Free-space optical communication system with optical phased array telescope

Abstract

Improved systems and methods for optical communications with reduced size, weight, and power consumption are provided. The systems and methods may be utilized between satellites or other distant systems with large relative motion. Such embodiments include utilizing diamagnetically levitated magnetic or other actuators to control the orientation of an optical phased array (OPA) to point the array toward a distant target system. The OPA has reduced size and mass compared to conventional telescopes, reducing the size, weight, and cost of the OPA and associated actuators while providing a comparable beam aperture. The actuators allow the OPA to omit phase shifter elements or include fewer phase shifter elements than previous steerable OPA telescopes, reducing complexity, cost, and power requirements.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 301,435, filed January 20, 2022, the contents of which are incorporated by reference.

[0002] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with Government support under Contract No. N4175619C3028 awarded by the Navy Engineering Logistics Office. The Government has certain rights in this invention. [Background technology]

[0003] Unless otherwise indicated herein, the material described in this section is not prior art to the claims of this application and is not admitted to be prior art by inclusion in this section.

[0004] For space applications, large diameter laser beams are used for long distance light propagation by reducing losses due to diffraction spread of the beam. Since laser sources and detectors are often very small in diameter, large telescopes are typically used to provide adjustment optics and space for beam resizing. These large telescopes also include pointing systems (often two-axis gimbals that rotate the entire assembly) to maintain links to other communication terminals. Thus, in addition to the large space occupied by the telescope and the weight of the optics and mounts, the steering mechanism is even larger to move the entire assembly.

[0005] Current practice generally uses a telescope for beam sizing and a gimbal to hold and point the entire assembly. To provide space for expanding the beam, the telescope is large in size because it has a large volume of "empty space" inside the assembly.

[0006] Regarding the steering mechanism, gimbals are high TRL (technology readiness level) systems that provide a very wide field of view, exceeding a hemisphere, and can reposition the beam fast enough for most applications. Unfortunately, the systems are also large and have components that are not suitable for integration into a CubeSat platform. They also have a coarse pointing, so an auxiliary pointing mechanism (such as a fast steering mirror) is also provided. Other steering mechanisms generally sacrifice steering performance to achieve a small system size and weight. Summary of the Invention

[0007] In a first aspect, a system is provided, the system comprising: (i) an optical phased array comprising a first optical expansion element having at least two emitter gratings and a beam splitter, the at least two emitter gratings configured to receive respective portions of an input optical beam via the beam splitter and emit respective corresponding portions of a composite output optical beam of the optical phased array, the input optical beam having a first aperture smaller than a second aperture of the composite output optical beam, and a relative phase between light emitted from each of the at least two emitter gratings is static; and (ii) a steering actuator mechanically coupled to the optical phased array and configured to adjust an orientation of the optical phased array.

[0008] In a second aspect, a method is provided, the method including: (i) operating a steering actuator to steer an optical phased array towards a target, the steering actuator being mechanically coupled to the optical phased array and configured to adjust an orientation of the optical phased array; (ii) operating a plurality of phase shifters of the optical phased array to control a direction of an output optical beam of the optical phased array in a first direction relative to the optical phased array during a first time period; and (iii) optically transmitting first information to the target during the first time period, wherein optically transmitting the first information to the target during the first time period includes: (a) operating an optical emitter to generate a beam of light encoding the first information; (b) receiving, by the optical phased array as an input light beam, the beam of light generated by the optical emitter while the optical phased array is directed towards the target; (iv) operating the multiple phase shifters to control a direction of the output light beam in a second direction relative to the optical phased array during a second time period, the second direction being different from the first direction; and (v) optically receiving second information from the target during the second time period, where optically receiving the second information from the target during the second time period includes operating an optical detector optically coupled to the optical phased array to detect the second information optically transmitted from the target and received via the optical phased array.

[0009] In a third aspect, there is provided an article of manufacture including a computer readable medium having stored thereon program instructions which, when executed by a computing device, cause the computing device to perform operations to affect the method of the second aspect.

[0010] In a fourth aspect, a system is provided, the system comprising: (i) an optical phased array configured to receive an input optical beam and emit an output optical beam, the input optical beam having a first aperture smaller than a second aperture of the output optical beam; and (ii) a steering actuator coupled to the optical phased array and configured to adjust an orientation of the optical phased array, the steering actuator comprising a magnetic bearing, the magnetic bearing comprising a plurality of magnets and a layer of diamagnetic material configured to repel the plurality of magnets. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 shows a comparison between a reflecting telescope utilizing a large mirror and an example embodiment of an OPA (optical phased array)-equipped telescope described herein.

[0012] [Diagram 2] FIG. 2 illustrates an example embodiment of aspects of an optical phased array element of an OPA-equipped telescope as described herein.

[0013] [Diagram 3] FIG. 2 illustrates an example embodiment of an optical phased array element of an OPA telescope as described herein.

[0014] [Figure 4] 1 illustrates the angular intensity profile of a beam emitted from an example telescope described herein.

[0015] [Figure 5A] FIG. 13 illustrates various simulated phase delays across the emitters of an example telescope described herein.

[0016] [Figure 5B] 5B shows the angular intensity profiles of beams emitted from an example ideal telescope as described herein and an example telescope having various phase delays across the emitter as shown in FIG. 5A.

[0017] [Figure 6A] FIG. 1 illustrates an example of an arrangement of optical phased array elements to form a compound telescope.

[0018] [Figure 6B] FIG. 1 illustrates an example of an arrangement of optical phased array elements to form a compound telescope.

[0019] [Figure 6C] FIG. 1 illustrates an example of an arrangement of optical phased array elements to form a compound telescope.

[0020] [Figure 7] 1 illustrates the angular intensity profile of a beam emitted from an example telescope described herein.

[0021] [Figure 8] 4A-4C show the angular intensity profile of a beam emitted from an example telescope described herein compared to another angular intensity profile.

[0022] [Figure 9] 1A-1C illustrate embodiments of an example diamagnetically levitated and magnetically controlled actuator.

[0023] [Figure 10] FIG. 1 illustrates an example telescope and diamagnetically levitated and magnetically controlled actuator.

[0024] [Figure 11] FIG. 1 illustrates an embodiment of a system.

[0025] [Figure 12] 1 illustrates an aspect of an example method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] In the following detailed description, reference is made to the accompanying drawings, which form a part of this specification. In the drawings, like numerals typically identify like elements unless otherwise indicated by the context. The example embodiments described in the detailed description, drawings, and claims are not intended to be limiting. Other embodiments may be used and other changes may be made without departing from the scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure as generally described and illustrated in the figures herein may be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are expressly contemplated herein.

