Selective photo-oxidation induced bi-periodic plasmonic structures for high-density data storage.

Stable and controllable optical memory is necessary for the development of current information technology. In this context, Ag/TiO films have received much attention for their photosensitivity in wavelength and polarization, which can be applied to high-density optical storage. Here, we carried out dual-wavelength holographic recording using 403.4 nm and 532 nm lasers, and obtained mixed microfringes based on selective photodissolution of Ag nanoparticles of various sizes in TiO nanoporous films. Two recording methods of simultaneous and sequential multiplexing were investigated. It was found that using simultaneous irradiation it is easier to obtain equivalent efficiency in both spectral hole burning and multiplexed grating diffraction, compared with the sequential one. The results can be explained by the Time-accumulation effect during Ag ion diffusion and migration in holographic recordings. Based on such properties, multiplexed-holographic fringes with uniform contrast were reserved by simultaneous recording in Ag/TiO films. This work provides a new strategy for fabrication of photonic devices with complex microstructures.