Towards the Realization of Hollow-Core Silver Halide Fibers for Laser Angioplasty

In this study, we have demonstrated some preliminary results on the development of silver halide hollow-core Bragg fibers intended for the single-mode operation at the wavelength of 5.75 $\mu$ m, which is selectively absorbed by atherosclerotic plaques. We chose the target functional characteristics of the fibers and simulated their mode field distribution using finite element analysis. The optimal model consisted of AgCl$_{0.14} Br_{0.86}$ and AgCl$_{0.86} Br_{0.14}$ solid solution crystals and had the outer diameter of 700 $\mu$ m, whereas the core diameter was 300 $\mu$ m. It was found that the fiber possesses quite a large effective mode area and allows transmitting radiation with low optical losses. Such fibers may be very useful as laser delivering channels in medical applications since they are non-toxic, non-hygroscopic, biocompatible, and they are thin, long and flexible enough to insert them into catheters or cannulae. Due to high laser-induced damage threshold and low optical losses, these hollow-core fibers may be effectively used for low-invasive and highly precise laser angioplasty, and may significantly advance in vivo application of this technique.