Improvement of transmission properties for a rugged polymer-coated silver hollow fiber

Abstract

An extremely rugged hollow fiber is fabricated by liquid-phase coating technique. A silica glass capillary is used as the substrate and vitreous film is firstly coated on the inner surface of the capillary to protect the glass tube from moisture. This protective coating keeps the thin-wall glass tube away from damage due to the following silver plating process. The additional transmission loss caused by the roughness of the protective film is decreased by limiting the length of the protective film. The whole length of 0.7-mm-bore hollow fiber was 1.2 m and the length of the rugged part which formed the protective film was only 30 cm. Transmission properties of the rugged polymer-coated silver hollow fibers for the Er:YAG laser and red pilot beam delivery have been improved. The loss for the 0.7-μm-bore size, 1.2-m-length rugged polymer-coated silver hollow fiber was 1 dB and 6.9 dB under straight condition, and 1.9 dB and 9.4 dB under the condition of a 270 degree bend with a 15-mm bending radius at the wavelength of 2.94 μm and 650 nm, respectively.