Abstract: A second transceiver (22) includes a guide light source (22c), a photorefractive crystal (22a), and a frequency control unit (22e). The guide light source (22c) emits guide light (Y3). A double phase conjugate mirror (22m) is formed in a crystal (22a) by scattering of reference signal light (Y1), which has a frequency different from that of the guide light and is incident on the crystal via space (15) after being transmitted from a first transceiver (21) which is a transceiver on the other side, and the guide light that is incident on the crystal in a reverse direction to that of the reference signal light. A frequency control unit (22e) couples the reference signal light emitted from the crystal (22a), which is phase-conjugate light of the guide light generated by the mirror (22m), to an optical fiber (13b).

Abstract: A light-receiving device includes: a light guide plate that is a transparent member having, as main surfaces, a first surface and a second surface facing each other and has an emission end formed on at least one end portion of the light guide plate; a wave plate that is disposed on the first surface of the light guide plate and converts an optical signal of circularly polarized light into linearly polarized light; a hologram layer that is disposed on the second surface of the light guide plate and guides a traveling direction of the optical signal converted into the linearly polarized light toward the emission end of the light guide plate; and a light receiver that receives the optical signal emitted from the emission end of the light guide plate and converts the received optical signal into an electrical signal.

Abstract: A terminal (100) for optical communication by laser signals including a matrix image sensor used as a tracking and acquisition detector (2). The matrix image sensor is used simultaneously to check that a portion of the laser signals received by the terminal are injected into an optical fibre (1). A spectral filter element (22) is associated with the matrix image sensor to allow such a combination of functions.

Abstract: A receiver for free-space optical communication includes a beam splitter, an imaging unit, a specifying unit, a light-receiving unit, and a controller. The beam splitter splits incident light into first and second light beams travelling in different directions. The imaging unit captures an image of the first light beam. The specifying unit extracts a signal light beam from the image of the first light beam and specifies a position of the signal light beam in the image. The light-receiving device receives the second light beam. The controller controls a blocker on the basis of the position of the signal light beam to allow only a limited portion of the second light beam to enter the light-receiving device and prevent a remaining portion of the second light beam from entering the light-receiving device. The limited portion of the second light beam includes the signal light beam.

Abstract: Novel tools and techniques are provided for implementing visual impairment detection for free-space optical communication (“FSOC”) systems. In various embodiments, a computing system might receive, either from a camera or from a database, images (and/or videos) of an optical field of view (“FOV”) of the camera, the optical FOV comprising an optical beam(s) of a first FSOC system; might autonomously analyze the captured images (and/or videos) to determine whether an object(s) is moving within proximity to an optical beam(s) of the first FSOC system, to perform at least one of reactive learning or proactive learning regarding potential interruption of the optical beam(s) of the first FSOC system, and/or to determine one or more preventative measures to prevent interruption of the optical beam(s) of the first FSOC system; and might autonomously initiate one or more first tasks and/or the one or more preventative measures, based on the analysis.

Abstract: Methods, machines and systems for processing information are disclosed in which waves containing information select locations for processing (46). Associations between information containing waves may be made and recalled. In some embodiments information containing waves or sequences may be output as visual, auditory, tactile, motion, data or other forms. Software embodiments of the described mechanism are also included.

Abstract: An optical system (100) comprising: a transmitter module (102) configured to transmit a sequence of optical pulses (300), each optical pulse in the sequence (300) having a different magnitude to each other optical pulse in the sequence (300); a receiver module (104) comprising one or more optical signal detectors, the receiver module (104) configured to receive the sequence of optical pulses (300) transmitted by the transmitter module (102); and one or more processors (110) configured to process the sequence of optical pulses received by the receiver module (104) to select an optical pulse from the received sequence of optical pulses (400) based on one or more predetermined criteria. The one or more predetermined criteria include a criterion that the selected optical pulse does not saturate the one or more optical signal detectors.

