Integrated on-chip wireless optical communication terminal

Abstract

To provide a system architecture for a wireless optical communication terminal that can be integrated on one or more photonic integrated chips.SOLUTION: The free-space optical communication system includes an optical phased array (OPA) photonic integrated chip (114), a transceiver photonic integrated chip (112), and one or more processors (104). The OPA chip includes a plurality of array elements (120) and a plurality of phase shifters (121). The transceiver chip includes one or more transmitter components 116 and one or more receiver components 118. The one or more processors are configured to transmit 402 a first signal via the OPA chip and the transceiver chip, and receive 410 a second signal via the OPA chip and the transceiver chip.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to and benefit of the filing dates of U.S. Patent Application No. 17 / 890,378, filed August 18, 2022, and U.S. Provisional Patent Application No. 63 / 246,599, filed September 21, 2021, the entire disclosures of which are incorporated herein by reference. [Background technology]

[0002] Wireless optical communications enable high-throughput and long-distance communications, in part due to the high gain provided by the narrow angular width of the transmitted beam. However, the narrow beam also requires that it must be accurately and actively pointed to remain aligned with the terminal aperture at the remote end. This pointing can be achieved by small mirrors (e.g., MEMS or voice coil-based fast steering mirror mechanisms) that are actuated to steer the beam. In other implementations, electro-optical steering of the beam with no moving parts is used to steer the beam, which offers cost, lifetime, and performance advantages. Optical phased arrays (OPAs) are a key technology building block with additional advantages for adaptive optics, point-to-multipoint support, and mesh network topologies. Each active element within an OPA requires electro-optical phase shifting capabilities. Summary of the Invention

[0003] Aspects of the present disclosure provide a free-space optical communication system that includes an optical phased array (OPA) chip having a plurality of array elements and a plurality of phase shifters, a transceiver chip having one or more transmitter components and one or more receiver components, and one or more processors configured to transmit a first signal via the OPA chip and the transceiver chip and receive a second signal via the OPA chip and the transceiver chip.

[0004] In one example, the system also includes a plurality of lenses forming a telescope that captures light from free space and transmits light from the OPA chip. In another example, the system also includes a single-mode circulator and a single-mode waveguide connecting the OPA chip and the single-mode circulator. In a further example, the one or more transmitter components include a seed laser. In yet another example, the one or more receiver components include a sensor. In this example, the one or more receiver components also include an attenuator and an amplifier.

[0005] In yet a further example, the system also includes an amplifier that increases the gain of the first signal between the transceiver chip and the OPA chip. In another example, the system also includes a steering mirror, and the one or more processors are also configured to control the steering mirror to adjust the wavefronts or pointing directions of the first and second signals.

[0006] Another aspect of the present disclosure provides a method for performing wavefront correction for optical communications, the method including receiving a first optical communications beam at an optical phased array on a photonic integrated chip in a communications system, measuring, by one or more processors of the communications system, a phase front of the first optical communications beam at a plurality of phase shifters on the photonic integrated chip, determining, by the one or more processors, a wavefront error of the first optical communications beam based on the measured phase front, adjusting, by the one or more processors, a wavefront or pointing direction of the communications system based on the determined wavefront error, and transmitting, by the one or more processors, a second optical communications beam using the photonic integrated chip and the adjusted wavefront or pointing direction.

[0007] In one example, measuring the phase front includes detecting phase shift settings in multiple phase shifters. In another example, determining the wavefront error includes determining a tip term and a tilt term. In a further example, adjusting the wavefront or pointing direction includes mechanical steering of a mirror. In yet another example, adjusting the wavefront or pointing direction includes electronic steering using multiple phase shifters. In yet another example, adjusting the wavefront or pointing direction includes controlling a secondary steering element for larger, low-frequency adjustments and a photonic integrated chip for smaller, high-frequency adjustments.