[0027] I. Overview It is desirable in various applications to communicate at high bandwidth between far-flung systems moving relative to one another. For example, to provide communication between satellites in a satellite constellation configured to provide wireless data services (e.g., Internet access) to systems on Earth, large amounts of communication traffic may be transmitted through satellites in space to relatively few systems on the Earth's surface. Such high bandwidth communication is advantageously provided by line-of-sight optical communication links. However, these optical communication links typically require steering of optical beams transmitted to other systems to account for relative motion and rotation (e.g., of the orbiting satellites). Furthermore, at long distances (e.g., between orbiting satellites), the diffractive spread of such optical beams can become a significant factor, which leads to the use of steerable large aperture (e.g., several centimeters or more) telescopes or other optical systems to match the small aperture of on-board optical emitters / detectors to large aperture beams that can account for the diffractive beam spread at such distances. Steering of such large diameter beams may be accomplished by pointing the telescope or other optics used to generate the beam (e.g., a aiming mirror mounted on a galvanometer), steering all or part of such optics, and / or steering the body of the satellite or other platform as a whole.

[0028] As mentioned above, conventional telescopes that rely on separate reflective / refractive elements separated by large open space volumes (through which optical energy is received / transmitted by the telescope) exhibit large volumes, large masses, and large rotational inertia. As a result, more expensive, heavier, and more expensive steering mechanisms (e.g., higher rated servo motors) may be required, and / or the use of such conventional telescopes may be incompatible with volume, mass, cost, temperature, and / or power constrained applications (e.g., applications with small volume, mass, cost, and power and thermal budgets of cubesats or other small satellite systems). Described herein is an optical phased array (OPA) onboard system that can convert an optical beam from a small optical fiber input into a multi-centimeter diameter beam using a substantially flat structure. By replacing a conventional telescope with such a lightweight, substantially flat optical system, the 2D form factor of the OPA offers significant size, weight, and power reductions compared to conventional telescopes for the corresponding steering systems typically used to orient such optical systems (e.g., in accordance with the speed and accuracy requirements of a free-space optical communication terminal). Figure 1 compares a conventional telescope (left) with empty space for beam propagation and several mirrors, mounts, and a structure integrated with an example of an OPA embodiment described herein (right). Such an OPA-mounted system is more compact and lightweight, leading to direct savings in mass, rotational inertia, and volume, and may also indirectly reduce the weight, volume, power requirements, and cost of the associated steering mechanisms.

[0029] In other optical phased array beamforming systems, the phased array comprises multiple emitters (e.g., optical gratings) for emitting portions of a beam, and the phase of the light emitted from each emitter is controlled by a respective phase shifting element (e.g., a portion of a waveguide that can be heated to control the relative phase delay exhibited by the waveguide). The phase delay for each emitter is then controlled in a specific pattern to control the overall direction or other characteristics of a composite beam emitted from such a solid-state steerable phased array (a combination of light emitted from each of the emitters at their respective different controlled phase delays relative to a common optical input to the phased array). This leads to high speed non-mechanical beam steering capabilities.

[0030] However, conventional approaches to generate large aperture (e.g., apertures greater than one centimeter in diameter) optical beams from such phased arrays, while also achieving a wide field of view for beam steerability, use a large number of very small individual emitters. This results in very complex devices that include many (e.g., thousands or millions) of phase shifters, each of which is powered and controlled to generate the beam. Furthermore, the steerable beams emitted from such phased arrays can be inefficient due to emission of optical energy in significant side lobes (which can be related to the spacing between the individual emitters of such phased arrays). The efficiency of such phased arrays is further reduced by the power used to operate the array's phase shifters (e.g., heaters to control the temperature-dependent phase delay of its waveguides).

[0031] The embodiments described herein provide an improvement over conventional steerable phased arrays by using one or more "static" sub-OPAs (or "optical expanding elements") in which the relative phase matching between different optical emitters is not controlled. Each optical expanding element comprises multiple emitters (e.g., emitter gratings) fed from a single input waveguide through a set of mode expanders (e.g., tapers) and optical splitters such that the phase matching between the light output from (or input to) each emitter is not independently controllable and does not vary significantly over time between emitters relative to the phase matching of the corresponding light input to (or output from) the input waveguide. Thus, the beam direction, aperture, and other optical properties of the light emitted from (or received through) such optical expanding elements are not controllable and are set at the time of manufacture. Eliminating the steering function from the individual optical expanding elements also simplifies their design and manufacture. This allows OPAs as described herein to be used for near-term integration into size-, weight-, and power- (SWaP-) constrained platforms (such as cubesats, aircraft, or handheld devices). Alternatively, the steering function can be provided by mechanical actuators, as described above. The relative reduction in size, weight, and complexity of such non-steerable OPAs translates into size, weight, and cost savings over utilizing conventional telescopes that are steered to expand the beam aperture.

[0032] The improved OPA described herein may be comprised of a single such light-expanding element. Alternatively, an OPA may be formed from multiple such light-expanding elements mounted together (e.g., on a common substrate steered by an actuator) and fed by a single optical waveguide (e.g., coupled to an optical emitter and an optical detector to facilitate utilizing such a combined OPA for optical communication). The properties of the combined beam emitted from such an OPA may be controlled by controlling the phase matching of each of the light-expanding elements relative to one another. This may be done, for example, by attaching a fixed phase plate to each of the light-expanding elements during manufacture so that the individual portions of light emitted from each light-expanding element are appropriately phase matched for combining into a beam whose direction can be steered by mechanically rotating the OPA. Additionally or alternatively, a phase shifter or other path length control mechanism may be provided, one for each light-expanding element, to improve the properties of the combined beam emitted (e.g., to account for manufacturing variations in the light-expanding elements) and / or to provide a degree of non-mechanical (e.g., solid-state) beam steering. By significantly reducing the number of such phase shifters (from thousands or millions per OPA to tens of ones, one for each beam-expanding element of the OPA), such OPAs can be much more efficient than previous steerable phased arrays. Furthermore, the beam characteristics of the light emitted from each such beam-expanding element can be significantly improved (e.g., with respect to improved emitter spacing and size, or with respect to omission of a phase shifter corresponding to each emitter) with respect to previous steerable phased arrays, resulting in no or significantly reduced side lobe emissions. Thus, the composite beam emitted as a combination of the sub-beams emitted from an assembly of such beam-expanding elements can also be improved with respect to spurious side lobe emissions, resulting in increased efficiency.

[0033] For OPAs currently under development, eliminating or significantly reducing the steering function increases beam quality and beam generation efficiency while greatly simplifying design and manufacturing. Instead of thousands or millions of very fast phase control mechanisms required for steerable OPAs, the disclosed embodiments greatly reduce that number. For example, the number of phase shifters can be reduced to a few dozen phase control mechanisms (equal to the number of optical expansion elements used to form the OPA) to correct for manufacturing errors. Also, such phase shifters can operate with very little or perhaps no control feedback once set for the precise path length corrections used to generate beams of desired characteristics. Alternatively, as described above, the phase shifters can be controlled to slightly adjust the beam steering, for example, to allow slightly different transmit and receive beam directions through the same OPA without mechanically steering the OPA between transmit and receive. This can provide benefits in communicating with distant satellites (or other target communication systems) by allowing the OPA to transmit in a "forward" direction to compensate for the speed of light delay when transmitting to such a distant satellite.

