Dispersion Limitations in Optical Systems Using Offset DPSK Modulation

Abstract

In M-ary differential phase-shift keying (DPSK), log 2 M information bits are encoded in the phase difference Δo between successive symbols, where Δo assuming values in the set Θ+2(i-1)π/M,i=1,⋯M. When Θ = 0, we have conventional DPSK, while when Θ = 0, we have offset DPSK. Using numerical analysis, we investigate the performance of binary and quaternary offset DPSK for arbitrary Θ in the presence of fiber chromatic dispersion (CD) and first-order polarization-mode dispersion (PMD). We show that the choice of Θ may strongly affect the tolerance of offset DPSK systems to CD and PMD.