84 fs PMD detection sensitivity in 2/spl times/40 Gbit/s RZ polarisation multiplex transmission experiment

Interchannel phase modulation of polarisation-multiplexed optical signals results in pulse arrival time variations in the presence of polarisation mode dispersion (PMD). Integration of the voltage controlled oscillator (VCO) input signal in the clock recovery phase locked loop (PLL) allows detection of these. 150 and 84 fs PMD detection sensitivities are demonstrated for 4.8 and 38.4 /spl mu/s measurement intervals, respectively.