Fast Electro-Optical Switching and High Contrast Ratio in epoxy-based Polymer Dispersed Liquid Crystals

We report the observation of an electro-optical switching effect from an opaque to a transparent state occurring at a threshold value of the applied field in a Polymer Dispersed Liquid Crystal (PDLC). Optical responses of the composite film under the conditions of an externally applied ac electric field (2-5 Vp-p /ƒÝ) and a film thickness (50ƒÝm), were determined using an Argon laser (wavelength 514 nm). The experimental results showed promising switching times with a rise time of 190 ƒÝsec and a decay time of 2 msec and an exceptionally high contrast ratio up to 410. These results demonstrate the validity of employing this new PDLC in electro-optical devices.