Relaxation effect of stilbene azobenzene derivatives on their holographic properties

The material relaxation effect on holographic properties of stilbene azobenzene derivatives in the form of glassy films has been experimentally studied. Holographic grating recording with the period of 2 μm was made by a He-Ne laser at 633 nm in the self-diffraction mode. The readout was made simultaneously in order to follow the fast self-diffraction efficiency changes. The existence of the optimal material storage time (6-51 day) is established enabling the most efficient recording. Material relaxation amplitude and the holographic recording efficiency increased when the chromophore concentration was increased, especially above the threshold of about 70 mass %. It is also found that 633 nm recording due to the modulation of refraction and absorption indices is accompanied by the formation of surface relief grating. The conclusion is made that holographic recording in stilbene azobenzene derivatives at 633 nm is due to the chromophore reorientation by linearly polarized light possibly including trans-cis-trans transformations