Experimental Measurement of Optical Phase Variance in RZ-DPSK Systems Using Direct Detection After Demodulation by an MZDI

Phase jitter is the major impairment of long-haul phase-shift keying systems. In this letter, we propose and investigate a novel experimental method to estimate the optical phase variance of return-to-zero differential phase-shift-keyed (RZ-DPSK) systems. The means and variances of the power detected before and after DPSK demodulation are the only physical parameters needed to determine the optical phase variance. This can be easily measured with the histogram function of a fast oscilloscope. Numerical simulations confirm a posteriori the accuracy of the method which can be considered as a useful and simple tool to characterize a DPSK transmission