Tapered and non-circular hollow glass waveguides

Linearly tapered hollow-glass waveguides (HGW) were fabricated using tapered silica glass tubing and wet chemistry techniques. Attenuation constants for these tapered HGWs were found to be higher than for similarly sized non-tapered HGWs, but the tapered guides showed reduced loss on bending. HGWs with rectangular and square cross-sections were also fabricated from non-circular bore silica glass tubing using wet chemistry techniques. These guides were able to maintain linear polarization of CO₂ laser light better than circular bore HGWs fabricated by the same methods, with as high as 97% of the input polarization preserved for a 227 μm×1253 μm bore guide. The non-circular bore HGWs had higher attenuation constants than similarly sized circular bore HGWs and sacrificed some spatial purity of the output beam.