<title>Hollow glass and plastic waveguides for the delivery of Er:YAG and CO<formula><inf><roman>2</roman></inf></formula> laser radiation</title>

Abstract

ABSTRACT Hollow glass waveguides are an attractive fiber delivery system for both the 3 tm Er:YAG and 10.6 im CO2 lasers. Thelosses for these waveguides are as low as 0.2 dB/m at CO2 laser wavelengths for guides with a 700 tm bore. At the shorterwavelengths of the Er:YAG laser the losses are higher than those predicted theoretically. This is shown to be a result ofsurface roughness of the inner coatings. These hollow guides are found to have losses which change little with time or cyclicflexure. A new version of these guides made from polycarbonate tubing is described and the losses for these guides areshown to compare favorably with those for the glass guides.Keywords: hollow waveguides, JR fibers, JR lasers, medical lasers, laser beam delivery, CO2 laser, Er:YAG laser 1. HOLLOW WAVEGUIDE FUNDAMENTALS Hollow-glass waveguides (HGW) that have internal metal and dielectric films aretoday one of the most attractive means of delivering Er:YAG and CO2 laser 12 These hollow-glass waveguides, usually with a metallic film of Ag and a singledielectric film of AgI or AgBr, have very low 10552 and high spatial purity of theoutput beam profile3 as a result of the smooth inner surface and the high uniformityin cross section of the glass tubing used as the base material. The structure of atypical HGW is shown in Fig. 1 .