NEAR-OMNIDIRECTIONAL OPTICAL RECEIVER, COMMUNICATION SYSTEM AND PLATFORM

The present invention includes embodiments of optical receivers, communication systems and communication platforms for receiving electromagnetic radiation (EMR) signals from a plurality of sources and/or directions. An embodiment of an optical receiver, a communication system, or a communication platform may include a Lüneburg lens. The Lüneburg lens allows incoming EMR to be directed to a photodetector. A processor in communication with the photodetector may be configured for calculating power gradient of energy density of the inbound optical signals, isolating discrete inbound optical signals, determining direction of the inbound optical light signals and gathering information transmitted in the inbound optical light signals.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates generally to optical communications systems. More particularly, the present invention relates to near-omnidirectional optical communications systems.

Description of Related Art

Optical communication methods between non-static point-to-point locations typically use a series of mirrors, stabilizers, and control systems to effectively allow the devices to be aimed at one another to complete the communication link. The primary challenges associated with this method of communication require high fidelity control systems and an inherent inability to receive multiple signals because otherwise the original intended communication link would have to be broken.

In view of the foregoing and for other reasons that will become clearer, there exists a need in the art for improved near-omnidirectional optical communication systems.

SUMMARY OF THE INVENTION

An embodiment of an optical communication receiver is disclosed. The embodiment of an optical communication receiver may include a photodetector having a sensor plane, the photodetector configured to receive incident optical light signals and detect optical signal energy density corresponding to x-y locations along the sensor plane. The embodiment of an optical communication receiver may further include a Lüneburg lens adjacent to the photodetector and configured to direct incident optical light signals onto the sensor plane of the photodetector. The embodiment of an optical communication receiver may further include a processor in communication with the photodetector configured for calculating power gradient of the optical signal energy density, isolating discrete signals, determining direction of the incident optical light signals and gathering information transmitted in the incident optical light signals.

An embodiment of an optical communication system is disclosed. The embodiment of an optical communication system may include an optical receiver configured to receive inbound optical signals, the optical receiver comprising a Lüneburg lens. The embodiment of an optical communication system may further include a processor in communication with the optical receiver and configured for calculating power gradient of energy density of the inbound optical signals, isolating discrete inbound optical signals, determining direction of the inbound optical light signals and gathering information transmitted in the inbound optical light signals.

An embodiment of a communication platform is disclosed. The embodiment of a communication platform may include at least one optical communication system, including an optical receiver configured to receive inbound optical signals, the optical receiver comprising a Lüneburg lens and a processor in communication with the optical receiver and configured for calculating power gradient of energy density of the inbound optical signals, isolating discrete inbound optical signals, determining direction of the inbound optical light signals and gathering information transmitted in the inbound optical light signals.

DETAILED DESCRIPTION

The disclosed methods and systems below may be described generally, as well as in terms of specific examples and/or specific embodiments. For instances where references are made to detailed examples and/or embodiments, it should be appreciated that any of the underlying principles described are not to be limited to a single embodiment but may be expanded for use with any of the other methods and systems described herein as will be understood by one of ordinary skill in the art unless specifically otherwise stated. It will be further understood that the embodiments of the invention described herein are not intended to be exhaustive or to limit the invention to precise forms disclosed. Rather, the embodiments selected for description have been chosen to enable one skilled in the art to practice the invention.