Abstract: Novel tools and techniques are provided for implementing visual impairment detection for free-space optical communication (“FSOC”) systems. In various embodiments, a computing system might receive, either from a camera or from a database, images (and/or videos) of an optical field of view (“FOV”) of the camera, the optical FOV comprising an optical beam(s) of a first FSOC system; might autonomously analyze the captured images (and/or videos) to determine whether an object(s) is moving within proximity to an optical beam(s) of the first FSOC system, to perform at least one of reactive learning or proactive learning regarding potential interruption of the optical beam(s) of the first FSOC system, and/or to determine one or more preventative measures to prevent interruption of the optical beam(s) of the first FSOC system; and might autonomously initiate one or more first tasks and/or the one or more preventative measures, based on the analysis.

Abstract: A directional free-space optical communication system includes a source device including a laser diode and an endpoint device including a photodiode. The endpoint device and the source device also include an adjustable optics subsystem that increases both angular and positional offset tolerance between the source device and the endpoint device.

Abstract: Optical communication with a remote node comprises: transmitting at least one optical beam to the remote node; receiving at least a portion of at least one optical beam from the remote node; providing intensity information based on one or more signals from one or more optical detector modules in an array of optical detector modules detecting the portion of the optical beam received from the remote node; and controlling at least one optical phased array to steer the optical beam transmitted to the remote node based on intensity information received from the remote node.

Abstract: Embodiments are directed to systems and methods for utilizing aircraft cockpit and cabin lighting to provide both power and data transmission to occupants. Data and power may be transmitted on non-visible and/or visible spectrums. The visible light may be used independently for aircraft illumination. Data for the cockpit allows for quick upload and download of flight planning and maintenance data to an electronic flight bag. The electronic flight bag may also be able to receive power from cockpit and cabin lighting during flight.

Abstract: A signal processing device combines a plurality of received signals, and includes: a phase reference signal selection means for selecting a signal serving as a phase reference from among the plurality of received signals on the basis of the quality of the plurality of received signals; a relative phase calculation means for obtaining information about the relative phases of the plurality of received signals before the combining; a phase compensation means for performing relative phase compensation on each of the plurality of received signals on the basis of the relative phases; and a phase correction means for calculating a phase correction amount based on the relative phase information and performing phase correction on the received signals, wherein when switching occurs in the selected phase reference signal, the phase correction amount is changed by as much as the relative phase difference between the phase reference signals before and after the switching.

Abstract: High power, high speed VCSEL arrays are employed in unique configurations of arrays and sub-arrays. Placement of a VCSEL array behind a lens allows spatial separation and directivity. Diffusion may be employed to increase alignment tolerance. Intensity modulation may be performed by operating groups of VCSEL emitters at maximum bias. Optical communications networks with high bandwidth may employ angular, spatial, and/or wavelength multiplexing. A variety of network topologies and bandwidths suitable for the data center may be implemented. Eye safe networks may employ VCSEL emitters may be paired with optical elements to reduce optical power density to eye safe levels.

Abstract: Systems, devices, and methods for underwater communications are disclosed. In particular, the present invention relates to laser-mediated underwater communications, in which one or more laser signals transmit encoded information from a transmitter to a receiver. Accordingly, at least one embodiment of the invention includes an underwater transmitter node that sends information to an underwater receiver node using one or more lasers. The one or more lasers may be focused on to the underwater receiver node using a lens, telescope, or the like. The one or more lasers may additionally have a wavelength in the blue-green portion of the visible spectrum, including specifically, for instance, 450 nm, thereby enabling the one or more lasers to transmit effectively underwater. In additional embodiments of the invention, the information transmitted between the underwater transmitter node and the underwater receiver node is an encoded digital transmission.

Abstract: Many free-space optical (FSO) communications systems use pointing, acquisition, and tracking (PAT) systems to align the transmit and receive apertures for efficiently coupling received light to a detector. Conventional PAT systems divert energy from the communications receiver to a photodiode array for measuring tilt in the focal plane. Unfortunately, diverting energy from communications to PAT reduces SNR and sensitivity for communications. The PAT terminal disclosed here determines tilt angle without diverting energy from the communications receiver. It tracks the power in different spatial modes and uses that power distribution to determine tilt information for PAT. It does this with a passive mode converter, such as a photonic lantern, that maps power in each spatial mode at the receive aperture to a different single-mode output.

