HOLLOW GLASS WAVE-GUIDES FOR BROAD-BAND INFRARED TRANSMISSION

Broadband hollow glass waveguides have been fabricated with losses as low as 0.15 dB/m at 10.6 mum. We make these hollow glass waveguides by coating the inside of polyimide-coated silica-glass tubing with a metallic layer followed by a thin dielectric coating of a metal halide. The bore sizes of the guides range from 320 to 700 mum, and we have made lengths as long as 3 m. The bending radii of the waveguides are less than 5 cm for bore sizes less than 500 mum. We have used these waveguides to deliver greater than 80 W of CO2 laser power and 5 W of Er:YAG laser power. The hollow glass guides are inexpensive, robust, and quite flexible and therefore a good infrared fiber for power and sensor applications.