Abstract: An opto-electronic oscillator (10) comprising: an optical source (12) to generate an optical carrier signal having a carrier wavelength; an optical phase modulator (14) to apply a sinusoidal phase modulation to the optical carrier signal to generate two first order sidebands having a ? phase difference between them; an optical phase shifter (16) comprising an optical resonator configured to apply a substantially ? phase-shift to one of the first order sidebands at a preselected wavelength within an optical spectrum of said first order sideband; and a photodetector (18) configured to perform optical heterodyne detection of the optical carrier signal with both: said one of the first order sidebands substantially it phase shifted by the optical resonator; and the other of the first order sidebands, to generate an electrical carrier signal (20), and wherein a first part of the electrical carrier signal (20a) is delivered to an electrical output (22) and a second part of the electrical carrier signal (20b) is deli

Abstract: An opto-electronic oscillator (10) comprising: an optical source (12) to generate an optical carrier signal having a carrier wavelength; an optical phase modulator (14) to apply a sinusoidal phase modulation to the optical carrier signal to generate two first order sidebands having a ? phase difference between them; an optical phase shifter (16) comprising an optical resonator configured to apply a substantially ? phase-shift to one of the first order sidebands at a preselected wavelength within an optical spectrum of said first order sideband; and a photodetector (18) configured to perform optical heterodyne detection of the optical carrier signal with both: said one of the first order sidebands substantially it phase shifted by the optical resonator; and the other of the first order sidebands, to generate an electrical carrier signal (20), and wherein a first part of the electrical carrier signal (20a) is delivered to an electrical output (22) and a second part of the electrical carrier signal (20b) is deli

Abstract: An optical carrier selector system is provided for selecting a wanted carrier signal from a multi-carrier signal comprising a plurality of carrier signals. The optical carrier selector system comprises a series of optical filter devices. Each optical filter device of the series comprises an input port for receiving a signal comprising two or more carrier signals, each optical filter device being configured to filter out an unwanted carrier signal. Each optical filter device also comprises an output port for outputting at least the wanted carrier signal and any remaining signals that have not been filtered out by that particular optical filter device, and a drop port for outputting the unwanted carrier signal that is being filtered out by the respective optical filter device.

Abstract: An optical carrier selector system is provided for selecting a wanted carrier signal from a multi-carrier signal comprising a plurality of carrier signals. The optical carrier selector system comprises a series of optical filter devices. Each optical filter device of the series comprises an input port for receiving a signal comprising two or more carrier signals, each optical filter device being configured to filter out an unwanted carrier signal. Each optical filter device also comprises an output port for outputting at least the wanted carrier signal and any remaining signals that have not been filtered out by that particular optical filter device, and a drop port for outputting the unwanted carrier signal that is being filtered out by the respective optical filter device.

Abstract: The present invention relates to Digital-to-Analog conversion in the optical or photonic domain. The present invention provides a digital-to-analog converter (DAC) (100) arranged to receive an N-bit digital optical signal (105) and to process the N-bit digital optical signal to generate an analog optical signal (110). The DAC comprises a photonic circuit (120a, 120b) arranged to adjust the amplitude of each bit of the N-bit digital optical signal dependent on the amplitudes of at least one of the other bits of the N-bit digital optical signal. The amplitudes are adjusted using a non-linear optical effect in order to generate respective outputs for each bit. The DAC also comprises a photonic combiner (145) arranged to combine the outputs for each bit to generate the analog output signal (110).

Abstract: The present invention relates to Digital-to-Analog conversion in the optical or photonic domain. The present invention provides a digital-to-analog converter (DAC) (100) arranged to receive an N-bit digital optical signal (105) and to process the N-bit digital optical signal to generate an analog optical signal (110). The DAC comprises a photonic circuit (120a, 120b) arranged to adjust the amplitude of each bit of the N-bit digital optical signal dependent on the amplitudes of at least one of the other bits of the N-bit digital optical signal. The amplitudes are adjusted using a non-linear optical effect in order to generate respective outputs for each bit. The DAC also comprises a photonic combiner (145) arranged to combine the outputs for each bit to generate the analog output signal (110).

Abstract: An optical logic device has a first mirror confronting a second mirror, and a saturable absorber located between the mirrors. Radiation that is output from the device is output via the first mirror. The reflectivity of the first mirror is such that, in use, for incident radiation which has an intensity that is above a given value, the intensity of exiting radiation is below a threshold. For incident radiation that is below the given value, the intensity of exiting radiation is above the threshold.

Abstract: A method of extracting a predetermined channel from an OTDM signal includes the steps of combining at the inlet of an SOA the OTDM signal and an impulsive signal with impulses temporally synchronized with the channel to be extracted to produce in the SOA FWM, XGM and XPM effects which shift to a length c the channel chosen for extraction with c outside the length d of the OTDM signal with the other channels outlet from the SOA and filtering the SOA outlet to extract components with c d that represent respectively the desired channel and the cleaned OTDM signal. A multiplexer in accordance with the method includes an inlet (14) of an OTDM signal sent to an SOA (24) together with an appropriate impulsive signal. The SOA outlet is filtered by filters (28, 29) to obtain the signal of the extracted channel (16) and the cleaned OTDM signal (15).

Abstract: A method of extracting a predetermined channel from an OTDM signal includes the steps of combining at the inlet of an SOA the OTDM signal and an impulsive signal with impulses temporally synchronized with the channel to be extracted to produce in the SOA FWM, XGM and XPM effects which shift to a length c the channel chosen for extraction with c outside the length d of the OTDM signal with the other channels outlet from the SOA and filtering the SOA outlet to extract components with c d that represent respectively the desired channel and the cleaned OTDM signal. A multiplexer in accordance with the method includes an inlet (14) of an OTDM signal sent to an SOA (24) together with an appropriate impulsive signal. The SOA outlet is filtered by filters (28, 29) to obtain the signal of the extracted channel (16) and the cleaned OTDM signal (15).

Abstract: An optical logic device comprising a first mirror confronting a second mirror, a saturable absorber located between the mirrors and radiation which is output from the device is output via the first mirror, and the reflectivity of the first mirror being such that, in use, for incident radiation which has an intensity that is above a given value, the intensity of exiting radiation is below a threshold, and for incident radiation that is below the given value, the intensity of exiting radiation is above the threshold.