Impact of Optical Filtering on DPSK Reception

We discuss the influence of optical and electrical filtering on the performance of beat-noise limited direct detection of differential phase shift keying (DPSK). Our simulations, supported by 40-Gbit/s measurements, show that balanced DPSK detection outperforms both its single-ended equivalent and on/off keying (OOK) by ~2.7 dB, with higher gains at narrower optical filter bandwidths.