A dual-mode imaging receiver (DMIR) can acquire and maintain SOA free-space optical communication (FSOC) links without a precision mechanical gimbal. Unlike other FSOC technologies, a DMIR can operate without precise spatial alignment and calibration of the transmitter's or receiver's spatial encoders (precision pointing) in static (fixed point to point) geometries. Instead, a DMIR uses electronic receive beam selection to acquire and track transmitters with coarse mechanical pointing and a single aperture. And because the DMIR can operate with just one aperture, it does not need a beacon at the transmitter since it does not transition from a wide field-of-view acquisition aperture to a narrow field-of-view detection and decoding aperture even in dynamic geometries.

Traditional satellite-to-earth data transmission systems are constrained by inefficient relay schemes and/or short-duration data transfers at low data rates. Communication systems described herein achieve extremely high burst rate (e.g., 10 Gbps or greater) direct-to-Earth (DTE) data transmission over a free-space optical link between a spacecraft and a remote terminal, which may be a ground terminal or another space terminal. The optical link is established, for example, when the remote terminal is at an elevation of 20? with respect to a horizon of the remote terminal. In some embodiments, a data transmission burst contains at least 1 Terabyte of information, and has a duration of 6 minutes or less. The communication system can include forward error correction by detecting a degradation of a received free-space optical signal and re-transmitting at least a portion of the free-space optical signal.

An optical receiver may include a unitary transformation operator to receive an n-symbol optical codeword associated with a codebook, and to perform a unitary transformation on the received optical codeword to generate a transformed optical codeword, where the unitary transformation is based on the codebook. The optical receiver may further include n optical detectors, where a particular one of the n optical detectors is to detect a particular optical symbol of the transformed optical codeword, and to determine whether the particular optical symbol corresponds to a first optical symbol or a second optical symbol. The optical receiver may also include a decoder to construct a codeword based on the determinations, and to decode the constructed codeword into a message using the codebook. The optical receiver may attain superadditive capacity, and, with an optimal code, may attain the Holevo limit to reliable communication data rates.

In order to increase a compensation range for Doppler shift compensation, this digital signal processing circuit is provided with a Doppler shift compensation unit which, on the basis of a sample sequence signal which is oversampled at N (where N is an integer at least equal to 2) times a symbol rate and includes a central sample corresponding to the timing at a symbol center, and a transition sample corresponding to the timing of a symbol transition, finds a Doppler shift amount included in the sample sequence signal and performs Doppler shift compensation. The Doppler shift compensation unit includes a symbol determining unit which performs a symbol determination with respect to the central sample and a determination with respect to the transition sample. The Doppler shift compensation unit switches between these determinations for each corresponding sample and performs said determinations in order to obtain a phase difference and thereby detect the Doppler shift amount.

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.

A mobile device includes an image sensor separated from a processing component by an open space. The image sensor includes one or more light source modules and the processing component includes one or more light sensors aligned with the one or more light source modules. Image data from the image sensor may be transmitted to the processing component via light signals exchanged between the one or more light source modules and the one or more light sensors. In some embodiments, light signals transmitted between one or more light source modules of an image sensor and one or more light sensors of the processing component are used to determine positional and angular data about the image sensor.

An optical tracking system may include optical sensors (e.g., infrared (IR) cameras) coupled with illuminators (e.g., IR light-emitting diodes (LEDs)). The optical tracking system may track an object having retro-reflective markers. The light from the illuminators may be reflected by the retro-reflective markers and detected by the optical sensors. In certain cases, the object may include emitters (e.g., IR LEDs) such that active light emitted from the object is directly detected by the optical sensors. The optical sensors generate data based on detected light and send the data to a controller. The controller may compute position data (e.g., indicative of a relative 2D position between the object and the optical sensors). The controller may send the position data to the object optically (e.g., using IR light).

Systems and methods are described for transmitting information optically. For instance, a system may include an optical source configured to generate a beam of light. The system may include at least one modulator configured to encode data on the beam of light to produce an encoded beam of light/encoded plurality of pulses. The system may include a spectrally-equalizing amplifier configured to receive the encoded beam of light/encoded plurality of pulses from the at least one modulator and both amplify and filter the encoded beam of light/encoded plurality of pulses to produce a filtered beam of light/filtered plurality of pulses, thereby spectrally equalizing a gain applied to the encoded beam of light. In some cases, the system may slice the beam of slight, to ensure a detector has impulsive detection. In some cases, the system may include a temperature controller to shift a distribution curve of wavelengths of the optical source.

A method for wireless data transmission between a first communication device and a second communication device, wherein the first communication device acts as a data source and the second communication device acts as a data sink, includes: splitting, by the data source, data to be transmitted from the data source to the data sink into a carrier signal for a radio channel and an optical carrier signal by modulating the carrier signals; transmitting the data via a hybrid transmission path from the data source to the data sink by simultaneously transmitting some of the data via the radio channel and some of the data via a wireless optical direct channel; and merging, by the data sink, via a demodulation process, the data transmitted via the radio channel and the data transmitted via the wireless optical direct channel.

Optical communication systems and methods using coherently combined optical beams are disclosed. A representative system includes a first mirror having a first actuator for adjusting a position of the first mirror in a path of a first optical beam and a first optical detector for receiving light reflected from the first mirror. The system also includes a second mirror having a second actuator for adjusting a position of the second mirror in a path of a second optical beam and a second optical detector for receiving light reflected from the second mirror. The system includes an interferometer for measuring an interference between the first and second optical beams and a third optical detector for receiving light from the second interfered optical beam. Intensity of the first interfered optical beam is increased by the interference, and intensity of the second interfered optical beam is decreased by the interference.