Research On Couple Technology Of High-Power, High-Energy And Narrow-Pulse Laser With Optical Fiber

The coupling of laser with fiber has been used in many fields, such as industry, medical treatment, communications. At the present time, the coupling methods are mainly direct-coupling and lens coupling. For the existence of a damage threshold in fiber end face and interior, it is very difficult to use the above ways to realize the coupling of high-power, high-energy and narrow pulse laser with optical fiber.In this paper, on the basis of analyzing the mechanism of damage of optical fiber, a new method has been presented to reduce laser power density and energy density in optical fiber end face and interior and a hollow cone shaped laser-fiber coupler has been designed. When cylindrical Gauss beam incident into the hollow cone coupler, it will form a light spot which the energy density becomes quasi-average distribution. So the energy density of laser on the fiber end face has been reduced effectively. By using this coupler, the coupling of a high-power(lOMW), energy(12MJ), narrow pulse (12ns) and electro-optical Q-switched Nd:YAG laser with the multimode optical fiber (diameter is 600μm) has been realized and the coupling efficiency is 72%.