[0008] In another example, a first set of processors of the one or more processors performs the phase front measurement, wavefront error determination, and wavefront or pointing direction adjustment, and a second set of processors of the one or more processors performs the transmission of the second optical communications beam. In this example, the phase front measurement, wavefront error determination, and wavefront or pointing direction adjustment comprise a feedback loop. Further in this example, the method also includes tracking changes in the first optical communications beam using the feedback loop. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram 100 of a first communication device and a second communication device according to an aspect of the disclosure. [Figure 2] 2 is a pictorial diagram 200 of an example system architecture for the first communication device of FIG. 1 according to an aspect of the disclosure. [Figure 3] FIG. 1 is a pictorial diagram of a network according to an aspect of the present disclosure. [Figure 4] FIG. 1 is a flow diagram according to an aspect of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] overview The present technology relates to a system architecture for wireless optical communication terminals that may be integrated onto one or more photonic integrated chips. The system architecture may be configured to combine and streamline multiple functions and leverage innovations in pointing / beam steering, acquisition, and tracking. For example, a chip may be used for both the positioning and communication functions, which eliminates any boresight error from separate positioning or tracking architectures. The system architecture may include a photonic integrated transceiver and a software-defined optical modem.

[0011] The system architecture can include an optical phased array (OPA) photonic integrated circuit or chip designed to provide wavefront correction of an incident beam. In particular, the OPA chip can be designed with an OPA having a sufficiently high element count and density to provide sufficiently high spatial resolution for providing wavefront correction. The OPA chip can include multiple phase shifters configured to control signals received by and transmitted from the OPA array elements. The OPA chip can also include a single-path fully reciprocal optical design connected to a single transceiver component for receiving and transmitting the optical beam.

[0012] A secondary steering element can be included in the system to further adjust the angle of arrival of the incident beam to better position it with the terminal sensor or optical fiber. The secondary steering element can be a steering mirror, such as a fast steering / pointing mirror, or other type of steerable element controlled by an actuator. Alternatively, the secondary steering element can be a liquid crystal, a spatial light modulator, or other type of signal modulation means.

[0013] One or more processors in the system may use the OPA to determine the angle of arrival of the incident beam. For example, the phase front of the incident beam can be measured and extracted based on the beam portion received at each array element of the OPA and the spatial resolution of the entire OPA. That is, the phase shift settings of multiple phase shifters relative to the incident beam can be extracted and used to calculate the wavefront error and corresponding wavefront correction. The wavefront error can include tip and tilt terms (e.g., terms for the estimated angle of arrival) as well as higher-order terms related to other variations in the beam. The beam variations can be caused by environmental disturbances, atmospheric turbulence, or other external factors.

[0014] The one or more processors may cause mechanical or electronic steering based on the calculated wavefront correction. For example, the one or more processors may control a secondary steering element, an OPA, or both to perform the wavefront correction. In a hybrid tracking configuration, the secondary steering element may be controlled for larger and / or lower frequency adjustments, and the OPA may be controlled for smaller and / or higher frequency adjustments. Once wavefront correction is performed on the incident beam, the single transmit / receive design of this system architecture essentially performs pre-correction waveform distortion of the transmit beam from the terminal based on the same correction. The reciprocity of beam propagation in atmospheric turbulence ensures that pre-distortion based on the locally received correction maximizes power coupling in opposite directions across the communication link.

[0015] The system architecture may also include an on-chip single-mode transceiver that fully integrates photonics with traditionally discrete components. For example, photonics components such as filters, multiplexers, demultiplexers, photodetectors, optical amplifiers, variable optical attenuators, and electronic circuits may be integrated onto a single chip. The transceiver chip is configured to receive and process optical beams received and transmitted by the terminal. In some implementations, the transceiver chip may be integrated as part of the OPA chip.

[0016] Overall, this design also enables a low-cost system that can still operate at sensitivities and data rates previously achievable only with systems using expensive adaptive optics to couple to single-mode fiber. The integrated chip design allows for cost reductions associated with sourcing and manufacturing components such as transceiver and filter components. The system architecture also advantageously supports both IM / DD (intensity modulation and direct detection) and coherent (homodyne, heterodyne, intradyne) systems.

[0017] This design allows the system to omit components dedicated to tracking or alignment, such as beacon beams, dedicated optics, or dedicated sensors. Labor-intensive manufacturing and maintenance steps for aligning the tracking / alignment components with the communication link can also be eliminated. Similar omissions can be made in manufacturing and maintenance steps for alignment between the transmit and receive architectures, since they share components and paths.

