Study of high-power and high-energy laser fiber coupler

The cause and mechanism of damage caused by input laser on fiber´s input end face are analysised in this paper, when high-power and highenergy laser input into. And a kind of special reflective fiber coupler is developed. It can change laser spot into a light disk whose dimension is equal to or less than the fiber section´s. The laser energy is evenly distributed on light disk and the laser power density is lower than laser fiber´s damage threshold. Making use of electrooptical Q-switching Nd:YAG laser whose output spike pulse´s peak power is 15 KW. Through experiment, the coupling efficiency can get to 80-85%. In addition, the fiber´s input end face is not damaged via longer work time. Then this device satisfies actual applying requirement.