A novel optical homodyne differential phase shift keying receiver

In this paper we describe a new optical homodyne DPSK receiver system. In a conventional DPSK structure we add an optical amplifier in the delayed branch. The amplifier noise is partially cancelled through a balanced circuit before photodetection. Performance is presented for a range of amplifier parameters. Results are presented for cases with and without laser phase noise. We display results in terms of the number of photons per bit needed to obtain an average error probability of 10-9as a function of optical amplifier gain for different values of optical amplifier spontaneous emission factor. We also plot average error probability as a function of received optical energy for different values of bit rate-to-linewidth ratio. For a certain range of relevant parameters, this receiver can perform well close to a homodyne PSK receiver.