solution fits the design constraints. Then, the process of natural selection, parent selection, offspring generation, mutation, and further iterations can be performed. As this process is repeated, the social solution evolves and approaches a global optimum and / or acceptable solution for the placement of antenna elements to achieve the design goal. Genetic algorithms are well suited for sparse array design on grids because the ability to represent the presence or absence of each element at the nodes of the grid with a single bit (1 if the element is present and 0 if the element is not present) reduces the length of DNA, and allows for fast exploration and thorough search of multiple possible solutions.

[0096] Exemplary design constraints may include the peak-to-sidelobe ratio of the optical signal beam emitted by the array, the spacing in excess of half a wavelength between array elements, the maximum dimension of the array elements 502, the maximum unit cell size, the maximum array grid spacing, and the maximum mean error radius (CEP) of the phase center position at different scan angles.

[0097] When designing the pseudorandom sparse array of the present disclosure, the solution may be determined considering multiple scan angles of the optical signal beam, not just the peak-to-sidelobe ratio for one emission of the optical signal beam. For example, the OPA 604 of the present disclosure is for emission of an optical signal beam that is steerable in two dimensions. The optical signal beam is intended to be steerable over a range of scan angles including multiple different scan angles (e.g., the beam may be steerable over a range of scan angles from +60 degrees to -60 degrees). While one solution of the genetic algorithm may meet the peak-to-sidelobe ratio criteria for one scan angle, one skilled in the art will understand that steering the beam to other angles will affect the strength of the sidelobes, such that the sidelobes can be large at certain scan angles of the optical signal beam and suppressed at other scan angles of the optical signal beam. Thus, in accordance with the principles of the present disclosure, the placement of array elements 502 within OPA 604 can be determined using a genetic algorithm to determine the peak-to-sidelobe ratio of the optical signal beam at each of a number of scan angles of the optical signal beam (e.g., −60, −59, −58, ... 58, 59, 60 degrees, etc.).

[0098] By calculating the peak-to-sidelobe ratio at multiple scan angles of the optical signal beam, the arrangement of the array elements 502 of the OPA 604 can be determined to provide a pseudo-random sparse array with the following properties: The non-periodic positions of the array elements in the optical phased array (OPA) are set at pseudo-random positions such that the emitted optical signal beam from the multiple array elements has a peak-to-sidelobe ratio greater than a predetermined threshold (e.g., a desired value set as a design constraint in a genetic algorithm) at each of multiple scan angles of the emitted optical beam.

[0099] Additionally, the pseudo-random positions of the array elements can be set so that the emitted optical signal beams from the plurality of array elements have a peak-to-sidelobe ratio greater than a predetermined threshold at each of a plurality of scan angles between −60 degrees and +60 degrees, or any other range of scan angles desired by the array designer.

[0100] The pseudo-random positions of the array elements are set such that the emitted optical signal beam is continuously steerable through multiple scan angles by control of the phase adjustments made by one or more of the optical phase modulators. In this disclosure, "continuously steerable" is intended to mean that there are no intermediate indeterminate states between the multiple scan angles.

[0101] Furthermore, the array may be designed such that, even with a single coherent wavelength of electromagnetic radiation provided by the electromagnetic radiation source, the pseudo-random positions of the array elements are set such that the emitted optical signal beam from the multiple array elements can be continuously steered in two dimensions over multiple scan angles by only controlling the phase adjustments made by one or more of the optical phase modulators. For example, the laser 602 (e.g., optical energy source laser 608) may be configured to emit electromagnetic radiation of a single coherent wavelength. In many common beam steering arrays, steering is performed by scanning the source laser over different wavelengths of light. However, scanning over different wavelengths may result in large side lobes that may interfere with the main optical signal beam, as well as fluctuations in the received wavelength in the receive mode of the incident radiation. However, the principles of the present disclosure allow the arrangement of the array elements in the OPA to be designed and configured to allow full scanning over multiple angular ranges without changing the wavelength of the laser source light by maintaining the wavelength of the laser light at a single coherent wavelength and steering the beam using only phase adjustments. In other words, there is no need to scan across different wavelengths of electromagnetic radiation to steer the beam, and beam steering can be achieved by manipulating the phase modulators alone. Furthermore, with the pseudorandom sparse array architecture described herein and the large number of emitters 502 inherent in the optical array, beam steering is possible using only 2-bit or 1-bit phase adjustments applied by the optical phase modulators of the array elements. For example, when the number of array elements that can be manipulated to steer the beam is large, the phase shift values ​​applied by each modulator need only be 0 or π to properly steer the beam.

