Abstract: An RF transmitter comprising an optical source configured to generate a pair of optical lines separated by an RF carrier frequency. The transmitter may comprise a graphene photodetector having at least two electrical contacts; a transmit antenna coupled to a first of the electrical contacts; and an electrical data signal input connected to a second of the electrical contacts. The graphene photodetector is illuminated by the optical source; it may comprise a graphene photo-thermal effect (PTE) photodetector or a bolometric photodetector. A corresponding receiver is also described.

Abstract: An RF transmitter comprising an optical source configured to generate a pair of optical lines separated by an RF carrier frequency. The transmitter may comprise a graphene photodetector having at least two electrical contacts; a transmit antenna coupled to a first of the electrical contacts; and an electrical data signal input connected to a second of the electrical contacts. The graphene photodetector is illuminated by the optical source; it may comprise a graphene photo-thermal effect (PTE) photodetector or a bolometric photodetector. A corresponding receiver is also described.

Abstract: A Wavelength Division Multiplexing (WDM) for an optical fibre comprising a set of optical inputs, one for each wavelength of a WDM optical signal to be transmitted, a graphene electro-absorption modulator (EAM) for each optical input to modulate light from the optical input, and one or more drivers to drive each graphene electro-absorption modulator. The drivers have a data input, a low pass filter to low-pass filter data from the data input to provide low pass filtered data, and an output to drive each graphene electro-absorption modulator with a combination of the low pass filtered data and a bias voltage. The bias voltage is configured to bias the graphene EAM into a region in which, e.g., when the transmission of the graphene electro-absorption modulator increases the effective refractive index for the modulated light decreases and vice-versa to pre-chirp to the modulated light to compensate for dispersion in the fibre.

Abstract: A transmitter (1) is configured to transmit an optical signal, the transmitter comprising an optical dispersion compensator (10) configured to compensate for chromatic dispersion of the optical signal. The optical dispersion compensator comprises a plurality of delay elements (20; 40). The plurality of delay elements (20; 40) have a combined response providing a delay to the transmitted optical signal which varies with frequency.

Abstract: A device (10;150;200) is configured to receive an optical signal. The device comprises a dispersion compensator (210a) comprising a plurality of optical dispersion compensator units (220). Each optical dispersion compensator unit comprises a plurality of delay elements (20;40). The dispersion compensator (210a) is configured to selectively activate one or more of the optical dispersion compensator units (220). The dispersion compensator (210a) is configured to compensate for dispersion of the optical signal with the activated one or more optical dispersion compensator unit (200).

Abstract: A device (10;150;200) is configured to receive an optical signal. The device comprises a dispersion compensator (210a) comprising a plurality of optical dispersion compensator units (220). Each optical dispersion compensator unit comprises a plurality of delay elements (20;40). The dispersion compensator (210a) is configured to selectively activate one or more of the optical dispersion compensator units (220). The dispersion compensator (210a) is configured to compensate for dispersion of the optical signal with the activated one or more optical dispersion compensator unit (200).

Abstract: A method for dual polarisation optical transmission is disclosed. The method comprises splitting a continuous wave light source into first and second sub-channels, optically modulating each sub-channel with a data signal, and superimposing a first pilot tone onto the first optically modulated sub-channel and a second pilot tone, different from the first pilot tone, onto the second optically modulated sub-channel. The method further comprises polarisation multiplexing the first and second sub-channels to form a polarisation multiplexed signal, in which the first and second sub-channels have orthogonal states of polarisation, and transmitting the polarisation multiplexed signal.

Abstract: A transmitter (1) is configured to transmit an optical signal, the transmitter comprising an optical dispersion compensator (10) configured to compensate for chromatic dispersion of the optical signal. The optical dispersion compensator comprises a plurality of delay elements (20; 40). The plurality of delay elements (20; 40) have a combined response providing a delay to the transmitted optical signal which varies with frequency.

Abstract: A method for dual polarisation optical transmission is disclosed. The method comprises splitting a continuous wave light source into first and second sub-channels, optically modulating each sub-channel with a data signal, and superimposing a first pilot tone onto the first optically modulated sub-channel and a second pilot tone, different from the first pilot tone, onto the second optically modulated sub-channel. The method further comprises polarisation multiplexing the first and second sub-channels to form a polarisation multiplexed signal, in which the first and second sub-channels have orthogonal states of polarisation, and transmitting the polarisation multiplexed signal.

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: There is provided an optical switch. The optical switch comprises a first optical waveguide, a second optical waveguide, a first optical ring resonator and a second optical ring resonator. The first optical ring resonator is arranged between the first optical waveguide and the second optical waveguide, wherein the first optical ring resonator is capable of coupling an optical signal travelling along the first optical waveguide in a first direction to the second optical waveguide such that the optical signal travels in a second direction along the second optical waveguide. The second optical ring resonator is arranged between the first optical waveguide and the second optical waveguide; wherein the second optical ring resonator is capable of coupling an optical signal travelling along the first optical waveguide in the first direction to the second optical waveguide such that the optical signal travels in a third direction along the second optical waveguide opposite to the second direction.

Abstract: A device (100) for processing a signal, the device comprising a polarization module (102) configured to receive a multi-wavelength optical input signal (Si) comprising a plurality of wavelengths, and for each wavelength. The polarization module is configured to convert a component of each wavelength having a first polarization mode into a converted component having a second, different, polarization mode. The device further comprises a processing module (104,106,114,128) configured to combine the converted component of each wavelength with a direct component of each wavelength received with said second polarization mode. The processing module is configured to generate a multi-wavelength optical output signal (So) solely having said second polarization mode.

Abstract: A device (100) for processing a signal, the device comprising a polarization module (102) configured to receive a multi-wavelength optical input signal (Si) comprising a plurality of wavelengths, and for each wavelength. The polarization module is configured to convert a component of each wavelength having a first polarization mode into a converted component having a second, different, polarization mode. The device further comprises a processing module (104,106,114,128) configured to combine the converted component of each wavelength with a direct component of each wavelength received with said second polarization mode. The processing module is configured to generate a multi-wavelength optical output signal (So) solely having said second polarization mode.

Abstract: There is provided an optical switch. The optical switch comprises a first optical waveguide, a second optical waveguide, a first optical ring resonator and a second optical ring resonator. The first optical ring resonator is arranged between the first optical waveguide and the second optical waveguide, wherein the first optical ring resonator is capable of coupling an optical signal travelling along the first optical waveguide in a first direction to the second optical waveguide such that the optical signal travels in a second direction along the second optical waveguide. The second optical ring resonator is arranged between the first optical waveguide and the second optical waveguide; wherein the second optical ring resonator is capable of coupling an optical signal travelling along the first optical waveguide in the first direction to the second optical waveguide such that the optical signal travels in a third direction along the second optical waveguide opposite to the second direction.