[0034] In example embodiments of OPAs disclosed herein, the OPA can change the beam aperture of a transmitted signal (e.g., from a laser or other light source) from a few micrometers in diameter (e.g., a 5 micron diameter beam of 850 nm light emitted from a single mode fiber, or a 10 micron diameter beam of 1550 nm light emitted from a single mode fiber) to a few centimeters in diameter (e.g., 2.5 centimeters, 5 centimeters) (or do the reverse for received light) in a substantially flat, low-weight structure. This translates into a significant reduction in the size and weight of the beam expansion system, from a path of ∼10 cm in a conventional telescope for a 3 cm aperture, to less than 1 mm thick for an OPA. Furthermore, the way in which the OPA described herein shapes its output beam causes its “top-hat” beam shape to exhibit less divergence than the Gaussian beam shape of a conventional telescope. Additionally, the mechanical actuators used to steer the beam (by controlling the orientation of the OPA) can also be dramatically reduced in size, mass, and power, e.g., because they do not include or interface with large conventional telescope systems, and because the mass and / or rotational inertia of the OPA is much smaller than such conventional telescopes.

[0035] The light expanding elements described herein may form all or part of an OPA comprised of one or more such elements, and may be configured in various ways such that at least two emitters (e.g., emitter gratings) of the light expanding element receive respective corresponding portions of an input light beam to the light expanding element and emit respective corresponding portions of a composite output light beam of the OPA with the light expanding element. This may include the at least two emitters receiving respective corresponding portions of the input light beam through a beam splitter of the light expanding element. Thus, the relative phase between the light emitted from each of the at least two emitters of the light expanding element is static and uncontrollable (however, the relative phase between the input light beam and the emitters may be controllable by a single phase shifter of the light expanding element that operates to add an adjustable phase delay common to all of the emitters of the light expanding element). Such a beam splitter may be configured to split a single input light beam (e.g., received by a waveguide of an element that also includes a controllable phase shifter) across multiple emitters of the element. For example, the beam splitter may include a plurality of two-way beam splitters arranged as a binary tree to split the input light beam 256 times across the 256 emitters of the light expanding element.

[0036] Each emitter may be a long emitter grating configured to receive input light and emit the input light along the length of the grating in a pattern that forms a respective portion of the beam of light emitted from the element. FIG. 2 shows top and side views of such an emitter grating of a light expanding element. As shown, an input waveguide (e.g., a "single mode waveguide") from a beam splitter to the emitter is optically coupled to the emitter grating ("grating") through an optical mode expander (e.g., ("taper") shown in FIG. 2). The emitter comprises a plurality of gratings formed in the waveguide such that each emitter emits a respective portion of the light in the waveguide. The shape (width, thickness), optical properties (e.g., refractive index), and number of gratings, as well as the shape (width, thickness, length) and optical properties (e.g., refractive index) of the emitter's waveguide may be specified such that the light emitted from each grating constructively interferes to form the beam of light emitted from the emitter. Multiple such emitters (and associated mode expanders (e.g., tapers), waveguides, beam splitters, etc.) may be formed parallel to one another across a single light-expanding element to provide a light-expanding element that emits a composite light beam formed from corresponding portions of the light emitted from each of the element's emitters.

[0037] It should be noted that examples are often described throughout this disclosure showing an OPA or its optical expansion element receiving light from an input beam having a first aperture (e.g., from an input single-mode waveguide coupled to a laser or other optical emitter) and emitting the received input beam as an output composite beam having a wider second aperture. It is important to note that this direction of light propagation (input of a small aperture beam to the OPA, emission of a wide aperture beam from the OPA) is intended as a non-limiting illustration of the optical properties of such OPAs and related devices. Such OPAs and related devices can also operate in reverse to receive light from the environment via the OPA (e.g., from a wide aperture beam transmitted to the OPA from a remote system) and direct such received light to the "input" of the OPA (e.g., as a much smaller aperture beam that can be directed to a silicon avalanche photodiode or other light detecting element).

[0038] An example embodiment of the detailed elements of a light expanding element having multiple such emitter gratings (which may form all or part of the OPA described herein) is shown in FIG. 3. An optical signal is coupled into / out of the element from a light source / photodetector outside the element (e.g., from a directly modulated laser diode via an optical fiber). An external beam splitter tree (not shown) may distribute the signal to the inputs of each element of the multi-element OPA. The single light expanding element shown in the figure comprises a single phase shifter (e.g., a thermal phase shifter) following the beam splitter tree, and a set of mode expanders (e.g., tapers) to expand the beam width from the beam width in the beam splitter to the width of the emitter grating. A vertical grating coupler then outputs a two-dimensional beam that is substantially uniform in amplitude and phase. The element size may be expanded along the length of the emitter grating such that the phase of the emitted light is stable along the length of the emitter, so that the emitted beam remains substantially uniform. The feasible length of such an emitter may be increased by improving manufacturing tolerances. For example, the manufacturing tolerances used to create practical devices for experimental validation allowed the creation of emitter gratings having lengths of approximately 5 millimeters.

[0039] It should be noted that the integration of a phase shifter onto the light expanding element is intended as a non-limiting example embodiment, and that such a phase shifter could be formed separately from the light expanding element.

[0040] If the OPA is formed from multiple such light expanding elements, the thermal (or otherwise constructed) phase shifters may be controlled so that their outputs are coherently combined. This may involve adjusting the phase delay of each light expanding element to compensate for manufacturing length differences between the elements. For example, a 5 cm array may be produced with about 80 light expanding elements, each having dimensions of about 5 mm x 5 mm that can be manufactured cost-effectively while maintaining acceptable beam uniformity. Such a relatively small number of phase shifters (corresponding to the number of light expanding elements) is easily managed with a slow control loop to account for any temperature drift.

[0041] Figure 4 shows the angular dependence of beam intensity when emitted from such an optical emitter element. An example of an optical emitter element used to produce this result was constructed as shown in Figure 3 with 256 emitter gratings, each having a width of 18.5 microns and a length of 4.85 millimeters, spaced on 19.5 microns centers, and emitting light at 1550 nanometers. As shown, the main beam emitted from such an optical expansion element comprises more than 97.14% of the total optical output of the element.

[0042] The number of emitter gratings, their length, and their width can be selected to increase the overall efficiency and light output of each light expanding element. For example, fewer and wider emitters utilize less element area for the beam splitter, but longer mode expanders to match the mode of the waveguide from the beam splitter to the width of the emitter. Conversely, narrower emitters utilize shorter mode expanders, but more element area is applied to the beam splitter. In practice, light expanding elements with similar dimensions as described above can allocate more than 97% of the light expanding element area to emitter gratings (less than 3% of the light expanding element area is used for mode expanders and beam splitters). Other configurations can maintain a ratio of element area occupied by emitter gratings to element area occupied by mode expanders and beam splitters of more than 19:1.