FIG.1shows a cross-sectional view an exemplary communication system, shown generally at arrow1, with a transmission section5surrounding an antenna section3. Exemplary transmission sections5can be made with a variety of transmission elements operating in tandem (e.g., a plurality of lens or mirror elements arranged in a plurality of rows or rings) or a continuous refraction medium shaped to refract EMR in a toward a predetermined area or point within the transmission section5(e.g., a Lüneburg lens). Transmission section5may completely surround the antenna section so that it can refract a plurality of optical paths7,9and11such that regardless of the incoming direction of each optical path, the optical path7,9, and11always ends at antenna section3. The thickness of transmission section5can be scaled based on the size of antenna section3. The size of antenna section3may be dependent on the properties of the chosen antenna section3(e.g., particular antenna elements may have a minimum size), so the thickness of transmission section5can be increased or decreased to reach a predetermined lens to antenna ratio. A wide variety of ratios can be used if the transmission section is thick enough to refract all incoming EMR to reach antenna section3. In exemplary embodiments, the transmission section5can be made with a gradient refractive index such that the index decreases radially from the center-most portion to the outer-most portion of the transmission section5. In these embodiments, the gradient refractive index facilitates bending incoming EMR towards the antenna section3and prevents backscattering of EMR at the outer surface of the transmission section5.

FIG.2illustrates a cross-sectional view of an exemplary communication system1with a spherical transmission section5surrounding an antenna section3. Input/output (I/O) lines21allow antenna section3to transmit information and data to other systems (not shown). In exemplary embodiments, transmission section5can be manufactured around antenna section3such that antenna section3is embedded within transmission section5. In other exemplary embodiments, antenna section3can be embedded within transmission section5after the transmission section is partially constructed, then transmission section5can be completed. In other exemplary embodiments, antenna section3can be embedded within transmission section5after the transmission section is fully constructed.

FIG.3A to3Cillustrate cross-sectional views of alternative embodiments of exemplary antenna sections3. In exemplary embodiments, antenna section3can be made with a plurality of antenna elements31. By using multiple antenna elements31, a user can determine the direction of incoming EMR based on which antenna elements received EMR. Antenna elements31can each be constructed with differing shapes to optimize receiving capability at the cost of manufacturing complexity. For example,FIG.3Aillustrates using rectangular antenna elements31, which may be the simplest to design and manufacture.FIG.3Billustrates a spherical antenna section3which may be the most efficient and accurate of the antenna sections3. However, because of the difficulty of designing and manufacturing a spherical antenna section3(FIG.3B), a user may prefer to approximate a cube or sphere with rectangular antenna elements31, see, e.g.,FIG.3C.

For situations where directional detection is important, exemplary embodiments can use larger numbers of antenna elements to increase the accuracy of directional detection. For example, one can decrease the size of individual rectangular antenna elements and increase the number of total number of elements used such that the overall size of the antenna section stays constant while also increasing the measurement fidelity. For situations where directional detection is needed from specific directions, exemplary embodiments can be shaped with antenna elements to match the expected environment. For example, a hemispherical antenna section3can be used for surface-based systems because transmissions will only be received along or above the surface. For elevated operating environments (e.g., system mounted on a raised structure or aerial systems), a fully spherical antenna section3allows transmissions to be received from any direction. In these elevated operating environment embodiments, the layers of the transmission section can match the general shape such that the transmission section5only covers the expected angles of signal detection. For example, a hemispherical antenna section does not need refractive material below the spherical cap, so condensing the transmission section to a hemispherical shape can simply production and reduce material costs.

FIG.4illustrates an exemplary communication system1used in a simplex configuration with a plurality of transmitters41(three shown). In this configuration, system1receives signals from transmitters41through corresponding simplex connections43. Communication system1may be configured to receive transmissions from a plurality of angles (e.g., as shown inFIG.1) so that the position of transmitters41with respect to communication system1can vary.

FIG.5shows another exemplary communication system1with a combined simplex and duplex configuration with a plurality of transmitters41. In this configuration, communication system1can receive signals from transmitters41through corresponding simplex connections43. Communication system1may further be configured to receive transmissions from a plurality of angles (e.g., as shown inFIG.1) so that the position of transmitters41with respect to communication system1can vary. In addition, each embodiment of communication system1can be paired with a transmitter41to enable full duplex connections51between multiple communication systems1(two shown inFIG.5) to allow communication systems1to operate in conjunction with each other.

