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

Periodic structures with a period d a parts per thousand 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 (lambda a parts per thousand 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.