[0043] In practice, the relative phase between the light received by the emitter gratings of the light expanding element varies across the elements. These phase differences from the ideal (i.e., constant uniform phase across all emitters) can lead to degradation of the quality of the beam emitted from the element. The extent of this degradation was simulated for a 256 emitter element with 18.5 micron wide emitters and a 5 mm fabrication coherence length. Figure 5A shows the simulated phase of each of the emitters relative to the input beam phase (0 degrees) simulated using a random walk. Figure 5B shows the angular dependence of the beam intensity emitted from such a light emitter element (showing phase variation across emitters as shown in Figure 5A). As can be seen, this imperfect beam profile ("with phase variation") deviates only slightly from the ideal beam profile ("ideal") emitted from a hypothetical light expanding element that does not show any phase variation between emitters.

[0044] The improved OPA described herein may be formed from a single such light expanding element or multiple such elements. An OPA may be formed from an array of multiple light expanding elements to provide a wider aperture beam formed from the combined output of the multiple elements. The multiple elements of such a composite OPA may be fed from the same input beam or waveguide (e.g., coupled to a light emitter and / or a light detector used to achieve long distance optical communication via the OPA) via one or more beam splitters. The phase of the common input (or output) light to each of the individual light expanding elements may be controlled by a respective phase shifter (e.g., a phase shifter formed on each of the expanding elements) to improve the quality of the composite beam emitted from the OPA (e.g., to account for manufacturing variations between elements, to account for non-uniform heating across the OPA), to achieve some degree of non-mechanical steering of the composite beam (e.g., to change between a "transmit direction" when a distant satellite receives the transmitted beam and a "receive direction" when the distant satellite transmits the beam), or to provide some other advantage. In such an example, a mechanical actuator that adjusts the mechanical orientation of the entire array may be operated to make coarse adjustments to the direction of the beam emanating therefrom over a wide range of angles, while operation of the phase shifters to adjust the relative phase of the light emitted from each of the beam expanding elements may be utilized to make fine adjustments to the direction of the beam over a relatively narrow range of angles (e.g., over a range of less than a degree). Additionally or alternatively, a fixed phase plate or other material may be disposed on the beam expanding elements to account for manufacturing variations or to otherwise adjust the characteristics of the composite beam emanating therefrom.

[0045] The light expanding elements of such a composite OPA may be arranged in various ways to provide a composite beam with a larger aperture. The light expanding elements of such an OPA may be mechanically attached to a substrate (e.g., a substrate coupled to a two-axis actuator configured to steer the OPA) using an adhesive or by some other means. The pattern and number of light expanding elements of such a composite array may be defined in various ways. For example, FIG. 6A shows an OPA formed from 19 light expanding elements and providing a composite beam with an aperture of 2.5 centimeters. In another example, FIG. 6B shows an OPA formed from 80 light expanding elements and providing a composite beam with an aperture of 5 centimeters. In yet another example, FIG. 6C shows an OPA formed from 82 light expanding elements and providing a composite beam with an aperture of 5 centimeters.

[0046] Because each element is associated with a respective resistively heated phase shifter (e.g., formed on each element), the total power consumption of the OPA is significantly reduced compared to a fully steerable phased array (i.e., an array in which each emitter grating or other optical emitter element is coupled to a respective phase shifter) because the total number of such phase shifters is significantly reduced from the thousands or millions used in phase shifter-per-emitter arrays. For example, if each phase shifter utilizes 10 mW of power, then the OPA of FIG. 6A utilizes only 190 mW, the OPA of FIG. 6B utilizes only 800 mW, and the OPA of FIG. 6C utilizes only 820 mW.

[0047] Such OPAs formed from multiple light expanding elements as described herein exhibit various benefits in terms of the quality of the beams emitted therefrom when compared to phased arrays with phase shifters per emitter (reduced side lobe missions compared to such phased arrays) and when compared to conventional telescopes. FIG. 7 shows the angular dependence of the beam intensity when emitted from the 82 light expanding element OPA shown in FIG. 6C. FIG. 8 shows the angular dependence of the beam intensity when emitted from the 82 light emitter element OPA shown in FIG. 6C ("5 cm phased array"), providing for comparison a theoretical diffraction-limited ideal beam profile emitted from a 5 cm aperture ("Airy Disk") and a beam profile emitted from a conventional telescope having a 5 cm aperture and emitting an optical 4.45 cm Gaussian beam profile through that aperture ("4.45 cm diameter Gaussian through 5 cm aperture"). As shown, the multi-element composite OPA significantly outperforms the conventional telescope and approaches theoretical diffraction-limited performance.

[0048] The reduction in size, weight, and rotational inertia of such OPAs also provides indirect benefits by relaxing the constraints (e.g., torque, speed, precision, etc.) on the actuators used to steer such OPAs compared to steering of conventional telescopes to achieve the same speed and precision of steering, which translates into reduced size, weight, cost, complexity, and power requirements for such steering.

[0049] A steering actuator used to steer the OPA described herein can be configured in a variety of ways. In some examples, the actuator can include two or more servos, motors, or other actuators mechanically coupled to the OPA to steer the OPA. In some examples, the actuator can include a magnetic bearing and multiple coils. The magnetic bearing can include multiple magnets and a layer of diamagnetic material configured to repel the multiple magnets to form a low-friction (or frictionless) magnetic bearing between the rotor of the actuator (to which the OPA is coupled) and the stator of the actuator (to which the actuator and the OPA are coupled to the remainder of the satellite or other system of which it is a part). A coil located in a portion of the actuator facing the magnet (e.g., a stator coil, with a permanent magnet located in the rotor and a diamagnetic material located in the stator) can then be driven by a current to exert a force on the magnet to adjust the orientation of an optical phased array attached to the actuator.

[0050] FIG. 9 shows, by way of example, an embodiment of such a diamagnetically levitated actuator. The actuator comprises a plurality of permanent magnets ("magnet array") arranged along a hemispherical surface and disposed within a hemispherical recess in a diamagnetic material ("diamagnetic material", e.g., pyrolytic carbon) such that the rotor of the actuator (with the permanent magnets) is magnetically repelled from the diamagnetic material, thereby providing a magnetic bearing therebetween. In the example shown in FIG. 9, the actuator is coupled to a single mirror, and the actuator can be operated to control the orientation of the mirror. This can be done, for example, to control the deflection direction of a beam of light, as shown in the right portion of FIG. 9. Such an actuator may instead be coupled to an OPA as described herein to allow the actuator to be operated to control the orientation of the OPA, and thus the orientation of the light beam emitted therefrom / received by it.

[0051] FIG. 10 illustrates an example communication system with an OPA ("optical phased array," formed from multiple optical magnifying elements) described herein coupled to a diamagnetically levitated actuator. In particular, the OPA is attached to a hemispherical rotor of the actuator, which comprises multiple permanent magnets. The hemispherical rotor is disposed within a hemispherical recess in a stator of the actuator, which is formed from a diamagnetic material, thereby providing approximately 500 microns of magnetically supported separation between the rotor and stator. Multiple coils are disposed within the stator (e.g., within or behind the diamagnetic material, not shown) through which current can be passed to control the orientation of the OPA by exerting a magnetic force on the permanent magnets in the rotor.

