Optical holographic recording properties of l-(2-Pyridylazo)-2-Naphthol thin film

The optical holographic recording properties of the azo dye l-(2-Pyridylazo)-2-Naphthol in PMMA thin film were studied by using the three-dimensional forward degenerate four-wave mixing technique with a ps pulse laser at 532 nm. It demonstrated that the transient grating turned into a permanent grating with the increase of the pulse energy and the grating can be erased through a thermal treatment of the film. The mechanism of the fixed grating was attributed to the trans-cis isomerization of the azo molecules induced by singlet excited-state absorption and the subsequent orientation of the molecules.