Abstract: A phase modulation active device and a method of driving the same are provided. The method may include configuring, for the phase modulation active device including a plurality of channels that modulate a phase of incident light, a phase profile indicating a phase modulation target value to be implemented by the phase modulation active device; setting a phase limit value of the phase modulation active device; generating a modified phase profile based on the phase profile by modifying the phase modulation target value, for at least one channel from the plurality of channels that meets or exceeds the phase limit value, to a modified phase modulation target value that is less than the phase limit value in the phase profile; and operating the phase modulation active device based on the modified phase profile. Thus, improved optical modulation performance may be achieved.

Abstract: A method for transmitting a binary data signal to or from a satellite via an optical feeder link, wherein an optical transmitting interface carries out the following steps multiplexing binary physical layer frames which are associated with a plurality of carriers or a plurality of beams in a satellite communication system into a single bit stream, inserting a binary physical layer frame identification sequence upstream of each physical layer frame, wherein the physical layer frame identification sequence comprises: a unique binary synchronization sequence, a binary beam index sequence, a binary carrier frequency index sequence, a binary baud rate index sequence, a binary roll-off factor index sequence, a binary modulation index sequence.

Abstract: The present invention provides a free space optical communication system that uses orthogonal modes of aberration in a laser beam as means for encoding the information. The system comprises a transmission station which transmits the user defined information in terms of the amplitudes of certain orthogonal aberration modes present in the transmitted beam. The beam then travels through free space before it reaches the receiving station. The receiving station comprises a high speed wavefront sensor of light beams. The wavefront sensor measures the amplitudes of various orthogonal aberration modes present in the incident beam at different instants of time. The amplitudes of the orthogonal modes at a certain regular time interval are then used to extract the user information.

Abstract: A wireless hands-free portable headset computer with a micro display arranged near but below a wearer's eye in a peripheral vision area not blocking the wearer's main line of sight. The headset computer can display an image or portions of an image, wherein the portions can be enlarged. The headset computer also can be equipped with peripheral devices, such as light sources and cameras that can emit and detect, respectively, visible light and invisible radiation, such as infrared radiation and ultraviolet radiation. The peripheral devices are controllable by the wearer by voice command or by gesture. The headset computer also can be broken down into component parts that are attachable to another article worn by an individual, such as a helmet or respirator mask.

Abstract: Disclosed herein are a dual-mode device operating in a visible light communications mode and a wireless network communications mode, and a method performed by the device. The visible light communications device includes a wireless network communications unit including a fixed identifier and performing communications based on a wireless protocol, a visible light transmitting unit transmitting the fixed identifier using a visible light communications protocol, and a controller (control unit) controlling the visible light transmitting unit so that it selectively transmits the fixed identifier using the visible light communications protocol depending on whether the wireless network communications unit is connected to a wireless network.

Abstract: A system includes an optical transceiver configured to transmit/receive at least one optical feed and a beam separator configured to separate the optical feed into a plurality of optical beams, and spatially combine the optical beams into the optical beam. The system also includes a dichroic mirror optically coupled to the beam separator and configured to reflect the optical beams, and allow beacon signals to pass therethrough. A position sensitive detector of the system optically couples to the dichroic mirror and is configured to sense an incidence position of each beacon signal allowed to pass through the dichroic mirror, and output a position error for each optical beam based on the sensed incidence positions. The system also includes a multi-axis optical steering system configured to direct each optical beam based on the corresponding position error outputted from the position sensitive detector and a corresponding transmit/receive target.

Abstract: Embodiments are directed to systems and methods for imaging an object obscured by a distorted medium. The embodiments include an object emitting electromagnetic energy due to rapid heating. The electromagnetic energy for the object passes through the distorted medium. Embodiments combine an adaptive optics system, an adaptive holographic plates/filters system, an optical based multi-wavelength sensor system, and a phase diversity processor system to provide a corrected image of the object obscured by the distorted medium.

