Hollow glass waveguides are an increasingly popular fiber for the delivery of high-power IR laser radiation. At CO2 laser wavelengths the measured and theoretical losses agree, but at the 3-µm Er:YAG laser wavelength the losses remain higher than expected. The reason for this is the surface roughness of the silver film used to form the first layer of the Ag/AgI thin-film structure. We found that the roughness of the silver film increases fivefold as silvering times increase from 5 to 80 min. This increased surface roughness produces a concomitant linear increase in the attenuation coefficient for the silver-only guides for wavelengths shorter than approximately 5 µm.
© 1999 Optical Society of America
Original Manuscript: December 22, 1998
Revised Manuscript: March 29, 1999
Published: July 20, 1999
Christopher D. Rabii, Daniel J. Gibson, and James A. Harrington, "Processing and characterization of silver films used to fabricate hollow glass waveguides," Appl. Opt. 38, 4486-4493 (1999)