[0052] In the embodiment of the actuator shown in Figure 10, the total weight of the actuator (including the carbon fiber diamagnetic head, magnet, encoder, peripheral electronics, fixture, circuit board, drive coil, coil driver, and microcontroller) is only 97 grams. The actuator and associated controller were configured to operate in a "fast" mode to initiate a link (e.g., for rapid orientation from one target to another) and in a "slow" mode to maintain the link at a lower power consumption. The system can operate at less than 231 mW in the fast mode and less than 82 mW in the slow mode.

[0053] The actuator of FIG. 10 also shows several magnetic clamps ("magnetic clamps") that can be actuated to mechanically secure the rotor. This can be done, for example, to prevent damage or misalignment of the rotor (e.g., from exiting the hemispherical recess of the stator) during transport (e.g., during launch of a satellite including the OPA and actuator) or during any other period when it is advantageous to mechanically secure the rotor and OPA (e.g., when the OPA is not being used to conserve power in the coils used to orient the rotor and / or maintain the rotor within the hemispherical recess of the stator). Such magnetic clamps may be operable multiple times (e.g., by being drivable between "locked" and "unlocked" states by a motor or other actuator), or may be operable once to save weight, cost, or other factors (e.g., to secure the rotor only before being actuated to release the rotor by applying heat or a magnetic field to decouple the clamp from the rotor and / or to weaken or remove the magnetic field of the clamp).

[0054] The OPA is electrically and optically coupled to the rest of the communication system (e.g., to a laser or other light emitter, to a light detector, to control electronics for operating a phase shifter in the light magnifying element of the OPA) via electrical cables ("control electronics connectors") and optical fibers ("fiber optic connections"), although this is intended as a non-limiting example embodiment only. For example, the optical fibers can be omitted by placing the light emitters and / or light detectors within the rotor (e.g., using electrical cables to power and control those elements). In another example, the electrical cables can be omitted if the OPA lacks electronic phase shifters or other electronic elements. The electrical cables may be used to control the phase shifters of the OPA and / or provide other functions (e.g., to operate optical emitters and / or detectors optically coupled to the OPA, to drive coils of the actuator in examples where the coils are located on the rotor and permanent magnets are located on the stator of the actuator, to operate magnetic field sensors and / or encoders used to determine the orientation of the OPA and / or the field generated by the coils, or to provide some other function).

[0055] Further description of the disclosed approaches is contained in the Appendix, which is part of this application and is incorporated by reference in its entirety as if fully set forth herein. The Appendix includes a presentation entitled "Passive Optical Phased Arrays." Additionally, the references set forth herein and in the appendices are also part of this application and are incorporated by reference in their entirety as if fully set forth herein.

[0056] II. System Example 11 illustrates an example system 1100 that may be utilized to implement the methods described herein and / or that may be or include part or all of one or more systems described herein. By way of example, and without limitation, system 1100 may be all or part of a satellite or part of a satellite (e.g., a communications subsystem of a satellite), a CubeSat or part of a CubeSat or other microsatellite system, an autonomous vehicle or part of an autonomous vehicle, or some other system to provide high-aperture and high-performance line-of-sight optical communications between two or more systems whose relative positions and / or orientations may change over time. It should be understood that system 1100 may represent a physical device, such as a satellite, a particular physical hardware subsystem that may be part of a larger system (e.g., by being mechanically, electrically, thermally, and / or otherwise coupled to a host system), or other combination of hardware and software configured to perform functions and / or incorporate elements described herein.

[0057] As shown in FIG. 11, the system 1100 may include a communications interface 1102, a processor 1103, an optical phased array (OPA) 1108, an actuator 1104 configured to mechanically adjust an orientation of the OPA 1108, an optical emitter 1105 coupled to the OPA 1108 and configured to emit a beam of light from the OPA 1108 (e.g., toward a satellite far away in space) by providing light to the OPA 1108, an optical detector 1106 coupled to the OPA 1108 and configured to receive a beam of light from an environment of the OPA 1108 (e.g., from a satellite far away in space) by receiving light from the OPA 1108, one or more phase shifters 1107 that may be formed as part of the OPA 1108 or may be separate therefrom, and data storage 1109, all of which elements may be communicatively linked to each other by a system bus, network, or other connection mechanism 1110. An optical phased array, such as the static OPAs described herein, may comprise one or more sets of two or more emitter gratings or other static optical emitter elements that are fed from a common optical feed and have a static, uncontrolled relative phase relationship between each other with respect to the phase of light received via the common optical feed.

[0058] The communications interface 1102 may function to enable the system 1100 to communicate with other devices, access networks, and / or transport networks via means other than the OPA 1108 using analog or digital modulation of electrical, magnetic, electromagnetic, optical, or other signals. Thus, the communications interface 1102 may facilitate circuit-switched and / or packet-switched communications, such as Internet Protocol (IP) or other packetized communications. For example, the communications interface 1102 may comprise a chipset and antenna arranged to wirelessly communicate with a wireless access network or access point. The communication interface 1102 may also take the form of or include a wired interface (such as an Ethernet, Universal Serial Bus (USB), or High-Definition Multimedia Interface (HDMI) port) for communicating with other systems (e.g., a master controller or system bus of a satellite in which the system 1100 forms a long-range optical communication subsystem). The communication interface 1102 may also take the form of or include a wireless interface (such as Wifi, BLUETOOTH, Global Positioning System (GPS), or a wide-area wireless interface (e.g., WiMAX or 3GPP Long Term Evolution (LTE))). However, other forms of physical layer interfaces and other types of standard or proprietary communication protocols may be used in the communication interface 1102. The communication interface 1102 may also include multiple physical communication interfaces (e.g., a Wifi interface, a BLUETOOTH interface, and a wide-area wireless interface).

[0059] In some embodiments, the communication interface 1102 may function to enable the system 1100 to communicate with other devices, remote servers, access networks, and / or transport networks. In some examples, aspects of the communication interface 1102 (e.g., an encoder, a decoder, a multiplexer, a timer or oscillator, a protocol management controller, or a state machine) may be used in cooperation with the actuator 1104, the optical emitter 1105, the optical detector 1106, and / or the phase shifter 1107 to perform long-range optical communications with one or more remote systems (e.g., one or more other satellites) via the OPA 1108. Additionally or alternatively, all or a portion of such functionality may be implemented by the processor 1103.

[0060] The processor 1103 may include one or more general purpose processors (e.g., microprocessors) and / or one or more special purpose processors (e.g., digital signal processors (DSPs), graphics processing units (GPUs), floating point units (FPUs), network processors, tensor processing units (TPUs), or application specific integrated circuits (ASICs)). The data storage 1109 may include one or more volatile and / or non-volatile storage components (e.g., magnetic, optical, flash, or organic storage) and may be fully or partially integrated with the processor 1103. The data storage 1109 may comprise removable and / or non-removable components.