[0102] Any other design criteria and constraints can be used to determine the placement of array elements 502 within OPA 604. For example, the beam width of the optical signal beam can be constrained to a desired width. Rather than a range of scan angles for the optical signal beam, the genetic algorithm solution can be iterated to satisfy the design criteria and constraints no matter where the beam is steered over a range of scan angles.

[0103] Due to the side lobe suppression achieved by the pseudo-random sparse array design described herein, the PIC 402 may be scalable to any size, limited only by practical packaging constraints. Because side lobe suppression is achieved by pseudo-random placement of the array elements 502 (e.g., the PIC unit cells of the photonic integrated circuit 402), the unit cells and the PIC 402 as a whole are no longer limited to maintaining a spacing between unit cells of a half wavelength of electromagnetic radiation. Side lobes can be suppressed at spacings greater than a half wavelength. This therefore facilitates scalability of the OPAs, PICs, and unit cells of the array elements described herein without risk of optical beam signal degradation. In other words, the deterministic placement of the array elements 502 by the genetic algorithm may suppress side lobes in an optical array at any desired size, e.g., in the case of a sparse array, allowing the baseline dimension of the array to be decoupled from the number of emitters. This scalability also allows for the accommodation of optical and electrical routing with margins without risk of routing interference or overlap.

[0104] An example illustrating the side lobe suppression achieved by the principles described herein is shown in FIG. 12. Plot (A) of FIG. 12 shows a simulation of the angular power distribution from a 1024×1024 pseudorandom sparse array (RSA) design in accordance with the principles described herein. Plot (B) is a zoomed-in view of the central 0.6×0.6 degree portion of plot (A). Beam 902 is too narrow to be fully seen in plot (A) but is shown in plot (B). As can be seen in plot (A), plot (A) does not show any side lobes of significant intensity. Additionally, the zoomed-in view of plot (B) also does not show any significant side lobes. A narrow and well-defined main lobe of optical signal beam 902 is shown with a narrow width.

[0105] FIG. 13 illustrates electrical connections between the phase modulator 508 of the array element 502 and the electronic layer 510 (e.g., DRIIC layer 510) of the photonic integrated circuit 402. The array element 502 may be part of an array of OPAs 604 of a plurality of array elements 502. The OPAs 604, array elements 502, and waveguides 700 may constitute a photonic layer of the photonic integrated circuit 402. The photonic layer (including the OPAs 604, array elements 502, and waveguides 700) may be supported by a substrate 603. Various electrical connections may be provided within or with the DRIIC layer 510, as described elsewhere in this disclosure. The DRIIC layer may include CMOS electronics, or any other electronics suitable for controlling the phase modulator 508. The DRIIC layer 510 may also be referred to as the electronic layer 510. The DRIIC layer 510 may be disposed on a surface of the photonic layer (e.g., OPAs 604). The DRIIC 510 may include a circuit board in electrical communication with each of the optical phase modulators 508 of the array elements 502. The digital readout integrated circuit may be configured to apply voltages to control each of the optical phase modulators 508. Each of the optical phase modulators 508 may be electrically connected to the DRIIC layer 510 by one or more vias (e.g., through silicon vias or TSVs) formed through the substrate 603.

[0106] It will be appreciated that in an alternative arrangement, on-chip electronics may be disposed on the substrate 603 and in electrical communication with the optical phase modulators 508 of each of the plurality of array elements 502. The on-chip electronics may be configured to apply a voltage to each of the optical phase modulators 508 to modulate an optical signal beam in a segment 506 of a waveguide that communicates with the optical antenna 504.