[0018] Additionally, opto-electrical beam steering using an OPA can be the primary means for alignment and tracking, instead of opto-mechanical beam steering, resulting in fewer moving components and fewer errors. Additionally or alternatively, including a secondary steering element in the system allows for the use of an OPA with a relatively low element count, such as fewer than 1000 elements, which can reduce costs associated with the OPA in manufacturing, power consumption, thermal management, and electrical interfacing, among other things. In some other examples, the OPA may be designed with an element density and number large enough to achieve all steering capabilities, allowing all other steering components to be omitted entirely from the system.

[0019] Overall, this system architecture for an optical communications terminal reduces the number of optical components, assembly tolerances, optical quality requirements, and therefore ultimately reduces the cost of the optical assembly and the wireless optical communications terminal.

[0020] System Example Figure 1 is a block diagram 100 of a first communication device of a first communication terminal configured to form one or more links with a second communication device of a second communication terminal, for example, as part of a system such as a free-space optical communications (FSOC) system. Figure 2 is a pictorial diagram 200 of an example system architecture of the first communication device of Figure 1. For example, the first communication device 102 includes one or more processors 104, memory 106, a transceiver photonic integrated chip 112, and an optical phased array (OPA) photonic integrated chip 114. In some implementations, the first communication device 102 may include two or more transceiver chips and / or two or more OPA chips.

[0021] The one or more processors 104 may be any conventional processor, such as a commercially available CPU. Alternatively, the one or more processors may be dedicated devices, such as application specific integrated circuits (ASICs), or other hardware-based processors, such as field programmable gate arrays (FPGAs). While FIG. 1 functionally depicts the one or more processors 104 and memory 106 as being within the same block, such as modem 202 for digital signal processing shown in FIG. 2, the one or more processors 104 and memory 106 may actually comprise multiple processors and memories that may or may not be housed within the same physical housing, such as both modem 202 and a separate processing unit 203. Thus, reference to a processor or computer will be understood to include reference to a collection of processors or computers or memories that may or may not operate in parallel.

[0022] The memory 106 may store information accessible by one or more processors 104, including data 108 and instructions 110 that may be executed by the one or more processors 104. The memory may be any type of memory capable of storing information accessible by a processor, including computer-readable media such as hard drives, memory cards, ROM, RAM, DVDs, or other optical disks, as well as other writable and read-only memory. Systems and methods may include various combinations of the above, whereby various portions of the data 108 and instructions 110 are stored on various types of media. The memory of each communication device, such as the memory 106, may store calibration information, such as one or more offsets determined for tracking signals.

[0023] Data 108 may be retrieved, stored, or modified by one or more processors 104 according to instructions 110. For example, although the system and method are not limited by any particular data structure, data 108 may be stored in computer registers in a relational database, as a table with multiple distinct fields and records, an XML document, or a flat file. Data 108 may be formatted in any computer-readable format, such as, but not limited to, binary values ​​or Unicode. By way of further example only, image data may be stored as a bitmap, which consists of a grid of pixels stored according to a format that is compressed or uncompressed, lossless (e.g., BMP) or lossy (e.g., JPEG), and bitmap or vector-based (e.g., SVG), as well as computer instructions for drawing graphics. Data 108 may include any information sufficient to identify related information, such as numbers, descriptive text, dedicated codes, references to data stored in other areas of the same or different memory (including other network locations), or information used by a function to calculate related data.

[0024] The instructions 110 may be any set of instructions (e.g., machine code) or instructions (e.g., script) that are executed directly or indirectly by one or more processors 104. For example, the instructions 110 may be stored as computer code on a computer-readable medium. In this regard, the terms “instructions” and “program” may be used interchangeably herein. The instructions 110 may be stored in object code format for direct processing by one or more processors 104, or may be stored in any other computer language, including a script or collection of separate source code modules that are interpreted on demand or pre-compiled. The functions, methods, and routines of the instructions 110 are described in more detail below.

[0025] The one or more processors 104 may be in communication with the transceiver chip 112. As shown in FIG. 2, the one or more processors in the modem 202 may be in communication with the transceiver chip 112 and configured to receive and process incoming optical signals and transmit optical signals. The transceiver chip 112 may include one or more transmitter components and one or more receiver components. Thus, the one or more processors 104 may be configured to transmit data in signals via the transmitter components and may be configured to receive communications and data in signals via the receiver components. The received signals may be processed by the one or more processors 104 to extract the communications and data.