[0061] The processor 1103 may be capable of executing program instructions 1118 (e.g., compiled or uncompiled program logic and / or machine code) stored in the data storage 1109 to perform various functions described herein. Thus, the data storage 1109 may include a non-transitory computer-readable medium having stored thereon program instructions that, when executed by the system 1100, cause the system 1100 to perform any of the methods, processes, or functions disclosed in this specification and / or the accompanying drawings. Execution of the program instructions 1118 by the processor 1103 may result in the processor 1103 utilizing the data 1112.

[0062] By way of example, the program instructions 1118 may include an operating system 1122 (e.g., an operating system kernel, device drivers, and / or other modules) installed on the system 1100, as well as one or more application programs 1120 (e.g., functionality for performing data collection, data routing and / or forwarding, communication with an Earth station, or other mission objective activities, functionality for determining a position and / or orientation of the system 1100 in space, determining a relative position and / or orientation of another satellite system in space, and operating to optically communicate with another satellite system via the OPA 1108). The data 1112 may include calibration data (e.g., information regarding the phase dependence of orientations or other characteristics of sub-beams emitted from individual static OPA subelements of a composite OPA 1108 formed from multiple static OPA subelements) 1114, and / or temporal data 1116 regarding the time-dependent position and orientation of the system 1100 and / or other systems (e.g., other satellites) with which the system 1100 may communicate.

[0063] The application programs 1120 may communicate with the operating system 1122 through one or more application programming interfaces (APIs). These APIs may facilitate, for example, the application programs 1120 to send or receive information via the communications interface 1102, receive and / or send data via the OPA 1108, etc.

[0064] The actuator 1104 may comprise, for example, a servo, a motor, multiple magnetic coils and corresponding permanent magnets on a rotor (e.g., a rotor that provides low or frictionless magnetic bearings by diamagnetically levitating from a stator that includes the coils) to direct a beam of light emitted from / detected via the OPA 1108 to another system (e.g., a satellite) with which the system 1100 may optically communicate, or some other means for adjusting the orientation of the OPA 1108 relative to the system 1100.

[0065] The optical emitter 1105 may include one or more lasers, light emitting diodes, or other light emitting elements whose time-varying patterns of intensity may be controlled for optical communication with one or more remote systems via the OPA 1108. The wavelength and / or aperture of the optical emitter 1105 may be specified relative to the OPA 1108 to match the optical emitter 1105 to the OPA 1108 (e.g., to match the mode, aperture, wavelength, or other characteristics of the input waveguide, phase shifter, beam splitter, mode expander, and / or emitter grating of the OPA 1108). For example, the optical emitter 1105 may comprise a 1550 nanometer fiber optical amplifier or an 850 nanometer semiconductor optical amplifier.

[0066] The photodetector 1106 may comprise one or more avalanche photodetectors, photodiodes, avalanche photodiodes, single photon detectors, or other photodetecting elements that may be operated to detect a time-varying pattern of light intensity received from one or more remote systems via the OPA 1108 to facilitate optical communication. The wavelength and / or shape of the photodetector 1106 may be specified relative to the OPA 1108 to match the photodetector 1106 to the OPA 1108 (e.g., to match the mode, aperture, wavelength, or other characteristics of the input waveguide, phase shifter, beam splitter, mode expander, and / or emitter grating of the OPA 1108). For example, the photodetector 1106 may comprise one or more silicon avalanche photodiodes.

[0067] The phase shifter 1107 may include various elements configured to adjust the phase of light emitted from / received by a subelement of the OPA 1108 (e.g., emitted from / received by an individual optical emitter element having multiple emitter gratings and a single optical input / output having a static optical phase relationship with each of the emitter gratings) relative to the phase of light received by / emitted from an optical input / output port of the subelement. For example, the phase shifter 1107 may include a thermal phase shifter configured to adjust the amount of phase delay imparted by a waveguide to light passing through the waveguide by electrically applying a controlled amount of heating to the waveguide. The phase shifter 1107 may be integrated into the sub-element of the OPA 1108 (e.g., a single phase shifter formed as a waveguide and associated heater elements and electrical conductors in silicon or other material in which the emitter grating, mode expander, beam splitter, or other components of the sub-element are also formed) or may be separate from the sub-element (e.g., separate optical phase shifters coupled to the sub-element in one direction and coupled to the optical emitter 1105 and / or optical detector 1106 via a beam splitter in the opposite direction). In some examples, multiple phase shifters corresponding to different waveguides may be associated with each sub-element of the OPA 1108. This may be done in combination with a wavelength-selective filter or other element, for example, to allow the direction of the beam of light from the OPA 1108 at a first wavelength (e.g., a transmit wavelength) to be slightly changed from the direction of the beam of light from the OPA 1108 at a second wavelength (e.g., a receive wavelength). This allows full-duplex communication with satellites that are far enough away from system 1100 that the time-of-flight delay between system 110 and the satellite means that the received optical transmission is received from a different direction than the transmitted optical transmission was sent (e.g., to account for relative motion and speed-of-light delay, the optical transmission "leads" the current relative position of the target, and the received optical signal is received from the past relative position of the target).

[0068] The optical phased array 1108, optical emitter 1105, optical detector 1106, phase shifter 1107, and / or elements thereof (e.g., waveguides, mode expanders, tapers, beam splitters, emitters (e.g., grating emitters)) may be adapted to provide communication or other optical beam transmission / reception functions described herein for one or more wavelengths. For example, these elements of the system 1100 may be adapted to facilitate communication at one or more wavelengths between 380-2400 nm. In some examples, these elements of the system 1100 may be adapted to facilitate communication at one or more wavelengths between 600-800 nm to provide more energy-efficient communication by utilizing more efficient optical emitters available in that range.

[0069] III. Method example 12 is a flow chart illustrating an example method 1200. The method 1200 comprises operating 1210 an actuator to direct the optical phased array towards a target. The method 1200 further comprises operating 1220 a plurality of phase shifters of the optical phased array to control a direction of an output optical beam of the optical phased array in a first direction relative to the optical phased array during a first time period. The method 1200 further comprises optically transmitting first information to the target during the first time period, where optically transmitting the first information to the target during the first time period comprises (i) operating an optical emitter to generate a beam of light that encodes the first information, and (ii) receiving 1230 the beam of light generated by the optical emitter as an input optical beam by the optical phased array while the optical phased array is directed towards the target. Method 1200 further includes operating (1240) the plurality of phase shifters to control a direction of the output optical beam in a second direction relative to the optical phased array during a second time period, where the second direction is different from the first direction. Method 1200 further includes optically receiving (1250) second information from the target during a second time period, where optically receiving the second information from the target during the second time period includes operating an optical detector optically coupled to the optical phased array to detect the second information optically transmitted from the target and received via the optical phased array. Method 1200 may include additional or alternative features.

