Photorefractivity in Ferroelectric Liquid Crystal Composites Containing Electron Donor and Acceptor Molecules

Abstract

The first observation of photorefractivity in ferroelectric liquid crystals (FLCs) is reported here. Dopant chromophores chosen to optimize production of mobile ions and careful control of the wavevector and light polarization are believed to play a decisive role in the observed behavior. The Figure is a schematic illustration of the experimental geometry used.

Formation of Dynamic Hologram in Photorefractive Ferroelectric Liquid Crystals

“…[7][8][9][10][11][12][13] FLCs exhibit a chiral smectic C phase (SmC*) that possesses a helical structure. [14] When the FLC is sandwiched between glass plates to form a film of few micrometers thick, the helical structure uncoils and a surface-stabilized state (SS-state) is formed in which spontaneous polarization (Ps) appears.…”

Photorefractive Effect in Ferroelectric Liquid Crystals

“…The photorefractive effect in an FLC was first reported by Wasielewsky et al in 2000 [11]. Since then, details of photorefractivity in FLC materials have been further investigated by Sasaki et al and Golemme et al [12][13][14].…”

“…Thus, a refractive index grating (or hologram) is formed. One material class that exhibits high photorefractivity is that of glassy photoconductive polymers doped with high concentrations of D-π-A chromophores, in which donor and acceptor groups are attached to a π- Ferroelectric liquid crystals are expected to be used as high performance photorefractive materials [11][12][13]. A photorefractive ferroelectric liquid crystal with a fast response of 5 ms has been reported [14].…”

Dynamic Amplification of Optical Signals by Photorefractive Ferroelectric Liquid Crystals

“…Investigations into the photorefractive effect of FLCs started in the year 2000 [12,13]; the photorefractive FLC is a mixture of FLC and photoconductive compounds. Further details of the photorefractivity in FLC materials have since been investigated by Sasaki et al and Talarico et al [14][15][16][17][18][19].…”

“…It was found that a large photorefractivity was obtained with the application of low activation voltage (a few volts). The photorefractivity of ferroelectric liquid crystals doped with photoconductive compounds has been reported [12][13][14]. FLCs are considered to be candidates for practical photorefractive materials.…”