[0026] The transmitter components can include at least a light source such as a seed laser 116. Other transmitter components may include an amplifier such as a high-power semiconductor optical amplifier 204. In some implementations, the amplifier is on a separate photonic chip. The seed laser 116 may be a distributed feedback laser (DFB), a light-emitting diode (LED), a laser diode, a fiber laser, or a solid-state laser. The optical output or optical signal of the seed laser 116 can be controlled by a current or an electrical signal applied directly to the seed laser, such as from a modulator that modulates a received electrical signal. The light transmitted from the seed laser 116 is received by the OPA chip 114.

[0027] The receiver components may include at least a sensor 118, such as a photodiode. The sensor may convert the received light or optical signal into an electrical signal that can be processed by one or more processors. Other receiver components may include an attenuator, such as variable optical attenuator 206, an amplifier, such as semiconductor optical amplifier 208, or a filter.

[0028] The one or more processors 104 may be in communication with an optical phased array chip 114. The OPA chip 114 receives light from a transmitter component and outputs light as a coherent communication beam that is received by a remote communication device, such as a second communication device 122. The OPA chip 114 also receives light from free space, such as a communication beam from the second communication device 122, and provides it to a receiver component.

[0029] The OPA chip 114 may include multiple array elements 120 and multiple phase shifters 121. The multiple array elements 120 may be arranged in a grid pattern with a consistent pitch or distance between adjacent elements. In other examples, the array elements 120 may be arranged differently, with different numbers of rows and columns, different shapes, and / or different pitches (consistent or inconsistent). The phase shifters 121 alter the incoming and outgoing light. The incoming light is provided to the receiver component, and the outgoing light is provided to the array elements 120. The architecture of the multiple phase shifters 121 includes at least one layer of phase shifters, with one phase shifter connected to each array element in the multiple array elements 120. In some examples, the phase shifter architecture includes multiple layers of phase shifters, where the phase shifters in a first layer may be connected in series with one or more phase shifters in a second layer. The OPA chip can provide the necessary photonic processing to couple the incoming light beam to a single-mode waveguide that directs the beam toward the transceiver chip 112. In some implementations, the OPA chip can also generate and provide angle-of-arrival estimates to one or more processors 104, such as a processor in processing unit 203.

[0030] The system may include additional components that support the functionality of the communications terminal. For example, the system may include one or more lenses and / or mirrors forming a telescope. The telescope may receive collimated light and output collimated light. The telescope may include an objective portion, an eyepiece portion, or a relay portion. As shown in FIG. 2 , the system may include an objective lens 210, an eyepiece lens 212, and relay lenses 214 and 216. The system may also include a circulator, such as a single-mode circulator 218, that routes the incoming and outgoing light while keeping them at least partially on separate paths. The system may also include one or more sensors 220 for detecting environmental characteristics and / or measurements of system components. The system may also include one or more steering mechanisms, such as one or more biasing means for controlling one or more phase shifters, which may be part of the OPA chip 114, and / or an actuated / steering mirror 222, such as a fast / fine pointing mirror. In some examples, the actuated mirror may be a MEMS two-axis mirror, a two-axis voice coil mirror, or a piezoelectric two-axis mirror. One or more processors 104, such as those in processing unit 203, may be configured to receive and process signals from one or more sensors 220, transceiver chip 112, and / or OPA chip 114 and control one or more steering mechanisms to adjust the pointing direction and / or wavefront shape, as described in more detail below. The system also includes optical fibers or waveguides connecting the optical components and creating a path between seed laser 116 and OPA chip 114 and between OPA chip 114 and photodiode 118.

[0031] As shown in FIG. 1, the first communication device 102 may output a light beam 20 a directed to the second communication device 122 .

