Abstract: An optical transmitter, comprising: a master laser device for generating a master signal; one or more slave laser devices, injected with the master signal such that signals generated by the one or more slave laser devices are phase-locked with the master signal; an input for receiving one or more data streams to be transmitted, the one or more data streams being used to modulate respectively the one or more slave laser devices, such that each signal generated by the one or more slave laser devices respectively comprises a modulated part and a carrier part; and an interfering arrangement, for destructively interfering the signals generated by the one or more slave laser devices with a signal derived from the master signal, so as to generate an output signal in which the carrier part is at least partially cancelled. In embodiments, the transmitter comprises multiple slave laser devices, whose outputs can be coherently multiplexed together to generate multiple-bit output signals.

Abstract: An optical transmitter, comprising: a master laser device for generating a master signal; one or more slave laser devices, injected with the master signal such that signals generated by the one or more slave laser devices are phase-locked with the master signal; an input for receiving one or more data streams to be transmitted, the one or more data streams being used to modulate respectively the one or more slave laser devices, such that each signal generated by the one or more slave laser devices respectively comprises a modulated part and a carrier part; and an interfering arrangement, for destructively interfering the signals generated by the one or more slave laser devices with a signal derived from the master signal, so as to generate an output signal in which the carrier part is at least partially cancelled. In embodiments, the transmitter comprises multiple slave laser devices, whose outputs can be coherently multiplexed together to generate multiple-bit output signals.

Abstract: An optical regenerator for regenerating a multi-level phase encoded signal. A first non-linear medium (HNLF1) generates a comb of frequency harmonics from the signal under the action of a coherent pump, each component bearing the phase encoded data. A filter selects the first and (M?1)th order components. The filtered signal is then input to a second non-linear medium (HNLF2) where a further pump is applied, to coherently add the first and (M?1)th order components and regenerate the signal by reducing phase noise.

Abstract: An optical device, suitable for use either as a coherent receiver or analog-to-digital converter, of optical phase modulated signals borne on a carrier. The signal is four-wave mixed with a pump to generate a non-linear comb of a series of harmonic components of the signal. The modulation-free carrier is also combined with the pump to generate an equivalent linear comb matched in frequency to the components of the non-linear comb. The harmonic and modulation-free components are linearly combined so they interfere in a pairwise manner, and then the interfered frequency components are separated out in an optical wavelength division demultiplexer into a plurality of frequency-specific optical output channels. A plurality of photodetectors connected to respective ones of the optical output channels then converts the analog values in each channel to respective electronic signals which are then digitized using a processor into binary digits using a thresholding process.

Abstract: An optical regenerator for regenerating a multi-level phase encoded signal. A first non-linear medium (HNLF1) generates a comb of frequency harmonics from the signal under the action of a coherent pump, each component bearing the phase encoded data. A filter selects the first and (M?1)th order components. The filtered signal is then input to a second non-linear medium (HNLF2) where a further pump is applied, to coherently add the first and (M?1)th order components and regenerate the signal by reducing phase noise.