FIG.6illustrates yet another exemplary system1with a combined simplex43and duplex51configuration employing a plurality of transmitters41. In this configuration, communication system1can receive signals from transmitters41through corresponding simplex connections43. Communication system1may further be configured to receive transmissions from a plurality of angles (e.g., as shown inFIG.1) so that the position of transmitters41with respect to system1can vary. In addition, each communication system1can be paired with a transmitter41to enable duplex connections51between multiple communication systems1to allow communication systems1to operate in conjunction with each other. Each communication system1can independently receive transmissions from transmitters41so that in combination the communication systems1can provide a larger target/reception area.

FIG.7illustrates a plurality of exemplary communication systems1installed on platform71. As shown inFIG.7platform71may include an electronics section73in communication with a plurality of exemplary communication systems1(four shown). In exemplary embodiments, a plurality of communication systems1can be used in tandem allowing more precise communication and detection. Each communication system1can be configured to receive from a different field of view. In these embodiments, each communication system1can comprise non-spherical (i.e., hemispherical) antenna elements31because no single communication system1needs to detect signals from every direction. In exemplary embodiments, the plurality of communication systems1can be configured to receive signals from overlapping fields of view to ensure there are no blind spots or to provide redundant detection for improved accuracy. For example, the platform71can have vertically oriented systems1to provide detection around the entirely of platform71and can also have horizontally oriented systems1to provide redundant detection capabilities.

Electronics section73may include a variety of standard electronics (e.g., a processor, power source, etc., not shown for ease of illustration) in communication with at least one transmitter41(also not shown) to allow the communication systems1to operate with external systems outside of the platform71(e.g., additional platforms, ground stations, etc.) via duplex links51(not shown inFIG.7). Electronics section73can be electrically coupled to each communication system1by I/O lines (not shown for simplicity of illustration) to process signals and allow the communication systems1to communicate with each other. For mobile platforms (e.g., aerial vehicles, drones, etc.), signals detected and processed can trigger platform71responses (e.g., maneuvering or orienting the platform, landing procedures, etc.)

FIG.8illustrates a flowchart of an exemplary method800for manufacturing communication systems, according to the present invention. Method800may include providing801at least one antenna element31, at least one transmission medium, and input/output (I/O) lines21. In exemplary embodiments of method800, each of the at least one transmission medium can be a mirror, a lens, or a refraction medium. Method800may further include forming803an antenna section3comprising the at least one antenna element31. In exemplary embodiments, the at least one antenna element31can be oriented to face a particular direction. In exemplary embodiments, the at least one antenna element31can be made to have a variety of shapes (e.g., cuboids, spherical segments, spherical wedges, etc.) In exemplary embodiments having a plurality of antenna elements31, the antenna elements31can be arranged to form a particular shape when combined (e.g., cuboids forming a cube around an empty interior, or spherical wedges forming a sphere). Method800may further include optically coupling805the I/O lines21to the antenna section3. Each of the at least one antenna elements31can be configured to transmit signal info through the I/O lines21. Method800may further include coupling807the antenna section3to the transmission medium such that the transmission medium forms a transmission section5around the antenna section3. In exemplary embodiments, the transmission section5can be formed before any transmission medium is coupled to the antenna section3. In alternative exemplary embodiments, each transmission medium can be directly coupled to the antenna section3such that the transmission section5is built around the antenna section3. In at least some of the embodiments, the transmission medium can be additively manufactured around the antenna section3.

FIG.9Ais a cross-sectional (profile) view of an embodiment of an optical communication receiver100, according to the present invention. The embodiment of an optical communication receiver100may include a Lüneburg lens102configured to bend external free-space optical transmissions110from external transmitters120toward a photodetector104in communication with a processor106. As depicted inFIG.9A, the Lüneburg lens102may be spherical or hemispherical108in shape and thus capable of receiving and bending optical frequency light transmissions110impinging on its hemispherical surface108toward the sensor plane112of photodetector104. While not shown to scale, the incoming signal energy density210is depicted by bold lines inFIG.9A.

