Infrared hollow optical fibers and their applications in medicine

Techniques for coating hollow glass fibers with layers of silver and cyclic olefin polymer have been developed for low-loss delivery of infrared laser light as well as a visible pilot beam. They have yielded losses of only 0.2 dB/m for Er:YAG and CO₂ laser light and only 0.7 dB/m for red LD laser light. Debris is kept from entering the hollow output end of a fiber by hermitically sealing it with a quartz cap, and various focusing effects in both air and water have been obtained by controlling distal-end geometry of the caps during fabrication. Controlled focus patterns of Er:YAG laser light with an output energy of more than 400 mJ and a 10-Hz repetition rate have been delivered in saline through the fibers with sealing caps. Calculi were fragmented in vitro by using a hollow fiber with a sealing cap. It has been shown that Er:YAG laser combined with an effective delivery system could be used for minimally invasive calculi fragmentation.