Polarization-Controlled Bicolor Recording Enhances Holographic Memory in Ag/TiO₂ Nanocomposite Films

Abstract

Ag/TiO₂ nanocomposite films present a stable optical memory based on localized surface plasmon resonance but still suffer from the problem of the low efficiency of holographic storage. Here, we report that the response time and diffraction efficiency of the high-density holographic storage of Ag/TiO₂ nanocomposite films at 403.4 nm can be improved significantly and further modulated by introducing the auxiliary 532 nm irradiation with <i>s</i> or <i>p</i> linear polarization state. Absorbance at ∼600 nm, contrast of holographic fringes, and brightness of reconstruction image were all enhanced under the bicolor excitation. The observations were explained by Ag⁺ ions migration, Ag nanoparticle dissolution, and their redeposition, with the help of concentration and electronic-field gradient forces. Taking these factors in account, a phenomenological model describing the growth of two competitive-phase gratings is proposed. The localized surface plasmon resonance with the composite wave provides new possibilities for Ag/TiO₂ nanocomposite films in application of long-life and high-density optical memory