Delivery of erbium: YAG laser radiation through side-firing germanium oxide fibers

Anthony K. Ngo, Nathaniel M. Fried

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


The Erbium:YAG laser is currently being tested experimentally for endoscopic applications in urology, including more efficient laser lithotripsy and more precise incision of urethral strictures than the HolmiunrYAG laser. While side-firing silica fibers are available for use with the Ho:YAG laser in urology, no such fibers exist for use with the Er:YAG laser. These applications may benefit from the availability of a side-firing, mid-infrared optical fiber capable of delivering the laser radiation at a 90-degree angle to the tissue. The objective of this study is to describe the simple construction and characterization of a side-firing germanium oxide fiber for potential use in endoscopic laser surgery. Side-firing fibers were constructed from 450-μm-core germanium oxide fibers of 1.45-m-length by polishing the distal tip at a 45-degree angle and placing a 1-cm-long protective quartz cap over the fiber tip. Er:YAG laser radiation with a wavelength of 2.94 μm, pulse duration of 300 μs, pulse repetition rate of 3 Hz, and pulse energies of from 5 to 550 mJ was coupled into the fibers. The fiber transmission rate and damage threshold measured 48±4 % and 149 ± 37 mJ, respectively (n = 6 fibers). By comparison, fiber transmission through normal germanium oxide trunk fibers measured 66 ± 3 %, with no observed damage (n = 5 fibers). Sufficient pulse energies were transmitted through the side-firing fibers for contact tissue ablation. Although these initial tests are promising, further studies will need to be conducted, focusing on assembly of more flexible, smaller diameter fibers, fiber bending transmission tests, long-term fiber reliability tests, and improvement of the fiber output spatial beam profile.

Original languageEnglish (US)
Title of host publicationProgress in Biomedical Optics and Imaging - Proceedings of SPIE
StatePublished - 2006
EventOptical Fibers and Sensors for Medical Diagnostics and Treatment Applications VI - San Jose, CA, United States
Duration: Jan 21 2006Jan 22 2006


OtherOptical Fibers and Sensors for Medical Diagnostics and Treatment Applications VI
Country/TerritoryUnited States
CitySan Jose, CA


  • Ablation
  • Endoscopic
  • Erbium
  • Fiber
  • Germanium
  • Mid-infrared
  • Sculpted
  • Side-firing
  • Urology

ASJC Scopus subject areas

  • Engineering(all)


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