[0070] IV. Enumerated Example Embodiments Accordingly, embodiments of the present disclosure may relate to one of the enumerated example embodiments (EEE) set forth below, it being understood that features shown with respect to one EEE may be combined with other EEE.

[0071] EEE1 is a system comprising: (i) an optical phased array, the optical phased array comprising a first optical expansion element having at least two emitter gratings and a beam splitter, the at least two emitter gratings configured to receive respective portions of an input optical beam via the beam splitter and to emit respective corresponding portions of a composite output optical beam of the optical phased array, the input optical beam having a first aperture smaller than a second aperture of the composite output optical beam, and a relative phase between light emitted from each of the at least two emitter gratings is static; and (ii) a steering actuator mechanically coupled to the optical phased array and configured to adjust an orientation of the optical phased array.

[0072] EEE2 is a system of EEE1, wherein the steering actuator comprises a magnetic bearing, the magnetic bearing comprising a plurality of magnets and a layer of diamagnetic material configured to repel the plurality of magnets.

[0073] EEE3 is any of the systems of EEE1-2, wherein the optical phased array comprises a plurality of optical expansion elements including a first optical expansion element, each optical expansion element of the plurality of optical expansion elements receiving a respective portion of the input optical beam and emitting a respective portion of the composite output optical beam.

[0074] EEE4 is the system of EEE3, further comprising a fixed phase plate, the fixed phase plate providing a respective static phase adjustment to light emitted from each of the light expanding elements of the plurality of light expanding elements.

[0075] EEE5 is any of the systems of EEE3-4, further comprising a plurality of phase shifters, each phase shifter of the plurality of phase shifters operable to adjust a phase of light emitted from a respective one of the plurality of beam expanding elements relative to a phase of the input beam, and a controller, the controller configured to perform controller operations including operating the plurality of phase shifters to control a direction of the composite output beam relative to the optical phased array.

[0076] EEE6 is the system of EEE5, further comprising an optical emitter configured to generate an input optical beam received by the optical phased array, and an optical detector optically coupled to the optical phased array to receive light received by the optical phased array from a direction of the composite output optical beam via the multiple optical magnifying elements. The controller operations further include operating the steering actuator to steer the optical phased array towards a target, operating the multiple phase shifters during a first time period to control a direction of the composite output optical beam in a first direction relative to the optical phased array, operating the optical emitter during the first time period to generate a beam of light encoding first information, thereby optically transmitting the first information to the target, and operating the multiple phase shifters during a second time period to control a direction of the composite output optical beam in a second direction relative to the optical phased array, the second direction being different from the first direction, and operating the optical detector during the second time period to detect second information optically transmitted from the target and received via the optical phased array.

[0077] EEE7 is any one of the systems EEE1 to EEE6, further comprising an optical emitter, the optical emitter being coupled to the optical phased array via a flexible optical fiber.

[0078] EEE8 is any of the systems EEE1-7, wherein the input light beam includes light having a wavelength between 380 nanometers and 2400 nanometers.

[0079] EEE9 is any of the systems of EEE1-8, wherein the first optical expansion element comprises a first region and a second region, each of the at least two emitter gratings is associated with a respective tapered optical waveguide, with each emitter grating receiving a respective portion of the input optical beam from the beam splitter, the at least two emitter gratings are disposed in the first region, and the tapered optical waveguide and the beam splitter are disposed in the second region, and a ratio between an area of ​​the first region and an area of ​​the second region is greater than 19:1.

[0080] EEE10 is any of the systems EEE1-9, wherein the second aperture of the combined output light beam is greater than 5 centimeters.

[0081] EEE11 is any of the systems of EEE1-10, and the system according to claim 1, wherein the system is a satellite system, and the system further comprises an optical emitter configured to generate an input optical beam received by the optical phased array, and a controller. The controller is configured to perform controller operations, the controller operations including operating a steering actuator to steer the optical phased array towards a target and operating the optical emitter to generate a beam of light encoding first information, thereby optically transmitting the first information to the target.

[0082] EEE12 is any of the systems EEE1-11, further comprising a photodetector, the photodetector optically coupled to the optical phased array to receive light received by the optical phased array from the direction of the output light beam via the multiple optical magnifying elements, the photodetector being an avalanche photodiode.

[0083] EEE13 is a method comprising: (i) operating a steering actuator to steer an optical phased array towards a target, the steering actuator being mechanically coupled to the optical phased array and configured to adjust an orientation of the optical phased array; (ii) operating a plurality of phase shifters of the optical phased array to control a direction of an output optical beam of the optical phased array in a first direction relative to the optical phased array, during a first time period; and (iii) optically transmitting first information to the target during the first time period, the optically transmitting first information to the target during the first time period comprising: (a) operating an optical emitter to generate a beam of light encoding the first information; (b) transmitting a first information to the target; (iv) operating the plurality of phase shifters to control a direction of the output optical beam in a second direction relative to the optical phased array during a second time period, the second direction being different from the first direction; and (v) optically receiving second information from the target during the second time period, the optically receiving second information from the target during the second time period comprising operating an optical detector optically coupled to the optical phased array to detect the second information optically transmitted from the target and received via the optical phased array.

[0084] EEE14 is the method of EEE13, wherein the steering actuator comprises a magnetic bearing and a plurality of coils, the magnetic bearing comprising a plurality of magnets and a layer of diamagnetic material configured to repel the plurality of magnets, and operating the steering actuator to steer the optical phased array towards the target includes adjusting an orientation of the optical phased array by controlling current supplied to the plurality of coils to exert a force on the plurality of magnets.

[0085] EEE15 is any one of the methods EEE13-14, wherein the photodetector is an avalanche photodiode.

[0086] EEE16 is any of the methods EEE13-15, wherein the output light beam has an aperture greater than 5 centimeters.

[0087] EEE17 is any of the methods of EEE13 to 16, wherein the optical phased array comprises a first optical expansion element having at least two emitter gratings and a beam splitter, the at least two emitter gratings are configured to receive respective portions of an input optical beam via the beam splitter and emit respective corresponding portions of a composite output optical beam of the optical phased array, the input optical beam has a first aperture that is smaller than a second aperture of the composite output optical beam, and a relative phase between the light emitted from each of the at least two emitter gratings is static.

[0088] EEE18 is the method of any of EEE13 to 17, wherein the beam of light encoding the first information comprises light having a wavelength between 380 nanometers and 2400 nanometers.

[0089] EEE19 is a product including a computer-readable medium having stored thereon program instructions which, when executed by a computing device, cause the computing device to perform operations to affect any of the methods of EEE13-18.

[0090] EEE20 is a system comprising: (i) an optical phased array configured to receive an input optical beam and emit an output optical beam, the input optical beam having a first aperture smaller than a second aperture of the output optical beam; and (ii) a steering actuator coupled to the optical phased array and configured to adjust an orientation of the optical phased array, the steering actuator comprising a magnetic bearing, the magnetic bearing comprising a plurality of magnets and a layer of diamagnetic material configured to repel the plurality of magnets.

