An optical transmission/reception unit includes a carrier rotatable around an axis of rotation, an optical receiver arranged at the carrier on the axis of rotation so as to receive an optical reception signal from a first direction, an optical transmitter arranged at the carrier adjacent to the optical receiver so as to emit an optical transmission signal in a second direction, and a transmission/reception optic arranged at the carrier on the axis of rotation above the optical receiver, wherein the transmission/reception optic includes a reception optic and a transmission optic arranged in the reception optic, wherein the reception optic is configured to guide the optical reception signal striking the transmission/reception optic towards the optical receiver on the axis of rotation, and wherein the transmission optic is configured to displace onto the axis of rotation the optical transmission signal emitted by the optical transmitter.

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.

Amplitude-modulated (AM) signals spanning a spatial wide area can be efficiently detected using a slowly scanning optical system. The system decouples the AM carrier from the AM signal bandwidth (or carrier uncertainty), enabling Nyquist sampling of only the information-bearing AM signal (or the known frequency bandwidth). The system includes a staring sensor with N pixels (e.g., N>10.sup.6) that searches for a sinusoidal frequency of unknown phase and frequency, perhaps constrained to a particular band by a priori information about the signal. Counters in the sensor pixels mix the detected signals with local oscillators to down-convert the signal of interest, e.g., to a baseband frequency. The counters store the down-converted signal for read out at a rate lower than the Nyquist rate of AM signal. The counts can be shifted among pixels synchronously with the optical line-of-sight for scanning operation.

An optical transmission/reception unit includes a carrier rotatable around an axis of rotation, an optical receiver arranged at the carrier on the axis of rotation so as to receive an optical reception signal from a first direction, an optical transmitter arranged at the carrier adjacent to the optical receiver so as to emit an optical transmission signal in a second direction, and a transmission/reception optic arranged at the carrier on the axis of rotation above the optical receiver and extending across the optical receiver and the optical transmitter, wherein the transmission/reception optic includes a reception optic and a transmission optic arranged in the reception optic, wherein the reception optic is configured to guide the optical reception signal striking the transmission/reception optic towards the optical receiver on the axis of rotation.

A free space optical receiver including a multi-mode transmission medium configured to receive a light beam comprising a plurality of modes, the light beam having been propagated through a free space path. The free space optical receiver also includes a mode separating means configured to separate the plurality of modes for transmission through a corresponding first plurality of transmission media as a corresponding plurality of single-mode light beams, and a combining means configured to combine two or more of the plurality of single-mode beams into a combined beam for transmission through a further transmission medium.

[Problem] To determine a time difference between clocks which, for example, are placed far apart from each other with high accuracy at low cost.

[Solution] In a time comparison system 20, an intermediate station 21 disperses a single optical signal 21c in the spatial region using the optical complex amplitude modulation to simultaneously transmit the optical signal 21c to a plurality of comparative stations 22 and 23 apart from each other. The intermediate station 21 transmits the optical signal 21c while changing the transmission angle using phase modulation, performs intensity scanning for the reflected light c1 of the optical signal 21c, and detects the peak intensity to determine the directions of the comparative stations 22 and 23. The reflected light c1 of the optical signal 21c transmitted to the comparative stations 22 and 23 of which the direction have been determined, is detected to determine a round-trip propagation delay time between the intermediate station 21 and each of the comparative stations 22 and 23. The difference calculation unit 25 calculates a sum of time difference between each of times to and tb associated with the comparative stations 22 and 23 and the time tc associated with the intermediate station 21, and the determined propagation delay time to determine time information of each of the comparative stations 22 and 23. Based on the result of subtracting, from the time information of the comparative stations 22, the time information of the comparative stations 23, the time difference between the comparative stations 22 and 23 is determined.

A device for communication including a gimbal and a communication unit being rotatably supported by the gimbal and having a communication port for optical wireless communication and an imaging unit for capturing an image in a direction in which the communication port executes optical wireless communication is provided. In addition, a communication device including the device for communication and a communication executing unit for executing optical wireless communication using the communication port is provided.

A system and method for performing free space optical communication with a plurality of streetlamp assemblies. The method includes transmitting a light beam from a first free space optical (FSO) unit of a first streetlamp assembly to a second FSO unit of a second streetlamp assembly along a transmission path. A transmission error is detected while transmitting the light beam along the transmission path. A location of one or more smart minors is obtained. An alternate transmission path is determined from the first FSO unit to the second FSO unit or a third FSO unit. The alternate transmission path includes a reflection of the light beam from the one or more smart minors. The first FSO unit is oriented with respect to the alternate transmission path. The light beam is transmitted from the first FSO unit along the alternate transmission path.

An optical transmission/reception unit includes a carrier rotatable around an axis of rotation, an optical receiver arranged at the carrier on the axis of rotation so as to receive an optical reception signal from a first direction, an optical transmitter arranged at the carrier adjacent to the optical receiver so as to emit an optical transmission signal in a second direction, and a transmission/reception optic arranged at the carrier on the axis of rotation above the optical receiver and extending across the optical receiver and the optical transmitter, wherein the transmission/reception optic includes a reception optic and a transmission optic arranged in the reception optic, wherein the reception optic is configured to guide the optical reception signal striking the transmission/reception optic towards the optical receiver on the axis of rotation.

Methods and systems for providing wireless communications for a device. The methods can include receiving an indication from a device that the device is capable of receiving data via optical transmission. The methods can also include utilizing an optical transmitter to transmit one or more packets of data to the device via optical transmission. The methods can also include utilizing an antenna element to transmit one or more packets of data to the device via radio frequency (RF) transmission.