Operationally, the optical communication receiver100may be included in an optical receiver system, shown generally at arrow150, including multiple externally located optical transmitters120(three shown inFIG.9A) located at various sites near or distant from the optical communication receiver100with various angles relative to the optical communication receiver100. Each optical transmitter120may be configured to transmit signals at free space optic (FSO) visible light frequencies for reception at receiver100. The Lüneburg lens102bends the optical signals110towards a sensor plane112which forms an interface between the Lüneburg lens102and the photodetector104.

The Lüneburg lens102may be configured to bend the light from the optical transmissions110to hit a photodetector104behind the Lüneburg lens102. The Lüneburg lens102may be configured for operation in the visible spectrum according to a presently preferred embodiment. The Lüneburg lens102may be additively manufactured or formed using conventional techniques. It will be understood that the particulars of constructing a Lüneburg lens102for use with visible spectrum light suitable for use in the present invention falls within the knowledge of one of ordinary skill in the art. See e.g., Yokoulian, “Researchers confront optics and data-transfer challenges with 3D-printed lens”, News Bureau, University of Illinois Urbana-Champaign, Dec. 3, 2020, <https://blogs.illinois.edu/view/6367/1565551394>; Wallace, “3D-printed gradient-index Lüneburg lens is fabricated at optical wavelengths”, Laser Focus World, Dec. 3, 2020, <https://www.laserfocusworld.com/optics/article/14188413/3d-printed-gradient-index-luneburg-lens-is-fabricated-at-optical-wavelengths>; Babayr{hacek over (g)}it et al., “Analytical, numerical, and experimental investigation of a Luneburg lens system for directional cloaking”, Phys. Rev. A 99, 043831— Published 23 Apr. 2019; Zhao et al., “Three-dimensional Luneburg lens at optical frequencies”, Wiley Online Library, Laser & Photonics Reviews, <https://doi.org/10.1002/Ipor.201600051>; and Di Falco et al., “Luneburg lens in silicon photonics”, Optica Publishing Group, Optics Express Vol. 19, Issue 6, pp. 5156-5162 (2011), <https://doi.org/10.1364/0E.19.005156>. The contents of each of the five above-referenced technical articles are hereby incorporated by reference for all purposes as if fully set forth herein.

FIG.9Bis an exemplary plan view of exemplary incident light density from the transmitters120shown inFIG.9Aafter passing through a Lüneburg lens102and onto the photodetector104, according to the present invention. The incident light stimulates the photodetector104with its variable energy density (darker being higher density). This energy density detected by the photodetector104may then be digitized and processed in the processor106. More particularly,FIG.9Billustrates a rectangular sensor region130or map with x and y coordinates corresponding to incident light energy at each pixel. Still more particularly, three incoming signal densities210are shown inFIG.9B, though not necessarily to scale. It will be understood that the processor106may be any suitable digital signal processor, or microprocessor, whether custom designed, commercially available, or programmable, e.g., field programmable gate array (FPGA), application specific integrated circuit (ASIC), or as a component with other electronics on a printed circuit board (PCB), a computer system or other higher-order computational system. It will further be understood that the processor may be implemented along with any suitable software providing computer instructions for control of the signal processing for inbound or outbound optical signals consistent with the teachings of the present invention and that such hardware and software implementations fall within the knowledge of one of ordinary skill in the art and thus will not be further elaborated herein.

FIG.10is a three-dimensional (3D) depiction of an exemplary optical communication receiver100, according to the present invention. As depicted inFIG.10, optical communication receiver100may include a Lüneburg lens102stacked on top of a photodetector104, which in turn may be stacked on top of, and in communication with, processor106. Operationally, the Lüneburg lens102is configured to direct incident light onto photodetector104with the processor106for signal processing.

