Degradation-induced transmission losses in silica optical fibers.

摘要

BACKGROUND AND OBJECTIVE: The interaction of surgical optical fibers with tissue has been studied. STUDY DESIGN/METHODS AND MATERIALS: Fibers (600 microns) were lased in chicken and beef tissue using a Nd:YAG laser from 5 to 50 W in both cw and pulsed modes. RESULTS: With longer lasing and higher power, larger transmission loss and degradation (burn-in) of the fiber tip, occurred. This degradation converts the Nd:YAG laser power to heat and leads to further energy loss. During contact lasing, tissue and blood adhere to the fiber tip surface limiting laser transmission, desiccating, and eventually destroying adhering tissues. Such tissue residues create high power densities and temperatures at the tip, which then cause a variety of degradation processes to be initiated. CONCLUSION: "Burned-in" fibers do not photocoagulate; rather they incise tissue. With continued lasing, thermal shock, chemical, and mechanical breakdown of the fiber leads to failure of the fiber tip and the spalling of glass fragments into the tissue bed.