Photoinduced transformations in a thin-film waveguide AgCl-Ag composition under a green (532 nm) laser beam

A linearly polarized (E ₀) laser beam (λ = 532 nm) causes photoinduced transformations in an AgCl-Ag composition consisting of a thin waveguide AgCl film on glass covered by a layer of Ag nanoparticles. Before the illumination the sample exhibits an absorption band due to localized plasmons in nanoparticles. The illumination excites plasmons and leads to scattering of waveguide TE₀ modes. The interference of modes with the incident light beam leads to the development of a periodic structure, the lines of which are formed by Ag particles and directed along E ₀. The measured structure period coincides with the result of calculation based on solving the dispersion equation for the TE₀-mode. Measurement of absorption in the E ‖ E ₀ polarization reveals dichroism and a spectral hole (at λ ≈ nm). It is shown that the structures formed remain on the substrate after removing AgCl in a fixing agent. The dichroism value and dispersion change after fixing. The character of dichroism prior to fixing is recovered after depositing an AgCl layer (with the parameters retained) on the fixed film.