Abstract: Aspects are generally directed to an inter-satellite communication system and method of communicating between satellites. In one example, an inter-satellite communication system includes a first satellite transceiver having an entrance aperture, and a non-mechanical beamsteering device configured to steer a first beam of encoded optical data over a field of view thereof. The first satellite transceiver may include coarse steering optics configured to extend a field of regard of the non-mechanical beamsteering device. During a transmit mode, the coarse steering optics are positioned to transmit the first beam of encoded optical data through the entrance aperture in a direction of a second satellite transceiver. The first satellite transceiver may also include a beam splitter positioned, during a receive mode, to receive a second beam of encoded optical data from the second satellite transceiver and direct the second beam of encoded optical data to an optical sensor.

Abstract: A system includes a first optical communication interface and a second optical communication interface optically coupled via a free-space communication channel. The interfaces are spaced at variable distances. Each interface includes an optical source to provide a beam of electromagnetic energy and an optical receiver to receive the beam to bi-directionally communicate with the other interface via the channel. The first optical communication interface may be coupled to a sub-chassis. The second optical communication interface may be coupled to a device frame. The device frame may be movably coupled to the chassis. Communication may utilize multi-input, multi-output processing configured by a calibration matrix. A shutter may be positioned to receive the beam or be positioned clear of the beam depending on the distance between the interfaces.

Abstract: A system of optical power and data transfer includes an optical emitter to emit a data signal and a power signal along a common path. The system also includes a demultiplexer coupled to receive the data signal and the power signal, where the demultiplexer includes a first output coupled to output the data signal and a second output coupled to output the power signal. An optical receiver is optically coupled to the first output to receive the data signal and convert the data signal into electrical data. A power converter is optically coupled to the second output to receive the power signal and to convert the power signal into electrical power to power operation of other circuitry.

Abstract: Adjustment of an optical component of a device includes determining of at least one derivative of coupling efficiency of the optical component as a function of parameters used for control of a steering function of the optical component. At least one oscillating component is induced into the parameters for the determining. The adjustment of the optical component is based on the determined at least one derivative.

Abstract: Described herein is a space based subsystem of a satellite, and methods for use therewith, for receiving an RF uplink feeder beam and in dependence thereon producing one or more optical ISL beams for transmission to one or more other satellites. The subsystem can include an antenna to receive an RF feeder uplink beam and produce an RF signal therefrom. The subsystem can also include, inter alia, RF components, local oscillator(s), lasers, EOMs, a WDM multiplexer, an optical amplifier and transmitter optics. Such components can be used to convert the RF signal to one or more ISL beams for transmission to one or more other satellites. Where RF frequencies of optical data signals output by the EOMs are within the same RF frequency range within which the other satellite(s) transmit RF service downlink beams, there is an elimination of any need for the other satellite(s) to perform frequency conversions.

Abstract: The present invention discloses a data transmission method. The method includes: receiving, by a data processing apparatus, at least two data flows transmitted from at least two remote base stations among multiple remote base stations, aggregating the at least two data flows into one flow of output data, and transmitting the output data to a central site device; or receiving, by the data processing apparatus, one flow of synthetic input data transmitted from the central site device, restoring the synthetic input data to at least two data flows before synthesis, and transmitting the restored at least two data flows to corresponding remote base stations.

Abstract: An optical input/output device includes a phase modulator element and an optical element. The phase modulator element includes a plurality of pixels arranged in a matrix and is configured to change an optical phase of signal light by applying a driving signal corresponding to a phase pattern. The optical element is configured to convert a direction of exit of the signal light so as to irradiate each pixel with the signal light from the input port. A pattern generator unit includes superimposing means for superimposing a periodic phase pattern having a predetermined period in at least one direction in a plane of the phase modulator element, and means for controlling an amplitude of the periodic phase pattern. The signal light is diffracted to a position according to the period of the superimposed periodic phase pattern, so that light intensity of the signal light is dispersed.

