Synthesis and optical storage properties of a thiophene-based holographic recording medium

Abstract

The results of the fabrication and optical data storage characteristics of a novel azothiophene polyester 9 for potential holographic storage are reported. The polyester is derived from an azothiophene diol 1 and diphenyl phthalate 8via in vacuo melt transesterification. Inclusion of a 5-methoxy-2-thienyl moiety generates a trans π–π* transition centered close to 405 nm. An investigation of the optical data storage characteristics of a solution cast film of azopolyester with a thickness of 65 µm is summarised. The optical anisotropy induced by a 532 nm frequency doubled YAG laser and probed at a wavelength of 633 nm outside the absorption band with a polarimeter reveals a very high induced anisotropy of 7 rad (laser intensity, 250 mW cm⁻²). The calculated birefringence of the film is 0.02 per micron. Maximum anisotropy is reached after approximately 70 s of irradiation. The induced anisotropy disappears at approximately 90 °C. Room temperature stable gratings can be inscribed with high diffraction efficiency.