Improvements in secure communication using drones. The communication uses aircraft to provide a secure communication link that prevents undesirable reception. The secure link can be between two people, groups or more specific people. Optical transmission can be from laser, infrared, ultraviolet, white light or a particular wavelength of light. One or multiple of aircraft to relay information between senders and receivers. The aircraft can be drones that operate within buildings or with overhead aircraft. The aircraft can intelligently follow or lead a person to maintain a line-of-sight. Each user can have their own tracking aircraft and the aircraft can communicate between each other using light and/or wireless communication to optimize line-of-sight between the aircraft over geographic medium. The geographic medium may include one or more of terrain, air, water, and space. The object may be a soldier, vehicle, drone, or ballistic.

A radio communication system comprising an optical carrier generator for generating at least a pair of frequency spaced optical carrier signals, a transceiver configured to modulate a first portion of the pair of spaced optical carrier signals with downlink (DL) information to generate a modulated first optical signal, combine an unmodulated second optical signal formed of a remaining unmodulated second portion of the pair of spaced optical carrier signals with the modulated first optical signal to form a combined optical signal for transmission over an optical link, receive an optical uplink (UL) signal from said optical link, said optical UL signal comprising UL information modulated on said unmodulated second portion of the spaced optical carrier signals and down convert said received optical UL signal using a photodetector to output an electrical signal at a baseband frequency.

A radio communication system comprising an optical carrier generator for generating at least a pair of frequency spaced optical carrier signals, a transceiver configured to modulate a first portion of the pair of spaced optical carrier signals with downlink (DL) information to generate a modulated first optical signal, combine an unmodulated second optical signal formed of a remaining unmodulated second portion of the pair of spaced optical carrier signals with the modulated first optical signal to form a combined optical signal for transmission over an optical link, receive an optical uplink (UL) signal from said optical link, said optical UL signal comprising UL information modulated on said unmodulated second portion of the spaced optical carrier signals and down convert said received optical UL signal using a photodetector to output an electrical signal at a baseband frequency.

A transceiver module for providing operational resilience is presented. The transceiver module is configured to receive first data via a first optical module in a first configuration of operation and detect, using an adapter that is operationally connected to the first optical module, an operational failure of the first optical module. In response to detecting the operational failure, the transceiver module is configured to switch, via the adapter, from the first configuration of operation to a second configuration of operation by: automatically engaging a second optical module; triggering the first data that was initially directed into a first input port of the first optical module to be directed into a second input port of the second optical module; and receiving the first data from a second output port of the second optical module.

A communication device includes an interleaving unit that determines an interleaving length of transmit data to be transmitted through free-space optical communication, and interleaves the transmit data based on the determined interleaving length, and a shaping unit that shapes the interleaved transmit data so as to make the interleaving length detectable on a receiving side of the free-space optical communication.

An optical interconnect computing module having free space optical interconnects that form communication links with other systems with like optical interconnects and with computer blades contained within the computing module. The computing module adapts to changes in the position and orientation and other factors of the optical interconnects. The optical interconnects utilize solid-state electronic and optoelectronic components and optical components. The ability to adapt is controlled by an algorithm implemented in software, firmware and logic circuits. Computing modules within an equipment rack and between equipment racks as well as blades contained within a computing module may experience changes in position and orientation due to installation misalignment, servicing of equipment, vibrations, floor sagging, thermal expansion and contraction, earthquakes, line-of-sight obstructions, manufacturing imperfections and other sources.

Methods, devices, and systems are described for free space optical communication. An example device can comprise a defocuser configured to receive an optical signal from a laser and control a beam divergence of the optical signal. The optical signal can comprise a data signal and a beacon signal. The device can comprise a controller configured to cause the defocuser to adjust the beam divergence based on an operational mode of the laser.

A communication device includes an interleaving unit that determines an interleaving length of transmit data to be transmitted through free-space optical communication, and interleaves the transmit data based on the determined interleaving length, and a shaping unit that shapes the interleaved transmit data so as to make the interleaving length detectable on a receiving side of the free-space optical communication.

There includes: an optical splitter splitting modulated light into local oscillator light and signal light beams; a phase adjustment unit adjusting phases of signal light beams; an optical amplification unit amplifying signal light beams phase-adjusted; an optical phased array antenna outputting signal light beams amplified to space; a phase control unit synchronizing with a reference signal light beams, output from the optical phased array antenna and multiplexed with the local oscillator light; an acquisition and tracking mechanism adjusting output angles of signal light beams; an angle detection unit detecting arrival angles of received light; and a control unit setting the reference signal to first reference signals having different frequencies, supplementing the received light based on a detection result, setting the reference signal to second reference signals having equal frequencies, and tracking the received light based on the detection result.

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. Photodetectors at the single-mode outputs convert the received light into electrical signals that are demodulated for communications and whose amplitudes are used to derive the tilt information.