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 single photons communication method and system is provided. In an example, an information loading module in a transmitting terminal of the single photons communication system may code to-be-sent target information as a corresponding target modulation frequency according to a pre-saved relationship between information and modulation frequency, and perform frequency modulation on a quantum state of communication light generated by a light source by using the target modulation frequency so that the transmitting terminal may send out modulated target communication light. After receiving the target communication light, an information decoding module in a receiving terminal of the single photons communication system may decode the target modulation frequency from a sequence of receiving photons of the target communication light through Fourier transform or other ways, and obtain target information corresponding to the target modulation frequency according to the relationship between information and modulation frequency.

Techniques are disclosed for emitting position information from luminaires. Luminaire position information may be emitted via a light-based communication (LCom) signal that comprises data including the position information. The data may include relative and/or absolute position information for the luminaire and may indicate the physical location of the luminaire. Relative position information for the luminaire may include coordinates relative to a point of origin within the environment. Absolute position information for the luminaire may include global coordinates for the luminaire. In some cases, the absolute position information for a luminaire may be calculated using position information for the luminaire relative to a point of origin and the absolute position of the point of origin. The data may also include an environment identifier, which may indicate a map to use for the interpretation of position information for the luminaire. The techniques can be used for both stationary and mobile luminaires.

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 fibres on which to transmit the transmission signal.

A signalling apparatus comprising: a non-light-emitting element arranged to transmit and/or reflect light from a light-emitting element, the non-light-emitting element having a variable transmission and/or reflectance respectively, and the non-light-emitting element being separate from the light-emitting element; and a controller configured to control the transmission and/or reflectance of the non-light-emitting element in order to temporally modulate the light and to thereby embed data into the light in a manner imperceptible to human vision; wherein the non-light-emitting element is arranged to transmit and/or reflect the light towards a detecting apparatus housed in a unit separate from the light-emitting element and non-light-emitting element, in order for the embedded data to be detected by the detecting apparatus.

An optical communication system includes a data transmitter. The data transmitter includes at least one optical emission device to output light energy as an optical beam having an operating bandwidth; a beam dividing device arranged to divide the operating bandwidth of the optical beam into bandwidth portions of plural communication bands; an array of graphene switches to: spectrally segregate a bandwidth portion of at least one communication band into plural channels by adjusting at least one graphene switch, and modulate the bandwidth portion to selectively produce an optical output signal with wavelengths that correspond to one or more of the channels, wherein a presence and absence of energy within channels of the communication band will constitute an information packet for data communication. The system includes a focusing grating to receive and focus a first set of wavelengths of the optical output signal reflected by the array of graphene switches.

The invention provides a communication system (500), a lighting system, a method of transmitting information and a computer program product. The communication system according to the invention is configured for transmitting data via visible light. The communication system comprises a signal generator (530) for generating a light driving signal (200) being a frequency shift key modulated signal comprising a sequence of signal parts (215, 225), each signal part being modulated at a first or second frequency in accordance with the data, the signal parts modulated at the first frequency having first pulses in first periods (T0) and the signal parts modulated at the second frequency having second pulses in second periods (T1). Energy of the visible light corresponding to a pulse in a respective period has center of gravity in time. The pulses in the periods are positioned so that the center of gravity is at the center of the period for reducing human-perceivable frequency components in the visible light driving 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.

An optical transmitter transmits an orthogonal frequency division multiplexing symbol in which only one-half of available subcarriers are modulated with data and the remaining subcarriers are suppressed by not modulating with data. The transmission is of duration equal to half the symbol period of the OFDM symbol, resulting in a half-cycle transmission. An optical receiver receives the half-cycle transmission OFDM symbol, regenerates the full time domain representation and recovers data modulated on the one-half of available subcarriers. The modulated subcarriers and the suppressed subcarriers alternate in the frequency domain.

The present invention relates to an image sensor communication (ISC) system and method for enabling communication between an LED and a rolling shutter camera using a rolling shutter modulation method. The image sensor communication system according to an embodiment of the present invention comprises: a coding unit for coding transmission data to be transmitted; an LED which is turned on/off according to the transmission data coded in the coding unit; a rolling shutter camera for continuously photographing, at each of a plurality of rows in a rolling shutter manner, on/off images according to the on/off of the LED; an image processing unit for generating brightness signals according to brightness values of the on/off images of the LED photographed at each of the plurality of rows by the rolling shutter camera; and a data extraction unit for extracting the transmission data from the brightness signals of the on/off images of the LED generated by the image processing unit.