FIG.11illustrates exemplary energy density maps202,204,206and208depicting incident light signals ranging from none to three with overlap, according to the present invention. More particularly, map202in the upper left-hand corner ofFIG.11illustrates no signals. Map204in the upper right-hand corner ofFIG.11illustrates one exemplary signal210. Map206in the lower left-hand corner ofFIG.11illustrates two exemplary signals210. Finally, map208in the lower right-hand corner ofFIG.11illustrates three exemplary signals210. Again, each energy density map202,204,206and208may also be representative of the photodetector104sensor surface in an x-y plane. It will be understood that the darker the signal210, the higher the energy density in that location. The gradient of concentration of energy allows for delineation between multiple signals210present at the same time.

FIG.12is a block diagram of an exemplary full-duplex optical communication system200, according to the present invention. The illustrated embodiment of a full-duplex optical communication system200may include an optical communication receiver100as described herein in communication with any suitable optical transmitter160. It will be understood that communication system200may be used in the full-duplex51optical communications systems illustrated inFIGS.5and6by simply replacing the paired communication system1and transmitter41. It will be further understood that optical communication receiver100may be used in place of communication system1inFIGS.4,5and6, according to further embodiments of the present invention. It will also be understood that the particular communication platform upon which the inventive optical communication receiver100or communications system200is integrated is not limiting. Any suitable platform, whether stationary (e.g., building, tower, ground, etc.), aerial (e.g., drone, aircraft, etc.), or mobile surface-based (e.g., ground vehicle, watercraft, etc.) may be used to support the inventive optical communication receiver100or communications system200disclosed herein. Such platforms are well-known to those of ordinary skill in the art and thus will not be further detailed herein.

Having described particular embodiments of the communications receiver100, communications systems1and200and method800for manufacturing communication systems with reference to the drawings, more general embodiments of the present invention are described follows. An embodiment of an optical communication receiver is disclosed. The embodiment of an optical communication receiver may include a photodetector having a sensor plane. According to this embodiment, the photodetector may be configured to receive incident optical light signals and detect optical signal energy density corresponding to x-y locations along the sensor plane. The embodiment of an optical communication receiver may further include a Lüneburg lens adjacent to the photodetector, the Lüneburg lens configured to direct incident optical light signals onto the sensor plane of the photodetector. The embodiment of an optical communication receiver may further include a processor in communication with the photodetector configured for calculating power gradient of the optical signal energy density, isolating discrete signals, determining direction of the incident optical light signals and gathering information transmitted in the incident optical light signals.

According to another embodiment of the optical communications receiver, the Lüneburg lens may include an external surface shape that is spherical or hemispherical. According to yet another embodiment of the optical communications receiver, the Lüneburg lens may be tuned for visible spectrum light transmission. According to still another embodiment of the optical communications receiver, the Lüneburg lens may be formed of a continuous refractive medium. According to a particular embodiment, the refractive medium may include a gradient index lens having a refractive index that decreases radially from a center-most surface to the outer-most surface of the Lüneburg lens. According to another embodiment, the optical communication system, may further include an optical transmitter in communication with the processor, the optical transmitter configured to transmit outbound optical signals under processor control.

An embodiment of an optical communication system is disclosed. The embodiment of an optical communication system may include an optical receiver configured to receive inbound optical signals, the optical receiver comprising a Lüneburg lens. The embodiment of an optical communication system may further include a processor in communication with the optical receiver. The processor may further be configured for calculating power gradient of energy density of the inbound optical signals. The processor may further be configured for isolating discrete inbound optical signals, which may be overlapped. The processor may further be configured for determining the direction of the inbound optical light signals. The processor may further be configured for gathering information transmitted in the inbound optical light signals, i.e., decoding.

According to one embodiment of an optical communication system, the optical receiver may further include a photodetector having a sensor plane. According to this embodiment, the photodetector may be disposed adjacent to the Lüneburg lens and configured to receive the inbound optical light signals transmitted through the Lüneburg lens. According to this embodiment, the photodetector may further be configured to detect optical signal energy density corresponding to x-y locations along the sensor plane. According to yet another embodiment of an optical communication system, the Lüneburg lens may be tuned for visible spectrum light transmission. According to still yet another embodiment of an optical communication system, the Lüneburg lens may be formed of a continuous refractive medium. According to one particular embodiment of an optical communication system, the refractive medium may include a gradient index lens having a refractive index that decreases radially from a center-most surface to the outer-most surface of the Lüneburg lens. According to a couple additional embodiments of an optical communication system, the Lüneburg lens may have an external surface shape that is either spherical or hemispherical.