[0107] Alternative waveguide routing structures are also within the scope of this disclosure to direct electromagnetic (light) energy from a source laser (e.g., laser 602) to the array elements 502' and 502" shown in Figures 14 and 15. Figures 14 and 15 show an H-tree structure of waveguides for directing electromagnetic radiation to the array elements 502' and 502" in their respective OPA sections 638' and 638". As shown in Figure 14, OPA section 638' can include a waveguide 702' with an input 701' for receiving electromagnetic radiation. Waveguide 702' can include: It may include a series of branches (including branches 703', 704', 705', and 706') that split the waveguide 702' into two approximately equal portions at multiple locations along the waveguide 702'. Branch 706' splits the waveguide into two segments (e.g., segment 506'), each of which feeds an array element 502' that faces outward from the other array element 502'. Array element 502' may include segment 506', optical phase modulator 508', and antenna element 504'. This architecture may be equally used in a receive mode.

[0108] Similarly, as shown in FIG. 15, OPA section 638″ can include a waveguide 702″ with an input 701″ therein for receiving electromagnetic radiation. Waveguide 702″ can include a series of branches (including branches 703″, 704″, 705″, and 706″) that split the waveguide 702″ into two approximately equal portions at multiple locations along the waveguide 702″. Branch 706″ splits the waveguide into two segments (e.g., segment 506″), with each segment feeding an array element 502″ that faces towards the other array element 502″. Array element 502″ can include segment 506″, optical phase modulator 508″, and antenna element 504″.

[0109] 14 and 15 show antenna elements 504' and 504" at equal distances from one another, it should be understood that the same pseudo-random spacing of array elements shown in FIG. 7 can be applied to array elements 502' and 502" shown in FIGS. 14 and 15 to achieve the same design objectives for portions 638' and 638" of portion 638. Other routings of waveguides, such as cascade trees or other arrangements, are intended to be within the scope of this disclosure.

[0110] Further contemplated in the present disclosure is a method 1000 of configuring a photonic integrated circuit (PIC). The method is illustrated in FIG. 16. The method may include step 1002 of configuring the photonic integrated circuit (PIC) to include a substrate. The method may further include step 1004 of configuring the photonic integrated circuit (PIC) to include a waveguide at least partially supported by the substrate. The waveguide may be in communication with at least one of an electromagnetic radiation source (i.e., an optical energy source) and a receiver, and the waveguide may be configured to facilitate propagation of an optical signal beam. The method may further include step 1006 of configuring the photonic integrated circuit (PIC) to include an optical phased array (OPA) having a plurality of array elements. Each of the plurality of array elements may include an optical antenna and an optical phase modulator associated with the optical antenna. The optical phase modulator is operable to modulate an optical signal beam in a segment of the waveguide in communication with the optical antenna. The method may further include step 1008, in which the locations of at least some of the plurality of array elements are non-periodic in one or more directions on the substrate.

[0111] The method may further include determining positions of the plurality of array elements at non-periodic positions based on a solution from a genetic algorithm described herein. The method may further include positioning array elements at non-periodic positions within an optical phased array (OPA) such that an emitted optical signal beam from the plurality of array elements has a peak-to-sidelobe ratio that exceeds a predetermined threshold, the peak-to-sidelobe ratio comprising a ratio of peak beam intensity to grating lobe intensity in the emitted beam.

[0112] The method may further include positioning array elements within the optical phased array (OPA) in non-periodic positions such that an emitted optical signal beam from the plurality of array elements has a peak-to-sidelobe ratio that exceeds a predetermined threshold at each of a plurality of scan angles of the emitted optical beam. The method may further include positioning array elements within the optical phased array (OPA) in non-periodic positions such that an emitted optical signal beam from the plurality of array elements has a peak-to-sidelobe ratio that exceeds a predetermined threshold at each of a plurality of scan angles between −60 degrees and +60 degrees. The method may further include positioning array elements within the optical phased array (OPA) in non-periodic positions such that an emitted optical signal beam is continuously steerable across a plurality of scan angles by control of phase adjustments provided by one or more of the optical phase modulators.

[0113] The method may further include positioning the array elements within non-periodic positions within the OPA such that emitted optical signal beams from the plurality of array elements are steerable continuously across a plurality of scan angles by control of phase adjustments provided by one or more of the optical phase modulators with electromagnetic radiation of a single coherent wavelength provided by the electromagnetic radiation source. The method may further include positioning the array elements within non-periodic positions within the OPA such that emitted optical signal beams from the plurality of array elements are steerable in two dimensions by control of phase adjustments provided by one or more of the optical phase modulators.

