Periodic Structures Formed by Ag Nanoparticles in AgCl–Ag Film Waveguides Exposed to Violet Laser Light

Periodic structures with a period d ≈ 266 nm owing to excitation of waveguide modes are produced in a thin film AgCl–Ag composition by normally incident linearly polarized light from a semiconductor laser (λ ≈ 407 nm). The grooves in the periodic structure are formed by Ag nanoparticles oriented along the polarization direction E 0 . Dichroism with a gap at the laser wavelength is observed in absorption spectra of these films measured in polarized light. The dichroism is retained after chemical removal of the AgCl from the AgCl–Ag film. It is found that the absorption gap is related to conversion of the plasmon energy into the energy of a waveguide mode, while the dichroism is attributable to anisotropic absorption of the light by Ag nanoparticles distributed in the grooves of the periodic structures.