[0091] V. Conclusion The particular arrangements shown in the figures should not be considered limiting. It should be understood that alternative embodiments may include more or less of each element shown in a given figure. Additionally, some of the illustrated elements may be combined or omitted. Still further, an example embodiment may include elements that are not shown.

[0092] Moreover, while various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are intended to be illustrative and not limiting, with a true scope and spirit being indicated by the following claims. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It is readily understood that the aspects of the present disclosure as generally described and illustrated in the figures herein may be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are contemplated herein.

Claims

1. 1. A system comprising: an optical phased array comprising a first beam expanding element having at least two emitter gratings and a beam splitter; the at least two emitter gratings configured to receive respective portions of an input light beam via the beam splitter and to emit respective portions of a composite output light beam of the optical phased array, the input light beam having a first aperture smaller than a second aperture of the composite output light beam, and a relative phase between light emitted from each of the at least two emitter gratings is static; a steering actuator mechanically coupled to the optical phased array and configured to adjust an orientation of the optical phased array; and A system comprising:

2. 10. The system of claim 1, wherein the steering actuator comprises a magnetic bearing, the magnetic bearing comprising a plurality of magnets and a layer of diamagnetic material configured to repel the plurality of magnets.

3. 2. The system of claim 1, wherein the optical phased array comprises a plurality of beam expanding elements including the first beam expanding element, each beam expanding element of the plurality of beam expanding elements receiving a respective portion of the input beam and emitting a respective portion of the composite output beam.

4. 4. The system of claim 3, further comprising a fixed phase plate, the fixed phase plate providing a respective static phase adjustment to light emitted from each of the beam expanding elements of the plurality of beam expanding elements.

5. The system of claim 3, further comprising: a plurality of phase shifters, each phase shifter of the plurality of phase shifters operable to adjust a phase of light emitted from a respective one of the plurality of light expanding elements relative to a phase of the input light beam; a controller configured to perform controller operations, the controller operations including: activating the plurality of phase shifters to control a direction of the composite output light beam relative to the optical phased array.

6. The system of claim 5, further comprising: an optical emitter configured to generate the input optical beam received by the optical phased array; a photodetector optically coupled to the optical phased array to receive light received by the optical phased array from the direction of the composite output light beam via the plurality of optical magnifying elements; Equipped with The controller operation further comprises: activating the steering actuator to steer the optical phased array towards a target; operating the plurality of phase shifters to control the direction of the composite output light beam in a first direction relative to the optical phased array during a first time period; operating the light emitter to generate a beam of light encoding first information during the first period, thereby optically transmitting the first information to the target; activating the plurality of phase shifters to control the direction of the composite output light beam in a second direction relative to the optical phased array during a second time period, the second direction being different from the first direction; operating the optical detector to detect second information optically transmitted from the target and received via the optical phased array during the second time period.

7. 13. The system of claim 1, further comprising an optical emitter, the optical emitter coupled to the optical phased array via a flexible optical fiber.

8. 10. The system of claim 1, wherein the input light beam comprises light having a wavelength between 380 nanometers and 2400 nanometers.

9. 2. The system of claim 1 , wherein the first light expanding element comprises a first region and a second region, each of the at least two emitter gratings is associated with a respective tapered optical waveguide through which each emitter grating receives a respective portion of the input light beam from the beam splitter, the at least two emitter gratings are disposed within the first region, the tapered optical waveguide and the beam splitter are disposed within the second region, and a ratio between an area of ​​the first region and an area of ​​the second region is greater than 19:

1.

10. 10. The system of claim 1, wherein the second aperture of the composite output light beam is greater than 5 centimeters.

11. 10. The system of claim 1, wherein the system is a satellite system, the system further comprising: an optical emitter configured to generate the input optical beam received by the optical phased array; a controller configured to perform controller operations, the controller operations including: activating the steering actuator to steer the optical phased array towards a target; activating the light emitter to generate a beam of light encoding first information, thereby optically transmitting the first information to the target.

12. 2. The system of claim 1, further comprising: A photodetector is provided, the optical detector is optically coupled to the optical phased array to receive light received by the optical phased array from a direction of the output light beam through the multiple optical magnifying elements, the optical detector being an avalanche photodiode.

13. 1. A method comprising: operating a steering actuator to direct the optical phased array towards a target, the steering actuator being mechanically coupled to the optical phased array and configured to adjust an orientation of the optical phased array; operating a plurality of phase shifters of the optical phased array to control a direction of an output light beam of the optical phased array in a first direction relative to the optical phased array during a first time period; optically transmitting first information to the target during the first time period; and optically transmitting the first information to the target during the first time period. activating a light emitter to generate a beam of light encoding the first information; receiving, by the optical phased array as an input light beam, the beam of light generated by the optical emitter while the optical phased array is directed towards the target; Operate the plurality of phase shifters to control the direction of the output light beam in a second direction relative to the optical phased array during a second time period, the second direction being different from the first direction; optically receiving second information from the target during the second time period, wherein optically receiving the second information from the target during the second time period comprises:

20. The method of claim 19, further comprising: operating an optical detector optically coupled to the optical phased array to detect the second information optically transmitted from the target and received via the optical phased array.

14. 14. The method of claim 13 , wherein the steering actuator comprises a magnetic bearing and a plurality of coils, the magnetic bearing comprising a plurality of magnets and a layer of diamagnetic material configured to repel the plurality of magnets, and wherein operating the steering actuator to direct the optical phased array towards the target comprises adjusting an orientation of the optical phased array by controlling current supplied to the plurality of coils to exert a force on the plurality of magnets.

15. 14. The method of claim 13, wherein the photodetector is an avalanche photodiode.

16. 14. The method of claim 13, wherein the output light beam has an aperture greater than 5 centimeters.

17. 14. The method of claim 13, wherein the optical phased array comprises a first optical expansion element having at least two emitter gratings and a beam splitter, the at least two emitter gratings configured to receive respective portions of an input optical beam via the beam splitter and to emit respective corresponding portions of a composite output optical beam of the optical phased array, the input optical beam having a first aperture smaller than a second aperture of the composite output optical beam, and a relative phase between light emitted from each of the at least two emitter gratings is static.

18. 14. The method of claim 13, wherein the beam of light encoding the first information comprises light having a wavelength between 380 nanometers and 2400 nanometers.

19. 20. An article of manufacture including a computer readable medium having stored thereon program instructions which, when executed by a computing device, cause the computing device to perform operations to affect a method according to any one of claims 13 to 18.

20. 1. A system comprising: an optical phased array configured to receive an input light beam and to emit an output light beam, the input light beam having a first aperture smaller than a second aperture of the output light beam; a steering actuator coupled to the optical phased array and configured to adjust an orientation of the optical phased array, the steering actuator comprising a magnetic bearing, the magnetic bearing comprising a plurality of magnets and a layer of diamagnetic material configured to repel the plurality of magnets.

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