Analysing the penalty induced by PDλ of MZI in DQPSK receiver using novel measuring technique

The first demonstration is described of the quality degradation in a differential quadrature phase shift keying (DQPSK) receiver due to the polarisation dependent wavelength response (PD lambda) of a Mach-Zehnder interferometer (MZI) and carrier frequency drifting. In the method, the value of PD lambda and the corresponding penalty can be measured simultaneously at the receiver. Experimental data shows good agreement with the analysis.