Reversible Storage of Light-Induced Gratings in Low Molar Mass Liquid Crystals

Low molar mass liquid crystals which exhibit an anisotropic glassy state are investigated for erasable recording processes. Optical gratings were written with intensities less than 1000 W/cm2 obtained from an argon-ion laser and read out by diffraction of a weak He-Ne laser. Grating build-up times of less than 5 ms have been observed. Diffraction efficiencies of several percents were measured as a function of intensity and grating periods down to 5μm. The stored gratings are erased by homogeneous laser heating. It is shown that the observed recording phenomena is connected with optical heating and light-induced transitions from the glassy to the liquid crystalline state of the material.