High diffraction efficiency in permanent optical memories based on Methyl Red doped liquid crystal

Abstract

This paper proposes a method for enhancing diffraction efficiency in an existing grating by re-illumination of the sample with a secondary pump beam. Though this single-armed pump beam is typically used to erase the grating, in specific conditions, as in our case for Methyl Red doped liquid crystal, it increases the diffraction efficiency. Describing physical background of this enhancement based on the molecules reorientation, high diffraction efficiencies (around 11.5 %) are reported which are not obtainable during the grating formation, even after long exposure times. Concerning the permanency of the obtained efficiency, this system may find various applications in read-only optical data storage devices.