Abstract: An analogue to digital converter is arranged to receive and process an analogue optical input signal to produce an N bit digital optical output signal quantised to 2N levels, where N is greater than or equal to 2. The converter has an input for receiving the optical input signal and N processing channels which are each coupled to the input, at least one of said processing channels comprising an optical processing circuit arranged to generate a plurality of digital optical output signals. The optical processing circuit is arranged to change the state of each digital optical output signal corresponding to a respective different value of the analogue optical input signal, and an optical combining circuit for combining the optical output signals in order to generate one bit of the N-bit digital optical signal.

Abstract: An optical signal processor may include an optical waveguide loop, and first and second phase modulator loops. Each of the first and second phase modulator loops may be in optical communication with the optical waveguide loop. The first and second phase modulator loops may include respective control signal input ports to control phase modulation applied by the first and second phase modulation loops. The optical waveguide loop may include two input ports to direct input signals in opposite directions in the optical waveguide loop and may further include an output port to output resulting signals.

Abstract: An analogue to digital converter (100) is arranged to receive and process an analogue optical input signal (110) to produce an N bit digital optical output signal (140) quantised to 2N levels, where N is greater than or equal to 2. The converter (100) has an input (115) for receiving the optical input signal (110) and N processing channels (131, 132, 133) which arc each coupled to the input, at least one of said processing channels comprising an optical processing circuit (201, 202, 203, 204, 205, 206, 207) arranged to generate a plurality of digital optical output signals. The optical processing circuit is arranged to change the state of each digital optical output signal corresponding to a respective different value of the analogue optical input signal, and an optical combining circuit (301, 302, 303, 304) for combining the optical output signals in signal order to generate one bit of the N-bit digital optical signal.

Abstract: An apparatus and method for generating a train of optical pulses. The apparatus comprises an optical resonant cavity (1) for confining an optical signal in the cavity to a number of modes, a modulator (3), and a control signal generator (101). The modulator comprises an interferometer arranged to cause interference of the optical signal with itself to produce an output and controllable material, such as an electro-optic crystal, arranged in a path of the optical signal, an optical property of the controllable material dependent on a control signal (3b) applied to the controllable material such that changes in the optical property alter optical signals travelling that path to affect the interference of the optical signals, and therefore the output of the modulator.

Abstract: Optical signal processor (1) comprising an optical waveguide loop (3), and first and second phase modulator loops (6, 7), each of the first and second phase modulator loops is in optical communication with the optical waveguide loop, and the first and second phase modulator loops each comprises a respective control signal input port (8, 9) to control phase modulation applied by the phase modulation loops, and the optical waveguide loop comprising two input ports (20a, 20b) to direct input signals (10, 11) in opposite senses in the optical waveguide loop and further comprising an output port (20c) to output resulting signals. The first and second phase modulator loops may comprise nonlinear optical loop mirrors. The processor may be an optical logic gate device.