CATASTROPHIC DAMAGE IN SPECIALTY OPTICAL FIBERS UNDER CW MEDIUM-POWER LASER RADIATION

摘要

We have investigated some features of the catastrophic damage propagating along fibers of different type under the action of laser radiation. All fibers investigated (silica based ordinary and microstructured fibers, fluoride and chalcogenide fibers) can be damaged by laser radiation, but the processes of destruction in silica based fibers and in fluoride and chalcogenide fibers are of quite different nature. The destruction process in silica based fibers is accompanied by the plasma (optical discharge) formation in the core region. In fluoride and chalcogenide fibers this process is characterized by thermal decomposition and embrace the whole cross-section of the fiber. For the first time the catastrophic damage in microstructured fibers has been investigated. For this type of fibers the threshold intensity for the catastrophic damage process is higher than that for conventional fibers. The phenomenon of silica fiber cladding destruction by the fiber fuse effect has been observed in the case of preliminary reduction of its mechanical strength. The cladding destruction leads to the termination of the optical discharge propagation in a fiber that can be used to confine the fiber fuse effect in fiber systems.