Transmission characteristics of infrared hollow fiber with multi- AgI and SiO₂ films are discussed. Three-dielectric-layer hollow glass fiber with SiO₂/AgI/SiO₂/Ag structure was fabricated for low-loss delivery of infrared laser light. The first SiO₂ film on the silver layer was coated by using liquid phase coating method. A semi-inorganic polymer was used as the coating material. A smooth vitreous film was formed by the treatment of a hardener at room temperature and followed by curing treatment. For the deposition of the AgI film between the two SiO₂ films, an Ag film was first plated on the SiO₂ film by silver mirror reaction method. Then the iodination process was conducted to turn the silver layer into silver iodide. The second SiO₂ layer was deposited on the AgI layer in the same way as the first SiO₂ layer. Fabrication parameters for controlling film thicknesses, such as iodination temperature, silver mirror reaction time, and solution concentration, are clarified for depositing AgI and SiO₂ films with the theoretical optimum thicknesses. By optimizing the thickness of the three dielectric layers, low-loss in the loss spectrum of SiO₂/AgI/SiO₂/Ag hollow glass waveguides can be obtained at the target infrared wavelengths. A method is proposed to evaluate the film thickness of AgI layer based on the positions of loss peaks and valleys in the loss spectra. Theoretical calculation for loss spectrum of SiO₂/AgI/SiO₂/Ag hollow glass fiber considering material dispersion of dielectric materials is also conducted. Good agreement with the measured data is demonstrated.

Date Published: 20 February 2009
PDF: 10 pages
Proc. SPIE 7173, Optical Fibers and Sensors for Medical Diagnostics and Treatment Applications IX, 71730G (20 February 2009); doi: 10.1117/12.807904

Published in SPIE Proceedings Vol. 7173:
Optical Fibers and Sensors for Medical Diagnostics and Treatment Applications IX
Israel Gannot, Editor(s)