[0114] The method can further include positioning the array elements at non-periodic positions within an optical phased array (OPA) such that the array elements are spaced apart from one another by more than half a wavelength relative to a wavelength of electromagnetic radiation provided by the laser source.

[0115] Reference has been made to the examples illustrated in the drawings, and specific language has been used herein to describe these. It will be understood, however, that no limitation of the scope of the technology is intended thereby. Modifications and further variations of the features illustrated herein, as well as further applications of the examples illustrated herein, should be considered within the scope of the description.

[0116] Although the present disclosure may not expressly disclose that some embodiments or features described herein may be combined with other embodiments or features described herein, the present disclosure should be read to describe any such combinations that may be performed by one of ordinary skill in the art. The use of "or" in this disclosure should be understood to mean a non-exclusive or, i.e., "and / or," unless otherwise indicated herein.

[0117] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more examples. In the foregoing description, numerous specific details, such as examples of various configurations, have been provided to provide a thorough understanding of examples of the described technology. However, it will be understood that the technology can be practiced without one or more of the specific details, or with other methods, components, devices, etc. In other instances, well-known structures or operations have not been shown or described in detail to avoid obscuring aspects of the technology.

[0118] Although the subject matter has been described in language specific to structural features and / or operations, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features and operations described above. Rather, the specific features and operations described above are disclosed as example forms of implementing the claims. Numerous modifications and alternative arrangements may be devised without departing from the spirit and scope of the described technology.

Claims

1. A substrate; a waveguide at least partially supported by the substrate, the waveguide being in communication with at least one of an electromagnetic radiation source and a receiver and configured to facilitate propagation of an optical signal beam; 1. An optical phased array (OPA) comprising a plurality of array elements, each of the plurality of array elements comprising: Optical antenna, and an optical phase modulator associated with the optical antenna and operable to modulate the optical signal beam in a segment of the waveguide in communication with the optical antenna; an optical phased array having Including, at least some of the array elements of the plurality of array elements are optically coupled to the waveguide at non-periodic positions on the substrate; Photonic Integrated Circuits (PICs).

2. 2. The photonic integrated circuit (PIC) of claim 1, wherein the optical phased array is a sparse array in which a plurality of array elements are positioned such that a distance between the array elements is greater than ½ a wavelength of electromagnetic radiation from the electromagnetic radiation source.

3. the non-periodic positions of the array elements in the optical phased array (OPA) are set such that an emitted optical signal beam or a received beam gain envelope from the plurality of array elements has a peak-to-sidelobe ratio greater than a predetermined threshold; The photonic integrated circuit (PIC) of claim 1 , wherein the peak-to-sidelobe ratio comprises a ratio of peak beam intensity / gain to grating lobe intensity / gain in the radiation beam.

4. 4. The photonic integrated circuit (PIC) of claim 3, wherein the non-periodic positions of the array elements in the optical phased array (OPA) are pseudo-random positions set such that an emitted optical signal beam, or a receive beam gain envelope from the plurality of array elements, has a peak-to-sidelobe ratio greater than a predetermined threshold at each of a plurality of scan angles of the emitted optical beam.

5. the plurality of scan angles of the emitted light beam or the receive beam gain envelope have angles between −60 degrees and +60 degrees; 5. The photonic integrated circuit (PIC) of claim 4, wherein the pseudo-random positions of the array elements are set such that the emitted optical signal beams or the received beam gain envelopes from the plurality of array elements have a peak-to-sidelobe ratio greater than a predetermined threshold at each of the plurality of scan angles between −60 degrees and +60 degrees.

6. 4. The photonic integrated circuit (PIC) of claim 3, wherein the pseudo-random positions of the array elements are set such that the emitted optical signal beam or the received beam gain envelope is continuously steerable across the multiple scan angles by control of phase adjustments provided by one or more of the optical phase modulators.

7. 7. The photonic integrated circuit (PIC) of claim 6, wherein the pseudo-random positions of the array elements are set such that the emitted optical signal beams or the received beam gain envelope from the multiple array elements are continuously steerable across the multiple scan angles by control of the phase adjustments provided by one or more of the optical phase modulators using electromagnetic radiation of a single coherent wavelength provided by the electromagnetic radiation source.

8. 7. The photonic integrated circuit (PIC) of claim 6, wherein the pseudo-random positions of the array elements are set such that the emitted optical signal beam or the received beam gain envelope from the plurality of array elements is steerable in two dimensions by control of the phase adjustments provided by one or more of the optical phase modulators.

