Optical Properties of Silver-Halide Core/Clad IR Fibers.

Optical fibers with low transmission losses are very useful in medical endoscopic laser surgery. In the past we developed unclad silver halide IR fibers for the transmission of CO₂ laser energy. We have recently developed core/clad polycrystalline silver halide optical fibers with a loss of roughly 0.3 dB/m at 10.6 μm. Such fibers, with a core diameter 0.35-0.6mm and length of 1 to 2 meters are capable of continuously delivering output power densities as high as 14 KW/cm2. We have studied the transmission properties of these fibers for different launching conditions such as the acceptance angle at the input end and the near and far field distributions at the output end. We have also investigated the effects of bending on the optical transmission. We show that by properly designing the core/clad structure we obtain significant improvements with respect to unclad IR fibers.