[0032] Similarly, the second communication device 122 includes one or more processors 124, memory 126, a transceiver chip 132, and an OPA chip 134. The one or more processors 124 may be similar to the one or more processors 104 described above. The memory 126 may store information accessible by the one or more processors 124, including data 128 and instructions 130 that may be executed by the processor 124. The memory 126, data 128, and instructions 130 may be configured similar to the memory 106, data 108, and instructions 110 described above. Additionally, the transceiver chip 132 and OPA chip 134 of the second communication device 122 may be similar to the transceiver chip 112 and OPA chip 114. The transceiver chip 132 may include both transmitter and receiver components. The transmitter component may include a light source, such as a seed laser 136 configured similar to the seed laser 116. Other transmitter components may include an amplifier, such as a high-power semiconductor optical amplifier. The receiver components may include a sensor 138 configured similarly to sensor 118. Other receiver components may include an attenuator, such as a variable optical attenuator, an amplifier, such as a semiconductor optical amplifier, or a filter. OPA chip 114 may include a plurality of array elements 140 and a plurality of phase shifters 141, which may be similar to array element 120 and phase shifter 121, respectively. Similar to the additional components described above, additional components may be included to support the functionality of communication device 122. Communication device 122 may have a system architecture that is the same as or similar to the system architecture shown in FIG. 2.

[0033] As shown in FIG. 1, the second communication device 122 can output a light beam 20b directed towards the first communication device 102, which receives the light beam 20b.

[0034] As shown in FIG. 1 , a communication link 22 may be formed between the first communication device 102 and the second communication device 122 when the transceivers of the first and second communication devices are aligned. Alignment may be determined by determining when a line of sight is established between the communication devices 102, 122 using optical beams 20 a, 20 b. Using the communication link 22, one or more processors 104 may transmit communication signals to the second communication device 122 through free space using optical beam 20 a, and one or more processors 124 may transmit communication signals to the first communication device 102 through free space using optical beam 20 b. The communication link 22 between the first communication device 102 and the second communication device 122 allows for bidirectional transmission of data between the two devices. Notably, the communication link 22 in these examples may be a free-space optical communication (FSOC) link. In other implementations, one or more of the communication links 22 may be radio frequency communication links or other types of communication links capable of traveling through free space.

[0035] As shown in FIG. 3, multiple communication devices, such as a first communication device 102 and a second communication device 122, can be configured to form multiple communication links (shown as arrows) between multiple communication terminals, thereby forming a network 300. The network 300 can include client devices 310 and 312, a server device 314, and communication devices 102, 122, 320, 322, and 324. Each of the client devices 310, 312, the server device 314, and the communication devices 320, 322, and 324 can include one or more processors, memory, transceiver chips, and OPA chips similar to those described above. Using transmitters and receivers, each communication device in the network 300 can form at least one communication link with another communication device, as shown by the arrows. The communication link can be for optical frequencies, radio frequencies, other frequencies, or a combination of different frequency bands. In FIG. 3, the communication device 102 is shown having communication links with the client device 310 and the communication devices 122, 320, and 322. Communication device 122 is shown having communication links with communication devices 102 , 320 , 322 , and 324 .

[0036] The network 300 shown in FIG. 3 is merely exemplary, and in some implementations, the network 300 may include additional or different communication terminals. The network 300 may be a terrestrial network with multiple communication devices on multiple terrestrial communication terminals. In other implementations, the network 300 may include one or more high altitude platforms (HAPs), which may be balloons, blimps, or other airships, airplanes, unmanned aerial vehicles (UAVs), satellites, or any other form of high altitude platform or other type of mobile or fixed communication terminal. In some implementations, the network 300 may serve as an access network for client devices, such as mobile phones, laptop computers, desktop computers, wearable devices, or tablet computers. The network 300 may also be connected to a larger network, such as the Internet, and may be configured to provide client devices with access to resources stored on or provided through the larger computer network.

[0037] Example of how to During operation, the one or more processors 104 can perform wavefront correction for optical communications. Figure 4 illustrates a flow diagram 400 according to some of the aspects described above, which may be performed by one or more processors 104 of the first communication device 102. Additionally or alternatively, one or more processors 124 of the second communication device 122 may perform one or more steps of the flow diagram 400. While Figure 4 illustrates blocks in a particular order, the order may be changed, multiple operations may be performed simultaneously, and operations may be added or omitted.

