Tunable polarization diversity liquid-crystal wavelength filter

A compact polarization-insensitive liquid crystal filter is demonstrated using the polarization diversity technique. The incoming signal is split into two orthogonally polarized beams with a calcite crystal and the beams are filtered using two regions of the liquid crystal Fabry-Perot filter. The optic axes in these two regions are made orthogonal by controlling the surface structure. It is shown that a wide tuning range of 70 nm is possible with a band-pass of about 0.6 nm. Using arbitrarily polarized input light it is demonstrated that polarization-dependent power fluctuations are less than 1 dB.<>