Interferometric polarization mode dispersion measurements with femtosecond sensitivity

The standard interferometric measurement technique for polarization mode dispersion (PMD) measures the cross correlation of the electromagnetic field at the output of the fiber or optical device under test when a broadband light source is used. The sensitivity (smallest measurable PMD delay) of this technique is limited by the coherence time of the light source. In this contribution, we critically analyze extensions of the interferometric technique to lower values and present a new extension which provides a sensitivity of a few femtoseconds.