[0038] In block 402, a first optical communication beam may be received at an optical phased array on a photonic integrated chip in a communication system. The first optical communication beam may carry data from a remote communication system or a client device. The first optical communication beam may be received at multiple array elements of the optical phased array. Each beam portion received at a given array element may be directed through at least one phase shifter. The beam portions are coupled to a waveguide, which directs the collected beam portions to a receiver component of the communication system for processing. The data may be processed and / or transmitted to the next hop in the network. For example, optical beam 20b may be received at an optical phased array in the OPA chip 114 of the communication device 102. Optical beam 20b may be directed and coupled through a phase shifter 121 in the OPA chip 114 to a single-mode waveguide, which directs the optical beam to a receiver component, such as a sensor 118.

[0039] In block 404, one or more processors of the communication system may measure the phase front of the first optical communication beam at multiple phase shifters on the photonic integrated chip. A phase shift setting may be detected for each phase shifter, and the setting may be used to determine the phase front. For example, one or more processors 104 of the communication device 102 may measure the phase front of the optical beam 20b based on signals received from multiple phase shifters 121.

[0040] In block 406, the one or more processors may determine a wavefront error of the first optical communication beam based on the measured phase front. Determining the wavefront error may include determining terms related to the angle of arrival of the wavefront of the optical beam. These terms may include tip, tilt, or a combination of higher order terms. For example, the one or more processors 104 may determine the wavefront error of the optical beam 20b based on the measured phase front.

[0041] In block 408, the one or more processors may adjust a wavefront or pointing direction of the communication system based on the determined wavefront error. The wavefront and / or pointing direction may be adjusted using mechanical steering, electronic steering, or a combination of both. Mechanical steering may include controlling the angle of a secondary steering element, such as an actuated mirror. Electronic steering may include controlling multiple phase shifters, such as by setting a phase shift setting for each phase shifter. In some implementations, steering a secondary steering element may be used for larger low-frequency adjustments, while steering using multiple phase shifters may be for smaller high-frequency adjustments. For example, the one or more processors 104 may adjust the wavefront and / or pointing direction of the communication device 102 based on the determined wavefront error. Mechanical steering may include controlling the steering mirror 222. Electronic steering may include controlling multiple phase shifters 121.

[0042] In block 410, one or more processors may transmit a second optical communication beam using the photonic integrated chip and the adjusted wavefront and / or pointing direction. For example, the one or more processors 104 may transmit optical beam 20a using array elements 120 and phase shifter 121 of OPA chip 114 and the adjusted pointing direction. Pre-distortion of the wavefront and pointing direction based on the locally received corrections may enable maximizing power coupling in opposite directions across the communication link due to the reciprocity of beam propagation through the atmosphere.

[0043] In some implementations, a first set of processors of the one or more processors performs the phase front measurement, wavefront error determination, and pointing direction adjustment, while a second set of processors of the one or more processors performs the transmission of the second optical communications beam. The phase front measurement, wavefront error determination, and pointing direction adjustment may include a feedback loop. Using the feedback loop, changes in the first optical communications beam may be tracked by the one or more processors. The changes may include position changes, such as drift, fading, or scintillation, or other types of changes.

[0044] The features described herein can be implemented on an integrated photonic chip to provide a more cost-effective and accurate communications system. The single-path transmit-receive design of this system-mode system allows for the use of less complex and less expensive components. Furthermore, this design reduces alignment errors between communications devices, as well as between the tracking system and the communications system within each terminal. This design can also reduce errors by replacing the boresight requirement between the tracking beam and the communications beam with a feedback loop connected directly to the communications beam rather than to the branching beam.

[0045] Unless otherwise specified, the foregoing alternatives are not mutually exclusive and can be implemented in various combinations to achieve unique advantages. These and other variations and combinations of the above features can be utilized without departing from the subject matter defined by the claims, and the foregoing description of embodiments should be construed as illustrative, not limiting, of the subject matter defined by the claims. Furthermore, the provision of examples described herein, as well as terms such as "such as," "including," and the like, should not be construed as limiting the subject matter of the claims to any particular examples; rather, these examples are intended to illustrate only one of many possible embodiments. Furthermore, the same reference symbols on different drawings may identify the same or similar elements.

