New glassy liquid crystals for optical data-storage applications

Low-molar-mass liquid crystals consisting of a binary nematic mixture of two-naphthylester which exhibit an anisotropic glassy state at room temperature have recently proven to be a suitable material for erasable optical data-storage applications. Using the holographic-grating technique, it is shown that more than 1000 all-optical write, read and erase cycles can be realized without remarkable loss of reversibility. The recording intensities are of the order of 100 W/cm² and optical erasure can be achieved with about twice that intensity. The times for recording and erasure of the optical gratings range on the millisecond scale and the stored gratings persist several months with a diffraction efficiency of typically 1 %. The spatial resolution has been proven down to 2 µm so far. The obtained results are compared with other reversible recording materials.