9. The photonic integrated circuit (PIC) of claim 1 , wherein the locations of at least some of said plurality of array elements are non-periodic in one or more directions on said substrate.

10. a source laser as the electromagnetic radiation source configured to generate optical energy, the antenna element configured to transmit the optical signal beam based on the optical energy; and a receiver configured to receive and process the optical signal beam received by the antenna element; The photonic integrated circuit (PIC) of claim 1 further comprising at least one of:

11. The photonic integrated circuit (PIC) of claim 10 , wherein said source laser generates optical energy at a single coherent wavelength.

12. The photonic integrated circuit (PIC) of claim 1 , wherein the waveguide is an optical waveguide.

13. 2. The photonic integrated circuit (PIC) of claim 1, comprising on-chip electronic circuitry disposed on the substrate and in electrical communication with the optical phase modulator of each of the plurality of array elements, the on-chip electronic circuitry configured to apply a voltage to each of the optical phase modulators to modulate the optical signal beam in a segment of the waveguide in communication with the optical antenna.

14. It includes multiple layers, The plurality of layers include a photonic layer including the optical phased array (OPA) and the waveguide; an electronics layer including a digital read-out integrated circuit (DRIIC) in electrical communication with each of the optical phase modulators of the array elements, the DRIIC configured to apply a voltage to control each of the optical phase modulators; Including, The photonic integrated circuit (PIC) of claim 1.

15. The photonic integrated circuit (PIC) of claim 14 , wherein the electronic layer comprises one or more CMOS circuits.

16. A source of electromagnetic radiation, and Photonic Integrated Circuits (PICs), A photonic integrated system comprising: The photonic integrated circuit comprises: A substrate; a waveguide at least partially supported by the substrate, the waveguide being in communication with at least one of an electromagnetic radiation source and a receiver and configured to facilitate propagation of an optical signal beam; 1. An optical phased array (OPA) comprising a plurality of array elements, each of the plurality of array elements comprising: Optical antenna, and an optical phase modulator associated with the optical antenna and operable to modulate the optical signal beam in a segment of the waveguide in communication with the optical antenna; an optical phased array having Including, at least some of the array elements of the plurality of array elements are optically coupled to the waveguide at non-periodic positions on the substrate; Photonic integrated systems.

17. 17. The photonic integrated system of claim 16, wherein the optical phased array is a sparse array in which the array elements are positioned such that a distance between the array elements is greater than ½ of a wavelength of electromagnetic radiation from the electromagnetic radiation source.

18. the non-periodic positions of the array elements in the optical phased array (OPA) are set such that an emitted optical signal beam or a received beam gain envelope from the plurality of array elements has a peak-to-sidelobe ratio greater than a predetermined threshold; 17. The photonic integrated system of claim 16, wherein the peak-to-sidelobe ratio comprises a ratio of peak beam intensity to grating lobe intensity in the emitted beam or the received beam gain envelope.

19. 20. The photonic integrated system of claim 18, wherein the non-periodic positions of the array elements in the optical phased array (OPA) are pseudo-random positions set such that an emitted optical signal beam or a received beam gain envelope from the plurality of array elements has a peak-to-sidelobe ratio greater than a predetermined threshold at each of a plurality of scan angles of the emitted optical beam or the received beam gain envelope.

20. 1. A method of constructing a photonic integrated circuit (PIC), comprising: Configuring the photonic integrated circuit (PIC) to include a substrate; configuring the photonic integrated circuit (PIC) to include a waveguide at least partially supported by the substrate, the waveguide in communication with at least one of an electromagnetic radiation source and a receiver, the waveguide configured to facilitate propagation of an optical signal beam; Configuring the photonic integrated circuit (PIC) to include an optical phased array (OPA) having a plurality of array elements, each of the plurality of array elements comprising: Optical antenna, and an optical phase modulator associated with the optical antenna and operable to modulate the optical signal beam in a segment of the waveguide in communication with the optical antenna; and configuring at least some of the array elements of the plurality of array elements to be optically coupled to the waveguide, wherein positions of at least some of the array elements of the plurality of array elements are non-periodic in one or more directions on the substrate; The method includes:

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