Claims

1. 1. A free space optical communications system, comprising:

1. An optical phased array (OPA) chip, comprising: a plurality of array elements; an optical phased array (OPA) chip including a plurality of phase shifters; 1. A transceiver chip comprising: one or more transmitter components; one or more receiver components; and one or more processors, Transmitting a first signal through the OPA chip and the transceiver chip; one or more processors configured to receive a second signal via the OPA chip and the transceiver chip; A free space optical communication system comprising:

2. The system of claim 1 , further comprising a plurality of lenses forming a telescope that captures light from free space and transmits light from the OPA chip.

3. The system of claim 1 , further comprising: a single-mode circulator; and a single-mode waveguide connecting the OPA chip and the single-mode circulator.

4. The system of claim 1 , wherein the one or more transmitter components include a seed laser.

5. The system of claim 1 , wherein the one or more receiver components include a sensor.

6. The system of claim 5 , wherein the one or more receiving components further include an attenuator and an amplifier.

7. The system of claim 1 , further comprising an amplifier that increases the gain of the first signal between the transceiver chip and the OPA chip.

8. Further provided with a steering mirror, The system of claim 1 , wherein the one or more processors are further configured to control the steering mirrors to adjust a wavefront or pointing direction of the first signal and the second signal.

9. 1. A method for performing wavefront correction for optical communications, the method comprising: receiving a first optical communication beam at an optical phased array on a photonic integrated chip in a communication system; measuring, by one or more processors of the communication system, a phase front of the first optical communication beam at a plurality of phase shifters on the photonic integrated chip; determining, by the one or more processors, a wavefront error of the first optical communications beam based on the measured phase front; adjusting, by the one or more processors, a wavefront or pointing direction of the communication system based on the determined wavefront error; transmitting, by the one or more processors, a second optical communication beam using the photonic integrated chip and the adjusted wavefront or pointing direction; A method comprising:

10. The method of claim 9 , wherein measuring the phase front comprises detecting phase shift settings in the plurality of phase shifters.

11. The method of claim 9 , wherein the determining the wavefront error comprises determining a tip term and a tilt term.

12. The method of claim 9 , wherein the adjustment of the wavefront or pointing direction comprises mechanical steering of a mirror.

13. The method of claim 9 , wherein the adjusting of the wavefront or pointing direction comprises electronic steering using the plurality of phase shifters.

14. said adjusting the wavefront or pointing direction Controlling a secondary steering element for larger scale low frequency adjustment; and controlling the photonic integrated chip for smaller high frequency tuning.

15. a first set of processors of the one or more processors performs the measurement of the phase front, the determination of the wavefront error, and the adjustment of the wavefront or pointing direction; The method of claim 9 , wherein a second set of processors of the one or more processors performs the transmission of the second optical communications beam.

16. 16. The method of claim 15, wherein the measuring of the phase front, the determining of the wavefront error, and the adjusting of the wavefront or pointing direction comprise a feedback loop.

17. 17. The method of claim 16, further comprising using the feedback loop to track changes in the first optical communications beam.

18. 1. A non-transitory computer-readable storage medium having instructions stored thereon that, when executed by one or more processors, perform a method for performing wavefront correction for optical communications, the method comprising: measuring a phase front of a first optical communication beam at a plurality of phase shifters on a photonic integrated chip in a communication system, the first optical communication beam being received at an optical phased array on the photonic integrated chip; determining a wavefront error of the first optical communication beam based on the measured phase front; adjusting a wavefront or pointing direction of the communication system based on the determined wavefront error; transmitting a second optical communication beam using the photonic integrated chip and the adjusted wavefront or pointing direction; A non-transitory computer-readable storage medium implementing a method, comprising:

19. 20. The non-transitory computer-readable medium of claim 18, wherein measuring the phase front comprises detecting phase shift settings in the plurality of phase shifters.

20. 20. The non-transitory computer-readable medium of claim 18, wherein the determining the wavefront error comprises determining a tip term and a tilt term.

21. said adjusting the wavefront or pointing direction Mechanical steering of mirrors, Electronic steering using the plurality of phase shifters; or 20. The non-transitory computer-readable storage medium of claim 18, further comprising: controlling a secondary steering element for larger low-frequency adjustments and controlling the photonic integrated chip for smaller high-frequency adjustments.

Images