Abstract: A free-space optical (FSO) transceiver can include a link predictor configured to estimate conditions for an FSO link over a window of time in the future. The FSO transceiver can also include a scheduler configured to assign outgoing packets to blocks of time in the window of time based on quality of service (QoS) parameters of each of the outgoing packets and on conditions in each block of time in the window of time.

Abstract: Systems and methods of electronic wavefront correction are disclosed. An example method receiving an optical signal representing a wavefront traveling along a plurality of propagation paths, and electronically correcting distortion in the wavefront. An example apparatus includes an receiver and an electronic wavefront corrector. The receiver is configured to coherently receive an optical signal representing a wavefront traveling along a plurality of propagation paths. The electronic wavefront corrector is configured to correct phase distortion in the wavefront.

Abstract: Methods and systems are described for determining and providing instructions for manual adjustment of a tilt angle of a radio frequency/free space optical transceiver system. Specifically, these instructions are provided for adjusting a tilt angle of a transceiver system using a tilt adjustment so that the transceiver system is approximately at a center of a range of motion of a gimbal assembly. A user interface in communication with a computing system of the local transceiver system provides instructions so that the above-described adjustments are implemented accurately and precisely. This tilt adjustment improves the reliability of the communication network because the gimbal assembly is able adjust the position of the transceiver system during relative movement between the transceivers system, thus maintaining the link despite the relative movement.

Abstract: A method and apparatus for establishing a terahertz link using a multi-element lens array that comprises a liquid lens are disclosed. For example, the method receives detected terahertz signals from one or more detectors, where a liquid lens is deployed with each of the one or more detectors. The method determines, for each of the detected signals, if the detected signal is out of focus, and applies a corrective voltage to each liquid lens that corresponds to a detected terahertz signal that is out of focus, wherein the corrective voltage adjusts a focus of the detected signal. The method measures a signal-to-noise ratio of the detected signals, and establishing a terahertz link via at least one of the detected terahertz signals with a highest signal-to-noise ratio.

Abstract: An approach is provided that uses diversity to compensate fading of free-space optical (FSO) signals propagating through an environment characterized by atmospheric scintillation. One embodiment involves collecting at least one FSO beam, demultiplexing the beam by wavelength into at least two sub-beams, detecting each sub-beam to produce an electrical output therefrom, and recovering a signal using complementary information from at least two of the electrical outputs. Another embodiment involves collecting the FSO beam onto an array of spatially separated sub-apertures, detecting the light entering each sub-aperture to produce an electrical output therefrom, and recovering a signal using complementary information from at least two of the electrical outputs. This second embodiment enables both electronic adaptive processing to coherently integrate across the sub-apertures and in the case of multiple transmit apertures a free space optical Multiple Input Multiple Output (MIMO) system.

Abstract: Methods and apparatus related to the detection of low-rate visible light communication (VLC) signals and the recovery of information communicated by the VLC signals are described. Various methods and apparatus are well suited for embodiments in which a device, e.g., a smartphone, including a camera which uses a rolling shutter. The rolling shutter facilitates the collection of different time snapshots of a received low rate time varying VLC signal with different pixel rows in the image sensor of a frame corresponding to different time snapshots. In some embodiments, demodulation is used to recover and identify a single tone being communicated in a frame from among a plurality of possible alternative tones that may be communicated, each different tone corresponding to a different set of information bits.

Abstract: Remote control signal detection systems and methods are operable to compensate detected infrared energy to identify an infrared energy communication signal emitted by a remote control. An exemplary embodiment detects first infrared energy, wherein the infrared energy communication signal is absent in the first infrared energy; determines compensation based on the first infrared energy; detects second infrared energy, wherein the infrared energy communication signal is present in the second infrared energy; and compensates the second infrared energy based on the determined compensation.

