Polarization dependence of holographic recording in glassy azocompounds

Polarization dependence of holographic grating recording in glassy molecular azobenzene films 8a, 11, and 16 has been experimentally studied at 633 and 532 nm with s-s, p-p, CE-1 and CE-2 circular-elliptic (differing by light electric field rotation directions) recording beam polarizations. Samples 8a and 11 with the simplest chemical structure were the most efficient at 633 nm, and sample 8a was the most efficient at 532 nm. Self-diffraction efficiency (SDE) up to 45% was achieved in 8a with p-p polarized recording beams at 633 nm. Linear p-p polarizations were the most efficient at 633 nm whereas CE-1 polarizations were the best at 532 nm. It was found that the light polarization changes in the process of diffraction depend on chemical composition, wavelength, and exposure time. Vector gratings with SDE up to 25% were recorded in 8a rotating a linear polarization by 90°. Mainly erasure of gratings took place with one beam. Coherent self-enhancement of gratings was observed only for s-p and both CE polarizations in 8a at 532 nm and for s-p polarizations at 633 nm. Atomic force microscopy measurements also were made. The evidence is found for trans-cis photoisomerization holographic recording mechanism at both 532 and 633 nm. Studied films can be applied for production of polarization holographic optical elements and for permanent optical information recording.