Side-firing germanium oxide optical fibers for use with erbium: YAG laser

Background and Purpose: During recent experimental studies, the erbium:YAG laser has been shown to be more efficient for lithotripsy and more precise for incision of soft urinary tissues than the conventional holmium:YAG laser. Mid-infrared optical fibers are being developed to allow endoscopic delivery of Er:YAG laser radiation. This paper describes the simple construction and characterization of a side-firing germanium oxide fiber for potential use with the Er:YAG laser in endourology. Materials and Methods: The 450-μm-core side-firing fibers were constructed from germanium oxide fibers by polishing the distal tip at a 45° angle and placing a protective quartz cap over the tip. The Er:YAG laser radiation, with a wavelength of 2.94 μm, was transmitted through the fibers. Results and Conclusion: The fiber transmission rate and damage threshold measured 48 ± 4% and 149 ± 37 mJ, respectively (n = 6 fibers). Sufficient pulse energies were transmitted through the side-firing fibers to produce contact tissue ablation.