HIGH-SPEED ANALOG REFRACTIVE-INDEX MODULATOR THAT USES A CHIRAL SMECTIC LIQUID-CRYSTAL

We demonstrate a fast liquid-crystal analog phase modulator composed of a homeotropically aligned electroclinic chiral smectic liquid crystal. Pure phase modulation is obtained by electrical modulation of the refractive index of the liquid crystal. A refractive-index change of 0.045 can be obtained at a 5-mus switching speed with a 15-V/mum applied electric field by use of the commercial electroclinic chiral smectic liquid crystal mixture BDH764E. This results in a pi phase modulation depth at lambda = 0.633 mum in a device of 10-mum thickness.