Electrical Erasing of Holographic Grating in Amorphous Chalcogenide Thin Films

We investigated the electrical erasing of information recorded by a holographic method in an amorphous As₄₀Ge₁₀Se₁₅S₃₅ chalcogenide thin film. Even though the amplitude of photoinduced birefringence (Δn) strongly depends on applied DC voltage (V_DC), the kinetics exhibits a tendency. For V_DC=0–3 V, Δn increases with increasing induction time and eventually saturates to its maximum (Δn_max) even though its saturation time and amplitude are not the same at different V_DC's. For V_DC>4, Δn increases rapidly at the start of the induction process (within several seconds), reaches Δn_max and then decreases very slowly. In addition, phase gratings in amorphous As₄₀Ge₁₀Se₁₅S₃₅ films were formed by the holographic method and diffraction efficiency (η) was monitored in real time. Immediately after reaches its maximum (η_max), a short pulse was applied to the sample which cause a marked decrease in diffraction efficiency (η=0.25%→η≪10^-3).