BROAD-BAND FLEXIBLE WAVE-GUIDES FOR FREE-ELECTRON LASER-RADIATION

We refined flexible waveguides previously developed for CO2 and Er:YAG laser radiation to transmit free-electron-laser (FEL) radiation. One can tune this laser over several segments of the radiation spectrum. T his laser has a high peak power of as much as 10 MW with pulse energy of as much as 100 mJ. We made the waveguides of either Teflon pr fused -silica tubes internally coated with metal and dielectric layers. We o ptimised the internal coatings specifications for transmission of vari ous radiation wavelengths in the mid-IF range and enabled transmission of high-peak radiation. We performed experiments in three major FEL s ites in the United States over a more than 1-year period when we measu red and examined various characteristics of transmission. We used the analysis of these experiments as feedback to further improve these wav eguides. The good preliminary results encourage us to invest more effo rt to further develop these waveguides until a suitable waveguide is o btained for this type of laser and make possible its introduction to t he medical field where its characteristics can be exploited in surgica l applications. (C) 1997 Optical Society of America.