An Approach for Calculating the Performance of DPSK Direct Detection Systems with Semiconductor Optical Amplifiers

This paper presents an approach for evaluating the limitation imposed by the amplified spontaneous emission (ASE) noise generated by a semiconductor optical amplifier (SOA) in a direct detection differential phase-shift keying (DPSK) system. This analysis takes into account the effects of an arbitrary receiver baseband filter, whose impulse response is limited to one bit period, as well as the influence of the optical and polarization filters on the non-Gaussian processes generated by this noise. An expression for both the characteristic function of the decision variable and the system error probability in terms of the baseband filter coefficients is deduced.