A coherent optical receiver for AM optical signals has a photonic integrated circuit (PIC) as an optical front-end. The PIC includes a polarization beam splitter followed by two optical hybrids each followed by an opto-electric (OE) converter. Each OE converter includes one or more differential detectors and one or more squaring circuits, which outputs may be summed. The PIC may further include integrated polarization controllers, wavelength demultiplexers, and/or tunable dispersion compensators.

Systems and methods for encoding a data signal as a pulse position modulation (PPM) signal and decoding a PPM signal to output the original data signal. The method of encoding may comprise receiving an input data signal; converting the data within the input data signal to a sequence of PPM symbol values; and generating a PPM signal comprising an alternating sequence of synchronisation pulses and data pulses. The PPM signal may be generated by generating a plurality of synchronisation pulses at a fixed pulse repetition rate; and generating a sequence of data pulses with each data pulse having a time delay from a preceding synchronisation pulse, whereby the sequence of data pulses represent the sequence of PPM symbol values.

A system for Nyquist zone disambiguation of a received broadband RF signal is disclosed. The system includes continuous-wave (CW) and pulsed photonic sources whose outputs may be combined into a single input. Both CW and pulsed components of the combined photonic input are modulated by sampling the received RF input signal. The system includes hybrid couplers for IQ demodulation of the modulated combined photonic signal. The system demultiplexes the demodulated inphase and quadrature differential photonic signals into their CW and pulsed component signals. The pulsed component signals may be digitized by narrowband multibit analog-digital converters (ADC) while the CW component signals are digitized by high speed low latency mono-bit ADCs to determine frequency components (e.g., bandwidth information) and other spectrum information of the RF input signal.

Provided is an in-store dual-mode communication system in which shelves are disposed within a commercial space. A server is coupled to the Internet and/or a wide-area network and is configured to send and receive communications. Also provided are light-based messaging units that are located on and/or attached to such shelves, each: 1) having a light source, 2) receiving a communication from the server, and 3) in response to receipt of such communication, turning the light source on and off so as to broadcast a digital message that was included within such communication, as a binary-encoded digital signal corresponding to on/off states of the light source. A user device: (i) receives, via its light sensor, and then decodes the binary-encoded digital signal from a light-based messaging unit in order to obtain the digital message that corresponds to it; and also (ii) communicates with the server via its wireless interface.

An optical transceiver according to an exemplary aspect of the invention includes an interferometer including an input-side optical coupler, an output-side optical coupler, and two arms through which to propagate light and disposed between the input-side optical coupler and the output-side optical coupler, adding a bias phase difference of approximately /2+2n, n representing an integer, between light beams propagating through the two arms; an optical phase modulator generating an optical signal obtained by modulating a phase of continuous wave light to be inputted depending on an electrical signal to be inputted; and an optical delay device making a difference in time for which the optical signal modulated by the optical phase modulator reaching the output-side optical coupler, wherein the optical phase modulator operates by changing carrier density in a silicon optical waveguide.

An optical wireless communication apparatus includes: a modulator for generating a reference signal including periodically repeating binary zeros and ones, receiving an input of a first binary data signal, and outputting a second binary data signal, wherein the second binary data signal has the same frequency as the reference signal, and has the same phase as the reference signal when the first binary data signal comprises binary zeros and has an opposite phase to the reference signal when the first binary data signal comprises binary ones, or has the same phase as the reference signal when the first binary data signal comprises binary ones and has an opposite phase to the reference signal when the first binary data signal comprises binary zeros, and a transmitter for turning a first light source on or off according to the reference signal, and turning a second light source on or off according to the second binary data signal.

An optical wireless transmission device according to an embodiment of the present invention comprises: a modulation unit for receiving input of a first input signal and outputting a first output signal; and a light source control unit for controlling a first light source in accordance with the first output signal. The first output signal repeats 0 and 1 in a first phase during clock time if a binary value of the first input signal is 0, and repeats 0 and 1 in a phase opposite from the first phase during the clock time if a binary value of the first input signal is 1.

An apparatus includes an optical data receiver to receive a phase-modulated optical signal and to demodulate data therefrom. The optical data receiver includes an optical power splitter, first and second optical intensity detectors, and a digital signal processor. The digital signal processor is connected to receive digital values of intensity measurements of each of the optical intensity detectors. The first optical intensity detector is connected to receive light from the optical power splitter via a first optical path, and the second optical intensity detector is connected to receive light from the optical power splitter via a second optical path. The first and second optical paths have channel functions with different frequency dependencies.

Optical receivers and methods for balanced signal detection using an optical resonator. In one example, an optical receiver includes an optical resonator that receives an optical signal, accumulates resonant optical signal energy, and emits first output optical signal energy from a first output and second output optical signal energy from the second output. In response to a modulation of the optical signal, the optical resonator is configured to disrupt the first and second output optical signal energies to convert the modulation of the optical signal into an intensity modulation of the first and second output optical signal energies. The optical receiver includes a first detector that receives the first output optical signal energy and detects the intensity modulation of the first output optical signal energy, and a second detector that receives the second output optical signal energy and detects the intensity modulation of the second output optical signal energy.

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, each one of the plurality of apertures being optically connected with an etalon of an optical path length that is different from the optical path length of another etalon optically connected with another one of the plurality of apertures.