Permanent grating induced by nonlinear absorption in polysilane films

Abstract
The optical grating memory effect in polysilane film is investigated. A refractive index grating is formed within a few minutes by using visible light near room temperature. The grating formation time is dominated by the peak intensity of the pumping beams, and its dependence on the wavelength of the pumping beams corresponds to the two-photon absorption spectrum. The grating formation mechanism is explained as the result of the chain scission induced by two-photon absorption.