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.

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.

A technology is described for optical communication. An example of the technology can include receiving an event stream containing indications of independent events detected by pixels in an event camera. An event may be a change in brightness detected by a pixel in the pixel array, and the pixel independently generates an indication of the event in response to detecting the event. The event stream can be demultiplexed into a plurality of communication streams containing related events associated with a plurality of communication sources. The events contained in a communication stream can be aggregated based in part on an event proximity and an event time that associates an event with other events contained in the event stream. The plurality of communication streams can be demodulated to extract optically transmitted information from the plurality of communication streams, which can be sent to a data consumer.

Atmospheric turbulence degrades decoding and data recovery from optically transmitted signals. For example, atmospheric turbulence can induce power coupling from the transmitted Gaussian mode to higher-order modes, resulting in significantly degraded mixing efficiency and system performance. Systems and methods are provided to generate a signal that is a conjugate of the atmospheric noise which is combined with a received data signal to ameliorate atmospheric noise. An optical pilot beam may be transmitted with an optical data beam and received by a receiver which utilizes the optical pilot beam to generate the signal that is a conjugate of the atmospheric noise.

Free-Space quantum keyless private communication method according to a communication protocol comprising exchanging information between an emitter (100) and a receiver (200) through a main quantum-classical channel and with an eavesdropper tapping said main channel through a wiretap channel, based on the wiretap channel model, wherein the overall degradation of the wiretap channel is superior than that of the main channel, comprising the steps of preparing, at the emitter (100), a message M composed of classical bits, coding said message M so as to transform it into a coded message X, practical modulating the amplitude and/or the phase of the optical pulses of the coded classical bits, sending the encoded message to the receiver (200) through a classical-quantum channel (500), such that an eavesdropper (300) tapping said channel is provided with partial information about the said states only, detecting and decoding the received message through quantum security analysis.

In order to efficiently receive spatial light without using a condensing lens, this light receiving device comprises: a first light guide body that has at least a first light receiving surface and a first light emission end and guides, in an oriented manner, signal light entering from the first light receiving surface to the first light emission end; a second light guide body that has at least a second light receiving surface and a second light emission end, the second light receiving surface being connected to the first light emission end, and that guides, in an oriented manner, signal light entering from the second light receiving surface to the second light emission end; and a light receiver that has a light receiving part connected to the second light emission end and that converts the signal light received by the light receiving part to an electrical signal.

A method of key distribution, a key distribution system, a single photon source system and a method of generating single photons. The method of key distribution comprises the steps of: providing a free space optics, FSO, link between a transmitter and a receiver; detecting whether an eavesdropper is present along the FSO link; transmitting individual photons or weak coherent pulses, as an approximation of individual photons, each encoding a basic unit of the key according to a binary or higher number base system from the transmitter to the receiver; and comparing timing information associated with the transmission and reception of the individual photons for determining the key when it is detected that no eavesdropper is present along the FSO link.

An optical receiver including an optical resonator and a steering mechanism coupled to the at least one optical resonator is disclosed. The optical resonator is configured to receive a phase modulated input optical signal and to produce an intensity modulated output optical signal. An intensity modulation of the output optical signal is representative of the phase modulation of the input optical signal. The optical receiver further comprises an optical-electrical converter that detects the intensity modulated output optical signal and converts the intensity modulated output optical signal to an electrical signal, and signal processor that receives the electrical signal, performs symmetric phase change measurements based on the electrical signal, and provides a control signal to actuate the steering mechanism to steer the optical resonator to maintain normal incidence of the phase modulated input optical signal on a surface of at least one optical resonator.

An optical receiver for use in free space communication from a transmitter to the optical receiver is configured for receiving optical signals from the transmitter. The optical receiver includes optics for collecting the optical signals, a demodulator for converting the optical signals so collected into a data stream, a signal processing unit for processing the data stream into an analog signal, and an analog-to-digital converter for converting the analog signal into a digital output. The demodulator includes a plurality of apertures and at least one Fabry-Perot etalon, through which at least a portion of the optical signals is transmitted. The demodulator also includes at least one phase detection region for detecting at least the portion of the optical signals transmitted through the at least one Fabry-Perot etalon to form a phase signal.

A laser receiver device and an associated input coupler are provided. In this regard, a chip-scale laser receiver device is provided that includes an input coupler that is configured to receive a gaussian beam. The input coupler includes a first waveguide having an optically-transparent material and a second waveguide coupled to the first waveguide. The second waveguide has a tapered configuration that tapers to a predetermined width across a length of not less than 500 micrometers. The input coupler further includes a third waveguide coupled to the second waveguide. The third waveguide has a tapered configuration that tapers to a predetermined width across a length of not less than 250 micrometers. The chip-scale laser receiver device further includes a bus optical waveguide coupled to receive a signal output from the input coupler, and to output a wavelength-multiplexed laser signal.