A tunable polarization-independent liquid-crystal Fabry-Perotinterferometer filter

The authors propose a simple structure for a tunable polarization-independent wavelength-selective filter. This successfully fabricated filter consists of a liquid crystal Fabry-Perot interferometer, a γ/4 plate, and a mirror. The input light is divided into a transmitted light and a reflected light. The polarization of this reflected light is rotated 90° by the γ/4 plate and the mirror and then this light is input again into the filter. The bandwidth is 0.48 nm and the tuning range is 50 nm. Fiber-to-fiber loss is approximately 3.9 dB and polarization dependence of the loss is approximately 0.3 dB