SMECTIC LIQUID-CRYSTAL TUNABLE FILTERS

Tunable filters, capable of spectral discrimination, have applications in optical sensing and signal processing, wavelength division multiplexing and demultiplexing, colorimetry and color displays. In this paper we present results on the design and fabrication of a new class of tunable filters, which employ smectic A' electroclinic and smectic C” ferroelectric liquid crystals (PLC's). The first FLC tunable filter demonstrated used binary smectic c material in a Lyot filter geometry to switch discretely between two wavelengths at 440 nm and 660 nm, with 50 nm resolution. A second filter has been designed and demonstrated using smectic A' electroclinic materials to continuously tune over one hundred nanometers in the visible. Computer simulations and experimental results on these filter designs will be presented. © 1991 Gordon and Breach Science Publishers S.A.