A device configured to receive an optical signal, the device comprising: a plurality of chromatic dispersion compensators (210a, 210b), each comprising a plurality of optical dispersion compensator units, wherein each optical dispersion compensator unit comprises a plurality of delay elements (20;40), wherein each of the chromatic dispersion compensator (210a, 210b) is configured to selectively activate one or more of the optical dispersion compensator units, wherein each of the chromatic dispersion compensator (210a, 210b) is configured to compensate for dispersion of the optical signal with the activated one or more optical dispersion compensator unit, wherein each of said delay element (20;40) is configured to apply a delay to a sub-band of the optical signal, and wherein the sub-bands of the plurality of delay elements (20;40) overlap in frequency such that a combined time delay from the plurality of delay elements of each optical dispersion compensator unit is arranged to be a predefined function which compensates for chromatic dispersion of a transmission medium; wherein each optical dispersion compensator unit is configured to apply a delay to the optical signal which varies substantially linearly with frequency over a channel bandwidth; wherein the device further comprises a polarization controller configured to receive the optical signal which comprises one or more wavelength having a combination of a first polarization mode, TM, and a different, second, polarization mode, TE, the polarization controller configured to convert the received combination of polarizations into a plurality of optical signals, each having only one polarization to be input into one of the chromatic dispersion compensators (210a, 210b) respectively wherein the polarization controller and chromatic dispersion compensators (210a, 210b) are implemented as an integrated photonics circuit. a plurality of chromatic dispersion compensators (210a, 210b), each comprising a plurality of optical dispersion compensator units, wherein each optical dispersion compensator unit comprises a plurality of delay elements (20;40), wherein each of the chromatic dispersion compensator (210a, 210b) is configured to selectively activate one or more of the optical dispersion compensator units, wherein each of the chromatic dispersion compensator (210a, 210b) is configured to compensate for dispersion of the optical signal with the activated one or more optical dispersion compensator unit, wherein each of said delay element (20;40) is configured to apply a delay to a sub-band of the optical signal, and wherein the sub-bands of the plurality of delay elements (20;40) overlap in frequency such that a combined time delay from the plurality of delay elements of each optical dispersion compensator unit is arranged to be a predefined function which compensates for chromatic dispersion of a transmission medium; wherein each optical dispersion compensator unit is configured to apply a delay to the optical signal which varies substantially linearly with frequency over a channel bandwidth; wherein the device further comprises a polarization controller configured to receive the optical signal which comprises one or more wavelength having a combination of a first polarization mode, TM, and a different, second, polarization mode, TE, the polarization controller configured to convert the received combination of polarizations into a plurality of optical signals, each having only one polarization to be input into one of the chromatic dispersion compensators (210a, 210b) respectively wherein the polarization controller and chromatic dispersion compensators (210a, 210b) are implemented as an integrated photonics circuit.