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.