Investigation on roughness of silver thin films inside silica capillaries for hollow waveguides

Abstract

A metal (Ag)/dielectric (AgI) hollow glass waveguide is a novel and flexible fiber for the delivery of high-power IR laser radiation. The surface roughness of the Ag films is one of the key factors that greatly influence the attenuation of the waveguides. In this paper, with the wet chemistry deposition, Ag thin films were successfully fabricated in silica capillaries, whose inner diameter was 0.53 mm. By means of atomic force microscopy (AFM), the metallization process and roughness of the Ag thin films were analyzed. It can be concluded that as the volume of AgNO 3 solution increased, the needed silver deposition time increased, and the size of the Ag grains enlarged, resulting in an incremental increase in the surface roughness of the Ag thin films. IR transmission results show that the attenuation of the waveguides increases with an increase in the surface roughness of the Ag thin films and augments when the input power increases.