Measurement of femtosecond polarization mode dispersion (PMD) using biasedpi-shifted low-coherence interferometry

Conventional coherence interferometry (LCI) can be employed in the measurem ent of polarization mode dispersion (PMD) of fiber-optic components and fib ers. However, the smallest PMD, which can be measured using this technique, is limited by the coherence length of the source. We propose a biased pi-s hifted Michelson interferometer where a birefringent crystal is inserted in front of the interferometer to introduce a bias differential group delay ( DGD) larger than the coherence time of the source. In this way, the limitat ion imposed by the source coherence time has been overcome and PMDs much sm aller than the source coherence time, in the order of several femtoseconds, can be measured. Experimental results for the PMD have been shown and comp ared with Jones matrix eigenanalysis. The theoretical model confirms the ex perimental observations. (C) 2000 Optical Society of America.