Wavelength selection in a Fabry-Perot filter with an axially aligned nematic liquid crystal

A polarization-insensitive, electrically tunable Fabry-Perot filter (FP) with a nematic liquid crystal (NLC) is demonstrated In an axially symmetrical hybrid geometry, the wavelength selection property of the FP filter is independent of the polarization state of the input light in the whole range of tuning. The alignment of a NLC between the two substrates is homeotropic at one surface and axially homogeneous on the other surface. Such alignment preserves in-plane symmetry of the input polarization state for the normal incidence, which makes the resulting transmission through the FP filter be polarization-insensitive.