Abstract: A VLC (Visible Light Communication) modulation system and method thereof, which includes a visible light generating device and a visible light receiving device. The visible light generating device includes a visible light emitting module and an arbitrary waveform generator. The arbitrary waveform generator further includes a first finite impulse response filtering unit, a pre-distortion amount control unit, and a second finite impulse response filtering unit.

Abstract: An apparatus and a method for providing synchronized data by using visible light communication includes, receiving a synchronization channel from a mobile communication base station using a specific mobile communication network, by a Light Emitting Diode (LED) lighting; analyzing the received synchronization channel, and extracting a synchronization signal for synchronizing the LED lighting with at least one LED lighting adjacent to the LED lighting; selecting a specific time slot of the synchronization signal based on IDentifications (IDs) of the LED lightings; and including a data frame of the LED lighting in the specific time slot, and transmitting the specific time slot, which includes the data frame of the LED lighting, to a mobile terminal.

Abstract: The embodiments provide an inverse channel apparatus and transmitter, receiver and system containing the apparatus; wherein the inverse channel apparatus comprises: an inverse nonlinear calculating unit configured to perform nonlinear additive calculation and nonlinear multiplicative calculation on input signals, so as to obtain signals containing nonlinear damage of the input signals on at least one polarization state; and an inverse linear calculating unit configured to calculate signals containing nonlinear damage and linear damage of the input signals on at least one polarization state according to the signals containing nonlinear damage of the input signals on at least one polarization state and a linear function of a channel.

Abstract: A system and method in the field of free space optical communications (FSOC) for overcoming atmospheric-induced spatial optical signal variations operates within each of two FSOC terminals that make up a bi-directional FSOC link, with each terminal providing the rapid adaptive beam path method over a much wider field of view than typically used for adaptive optical techniques. Each terminal uses a real-time adaptive beam-steering technique that continuously measures optical power and optical power gradients by the receiver optical detectors; this data is sent to a control system that automatically responds by re-aligning the optical system accordingly by maximizing the optical signal power measured by the optical power receiving detector.

Abstract: A system and a method are disclosed for generating an infrared signal on a mobile device. The infrared signal is generated on a mobile device by generating a bitstream based on information to be transmitted as an infrared signal. The bitstream is modulated and output on a bus to an infrared-emitting diode. The bitstream is processed in a software layer configured on the computing device, enabling the computing device to generate and process signals without additional hardware configured on the device.

Abstract: A free space optical communications link node 10 comprising transmitter apparatus 12 comprising a first optical transmitter 14, arranged to transmit high priority traffic on a first upstream optical signal having a first wavelength and at a first optical signal power, and a second optical transmitter 16 arranged to transmit low priority traffic on a second upstream optical signal having a second wavelength, different to the first wavelength, and at a second optical signal power. The node 10 further comprises receiver apparatus 18 comprising a first optical amplifier 20 arranged to receive and amplify a first downstream optical signal having a third wavelength and carrying high priority traffic and a second downstream optical signal having a fourth wavelength, different to the third wavelength, and carrying low priority traffic.

Abstract: A method, apparatus, and a non-transitory computer readable storage medium for supporting visible light communication (VLC) exchanges bitmaps for capabilities field exchange in a media access control (MAC) layer during link establishment and association with other VLC-enabled devices. An aggregation bitmap is generated to indicate whether a visible light communication (VLC) transmitter of a first device uses at least one aggregated band that comprises multiple active frequency bands. The aggregation bitmap is transmitted in a capabilities information exchange (CIE) signal to a second device. A guard bitmap that identifies a set of guard frequency bands is also generated and transmitted in the CIE signal. Each guard frequency band indicates leakage transmission from the VLC transmitter.

Abstract: A free space optical communication system (100) and method including: several optical beam expanders (414) for receiving incoming optical signals from ground sites and neighboring satellites; several optical preamplifiers (412) for preamplifying the received optical signals; one or more optical main amplifiers (404) for amplifying the preamplified optical signals; and an optical switch (408) for directing respective amplified optical signals to respective destinations via a respective optical beam expander. The respective amplified optical signals are inputted to a respective optical beam expander (414) for transmission to said respective destinations, as outgoing optical signals.

