Mechanisms of optical losses in polycrystalline KRS-5 fibers

The widening of distribution of the laser radiation transmitted through the polycrystalline KRS-5 fiber which leads to the domination of the surface scattering and absorption in the total optical losses has been measured. It has been found from the obtained data that the value of the loss increases with the number of reflections at the side fiber surface per unit length of the fiber. Scanning electron microscopy of the side surface has shown the presence of hollows along the grain boundaries and other surface imperfections.