Novel tunable liquid crystal Fabry-Perot filters for Fiber-Optical system

Tunable filters with a wide tunable range that cover the whole C-band , or L-band, or both, have been found wide applications in fiber optical communication system, mainly in three domain: tunable laser, wavelength division multiplexing systems (WDM), and channel monitoring. Due to the growing demand in bit-rate and number of channels in WDM system, tunable narrow band pass filters are required[1]. So far a lot ofefforts have been made to make tunable filters based on Fabry-Perot principle[2,3,4]. The tunable optical filters using a LiNbO3 torsional actuator{2] need a high driving voltage up to 500 volts and has a narrow tunable range. The tunable filter[4] reported by M. lodice is a temperature-tuned silicon etalon filter with a narrow passband however a narrow free spectral range, and tuning speed was not reported. We have successfully combined the liquid crystal technology with the Fabry-Perot to make tunable liquid crystal Fabry-Perot (LCFP) interferometers that have been proven to be competitive in spectroscopy, LIDAR and JR imaging [5,6]. This technology is adaptable to optical networking and telecommunications by the development ofetalons with NIR transmission, and development oftandem and parallel etalon stacks[7]. The advantages ofthe tunable liquid crystal Fabry-Perot filter are: high resolution and wide free spectral range and tunable range, fast response time, solid state (no moving parts), low driving voltage.