An embodiment of a communication platform is disclosed. The embodiment of a communication platform may include at least one optical communication system. Each embodiment of the at least one optical communication system may further include an optical receiver configured to receive inbound optical signals. The optical receiver may further include a Lüneburg lens. Each embodiment of the at least one optical communication system may further include a processor in communication with the optical receiver. The processor may further be configured for calculating power gradient of energy density of the inbound optical signals. The processor may further be configured for isolating discrete inbound optical signals. The processor may further be configured for determining direction of the inbound optical light signals. The processor may further be configured for gathering information transmitted in the inbound optical light signals or decoding.

According to one embodiment of a communication platform, the at least one optical communication system may further include an optical transmitter in communication with the processor and configured to transmit outbound optical signals under processor control. According to another embodiment of a communication platform, the optical receiver may further include a photodetector having a sensor plane. According to this particular embodiment, the photodetector may be adjacent to the Lüneburg lens and configured to receive the inbound optical light signals transmitted through the Lüneburg lens. According to this particular embodiment, the photodetector may further be configured to detect optical signal energy density corresponding to x-y locations along the sensor plane. According to a couple additional embodiments of the optical communication platform, the Lüneburg lens may have an external surface shape of either spherical or hemispherical.

According to another embodiment of a communication platform, the Lüneburg lens may be formed of a continuous refractive medium. According to yet another embodiment of a communication platform, the refractive medium may be a gradient index lens having a refractive index that decreases radially from a center-most surface to the outer-most surface of the Lüneburg lens. According to still yet another embodiment, the communication platform may be an aerial vehicle. According to one embodiment, the communication platform may further include a ground mounted tower, wherein the at least one communication system is coupled to an upper section of the tower.

According to an illustrative embodiment of the present disclosure, a communication system comprises a transmission section surrounding an antenna section. The transmission section can be made of concentric layers of lens elements, mirror elements, or refraction medium. The layers allow incoming electromagnetic radiation (EMR) to be directed to the antenna section through reflection or refraction. The antenna section can be made of a plurality of antenna elements such that each antenna element detects incoming EMR signals from different angles of origin even when the signals are received simultaneously. Signal information can then be sent to other devices through input/output (I/O) lines coupled to the antenna section.

According to a further illustrative embodiment of the present disclosure, an antenna section can be created with a variable number and size of individual antenna elements. Exemplary embodiments can include a larger number of antenna elements to increase accuracy of signal detection and direction finding. Antenna elements can be made in a variety of sizes to improve accuracy or manufacturing simplicity.

According to a further illustrative embodiment of the present disclosure, communication systems can be mounted onto a stationary or mobile platform. A plurality of communication systems can be used to provide detection coverage of specific angles and can include overlapping coverage. Coverage is not needed for angles where signal detection is not wanted or expected.

From the above description of the embodiments of the communications receiver100, communications systems1and200and method800for manufacturing communication systems, it is manifest that various alternative structures may be used for implementing features of the present invention without departing from the scope of the claims. The described embodiments are to be considered in all respects as illustrative and not restrictive. It will further be understood that the present invention may suitably comprise, consist of, or consist essentially of the component parts, method steps and limitations disclosed herein. The method and/or apparatus disclosed herein may be practiced in the absence of any element that is not specifically claimed and/or disclosed herein.

While the foregoing advantages of the present invention are manifested in the detailed description and illustrated embodiments of the invention, a variety of changes can be made to the configuration, design and construction of the invention to achieve those advantages. Hence, reference herein to specific details of the structure and function of the present invention is by way of example only and not by way of limitation.