Patent ID: 6271899
Filing Date: 2001-08-07
Classification: G02F

Abstract:
A tuneable filter having a transmission-wavelength characteristic with at least one maximum or minimum comprising:at least one resonant cavity;a plurality of layers of nano phase polymer dispersed liquid crystal (PDLC) material contained within and forming part of said resonant cavity, wherein the PDLC material is polarisable by means of an applied electric field,at least one layer of dielectric material on each side of the PDLC material, said dielectric material having a refractive index different from that of the PDLC material, andmeans for applying a variable electric field across the PDLC material,wherein variation of the electric field applied across the PDLC material gives rise to variation of the wavelengths at which the maximum or minimum occurs in the transmission-wavelength characteristic, wherein the filter comprises alternate layers of a transparent dielectric material and the PDLC material substantially parallel to each other.