We report lasing from a simple wafer structure made of a thin layer of rhodamine 6G as active material and of a switchable holographic mirror, based on a reflection grating made of polymer dispersed liquid crystals. It is shown that switching-off the mirror reflectivity by application of a suitable voltage allows wavelength flipping of the laser emission by 10 nm.

In this work, we present the experimental evidence of a polarity sensitive electro-optic response in a nematic liquid crystal. The liquid crystal cell was made by using a standard sandwich configuration, with one of the indium tin oxide electrodes covered by a thin layer of tungsten trioxide (WO3), deposited by sputtering. The optical response was inhibited when the electrode covered by WO3 film was anodically charged, while the usual optical response occurred under a reverse field. An ionic diffusion process was associated with the establishment of an internal electric field, which inhibited unipolarly the optical switching.

A polarity sensitive electrooptical effect has been observed in nematic liquid crystal–polymer mixtures where a gradient of the polymer network density is created by strongly absorbed ultraviolet light. The effect is accounted for by a model based upon consideration of the space charge distribution caused by the polymerization process. The effect may be of interest for practical applications in optical shutters and electrically controlled windows.