Abstract: A transmission apparatus of a wireless light communication system using an illumination light source can maximize a rate of data transmission while maintaining a brightness adjusting function of the illumination light source. The transmission apparatus includes a dimming level input unit which receives a dimming level of the illumination light source as an input, a coder which codes original data and outputs the coded data, a dimming coder which checks the dimming level input to the dimming level input unit, generates a symbol-codeword table corresponding to the dimming level, and dimming-codes the data output from the coder, a line coder which converts the data diming-coded by the dimming coder into pulse signals.

Abstract: A lighting system includes light fixtures not in communications with and not synchronized with one another, and one or more light sensors. Each light fixture separately emits data encoded visible light including light fixture information encoded therein in a manner that avoids visually perceptible flicker and enables light fixture information emitted by one light fixture to be distinguished from light fixture information emitted by other light fixtures. The light fixture information is encoded into data encoded visible light such that a difference between different levels of the data encoded visible light is indicative of an illumination capability of the light fixture and such that visually perceptible flicker is avoided. Each light sensor separately receives portions of data encoded light visible light emitted by multiple light fixtures and separately determines the identity of and the maximum and present illumination contributions for each light fixture.

Abstract: A wireless communications link comprising an RF link and a free space optics (FSO) link, a switch, an RF signal monitoring apparatus, an optical signal monitoring apparatus, alarm apparatus and a controller. The switch operates in a normal mode to aggregate the links to form a link aggregation group and to route traffic on the link aggregation group, a first protection mode to route traffic on the FSO link, or a second protection mode to route traffic on the RF link. The controller is arranged to receive an alarm signal and to generate and transmit a control signal to cause the switch to operate in the first protection mode when a first alarm signal is received, the second protection mode when a second alarm signal is received, and the normal mode when an indicator is received indicating that both signal quality parameters are above their threshold values.

Abstract: A free space optical communication system (100) and method including a constellation of several satellites (102). Each of satellites including: several inter-satellite optical telescopes (204) for optical communication with multiple neighboring satellites, each inter-satellite optical telescope is capable of adjusting its elevation angle; and several up/down link optical telescopes (206) for optical communication with multiple ground sites. As the constellation passes a given ground site, some of the up/down-link telescopes of a given satellite are configured to track at least two respective ground optical telescopes of the given ground site and send data to the ground optical telescope with the clearest line of sight to the given satellite. Moreover, each of the satellites includes optical circuitry (208, 210, 212, 216) for optically processing and switching incoming and outgoing optical signals without converting the optical signals into electrical signals.

Abstract: A system for open space data communication comprising a transmitting device and an optical receiver using multiple varying levels of emitted radiation output. The transmitting device includes multiple emitter groups that are capable of being switched on and off and each of which can be activated in parallel to emit fixed, varying radiation outputs. A total radiation output emitted by the transmitting device is defined by a sum of the emitted radiation outputs of the emitter groups, wherein to transmit a bit vector (b0 . . . bn) an emitter group assigned to a most significant bit (b0) emits a maximum radiation output Pmax and emitter groups assigned to the less significant bits (b1 . . . bn) of the bit vector emit radiation outputs: Px=Pmax/2x where x=1 . . . n.

Abstract: The present disclosure provides electrical domain suppression of linear crosstalk in optical communication systems using single-carrier implementations. This electrical domain suppression applies spectral shaping in the electronic radio frequency (RF) domain. Advantageously, spectral shaping in the electronic RF domain transfers system complexity from the bulk optical domain into the highly integrated CMOS (or equivalent) domain. The spectral shaping can include electronic circuitry including an electrical filtering block and a signal linearization block prior to optical modulation. The electrical filtering block suppresses coherent interference terms and can include an RF-domain low pass filter. The signal linearization block linearizes modulator response to compensate spectral regrowth due to nonlinear mixing in the modulator.