A communication device of the disclosure includes a phase synchronizer, a modulator, and a controller. The phase synchronizer generates a second signal on a basis of a first signal received from a communication partner by selectively performing one of a closed loop operation and an open loop operation. The modulator is able to modulate the first signal on a basis of the second signal. The controller controls operations of the phase synchronizer and the modulator.

Aspects are generally directed to free-space transmitters, free-space receivers, and free-space communication methods. In one example, a free-space communication method includes acts of mapping a data payload to one or more symbols based on a symbol set defined by a digital modulation scheme, varying one or more properties of a signal waveform to phase modulate the signal waveform with the data payload, the one or more symbols each having a symbol duration that defines a timing structure of the modulated signal waveform, and fragmenting the timing structure of the modulated signal waveform to conceal one or more waveform properties of the modulated signal waveform.

Techniques for transmitting an optical signal through optical fiber with an improved cost effective stimulated Brillouin scattering (SBS) suppression include externally modulating a light beam emitted from a light source with a high frequency signal. The light beam is also modulated externally with an RF information-carrying signal. The high frequency signals are at least twice a highest frequency of the RF signal. The high frequency signals modulating the light source can be gain and phase adjusted by the first set of gain and phase control circuit to achieve a targeted spectrum shape. The adjusted high frequency signals then are split, providing a portion of the split signals to modulate the light source and another portion of the split signals to the second set of phase and gain control circuit for adjusting a phase/gain. The output of second set of phase and gain control circuits can be applied to the external modulator to eliminate intensity modulation caused by the corresponding high frequency signals that modulate the light source. The spread spectrum for SBS suppression or the optical transmitter's SNR is further improved by cancelling a beat between SBS suppression modulation tones and out of band distortion spectrum of information bearing RF signal.

Techniques and architecture are disclosed for navigating an area with multi-panel luminaires configured to display fiducial patterns. In an embodiment, a system includes a plurality of luminaires located in an area and configured to display one or more fiducial patterns recognizable by a mobile computing device. The luminaire includes a plurality of panels, each panel associated with one or more solid-state light sources. The luminaire also includes at least one driver configured to control the light sources to transmit light through the plurality of panels at varying light intensities to display a fiducial pattern and configured to detect errors in the display of the fiducial pattern.

A method of transmitting communications traffic, the method comprising steps of receiving a sequence of communications traffic bits; and mapping the sequence of communications traffic bits onto a respective one of a plurality of transmission symbols for transmission during a symbol time. Each transmission symbol is identified by a respective first symbol identifier indicative of a respective one or more of a plurality, M, of wavelengths for a transmission signal and a respective second symbol identifier indicative of a respective one or more of a plurality, N, of optical fibers on which to transmit the transmission signal.

A signal processing method is provided. Under the method, a first digital signal can be obtained by an optical transmitter. The first digital signal is a one-dimensional bipolar digital signal. A spectral compression and filtering can be performed by the optical transmitter on the first digital signal to generate a second digital signal. A frequency shift can be performed by the optical transmitter on the second digital signal such that a center location of a spectrum of the frequency-shifted second digital signal is at a frequency of 0.

The present disclosure provides a modulation method, apparatus, and system for imaging scanning signal synchronization. The method includes: transmitting control signals, wherein the control signals include a galvanometer driving signal, a laser scanning signal, and a camera exposure signal, the galvanometer driving signal and the camera exposure signal have a same period, and the laser scanning signal enables laser to be emitted for N times within time for enabling positive oscillation of a galvanometer in one period of the galvanometer driving signal; measuring an actual signal waveform of the galvanometer, and obtaining a noise-reduced waveform by filtering and de-noising the actual signal waveform; performing a waveform comparison detection on the noise-reduced waveform and a corresponding control waveform for the galvanometer driving signal to obtain a waveform deviation; and adjusting the control signals based on the waveform deviation and transmitting the adjusted control signals.

A cryogenic optoelectronic data link, comprising a sending module operating at a cryogenic temperature less than 100 K. An ultrasensitive electro-optic modulator, sensitive to input voltages of less than 10 mV, may include at least one optically active layer of graphene, which may be part of a microscale resonator, which in turn may be integrated with an optical waveguide or an optical fiber. The optoelectronic data link enables optical output of weak electrical signals from superconducting or other cryogenic electronic devices in either digital or analog form. The modulator may be integrated on the same chip as the cryogenic electrical devices. A plurality of cryogenic electrical devices may generate a plurality of electrical signals, each coupled to its own modulator. The plurality of modulators may be resonant at different frequencies, and coupled to a common optical output line to transmit a combined wavelength-division-multiplexed (WDM) optical signal.

A method and apparatus for isolating an RF signal are provided. A first RF signal is received and passed to an input of a 90 degree hybrid. An output of the 90 degree hybrid is connected to a first waveguide and a second output is connected to a second waveguide of an optical modulator. A second RF signal is received and passed to an input of a second 90 degree hybrid. An output of the second 90 degree hybrid is connected to the second waveguide and a second output is connected to the first waveguide of the optical modulator. The optical modulator is biased to produce single side band optical outputs of the RF signals. The single side band optical outputs are passed to an optical notch filter to remove one of the side band outputs. The other of the side band optical outputs is converted to an electrical signal.

The disclosure is directed to a method and system for generating a pilot tone for an optical signal with an optical telecommunications system. The pilot tone is generated in the digital domain by modulating the data to be transmitted to a destination node within the optical telecommunications network. The modulation of the data introduces occurrence modulation to the optical signal.