An optical system for seeding an optical transmitter, the system comprising: a first optical transmitter comprising a first reflective optical amplifier ; a second optical transmitter comprising a second reflective optical amplifier , the second optical transmitter being optically coupled to the first optical transmitter ; and an optical cavity for seeding the first reflective optical amplifier with a first optical seed signal, wherein the optical cavity is formed between the first reflective optical amplifier of the first optical transmitter and the second reflective optical amplifier of the second optical transmitter , wherein the first reflective optical amplifier is configured to transmit a first optical signal to the second reflective optical amplifier and the second reflective optical amplifier is configured to provide the first optical seed signal by reflecting a portion of the first optical signal back to the first reflective optical amplifier ; wherein the optical system further comprising a first optical transceiver , the first optical transceiver comprising the first optical transmitter and a first optical receiver , characterised in that the first and second optical transmitters are configured to transmit a respective first and second modulated optical signal, wherein the first optical receiver is configured to receive a first receiver optical signal, the first receiver optical signal comprising the second modulated optical signal from the second optical transmitter and a reflected first modulated optical signal from the first optical transmitter , the first optical transceiver further comprising a first crosstalk cancellation module for removing the reflected first modulated optical signal from the first receiver optical signal. a first optical transmitter comprising a first reflective optical amplifier ; a second optical transmitter comprising a second reflective optical amplifier , the second optical transmitter being optically coupled to the first optical transmitter ; and an optical cavity for seeding the first reflective optical amplifier with a first optical seed signal, wherein the optical cavity is formed between the first reflective optical amplifier of the first optical transmitter and the second reflective optical amplifier of the second optical transmitter , wherein the first reflective optical amplifier is configured to transmit a first optical signal to the second reflective optical amplifier and the second reflective optical amplifier is configured to provide the first optical seed signal by reflecting a portion of the first optical signal back to the first reflective optical amplifier ; wherein the optical system further comprising a first optical transceiver , the first optical transceiver comprising the first optical transmitter and a first optical receiver , characterised in that the first and second optical transmitters are configured to transmit a respective first and second modulated optical signal, wherein the first optical receiver is configured to receive a first receiver optical signal, the first receiver optical signal comprising the second modulated optical signal from the second optical transmitter and a reflected first modulated optical signal from the first optical transmitter , the first optical transceiver further comprising a first crosstalk cancellation module for removing the reflected first modulated optical signal from the first receiver optical signal. <EOS>