Tapered fiber relay for laser beam transportation

Based on a mode field coupling theory, a Gaussian approximation model to calculate the conversion efficiency of tapered fiber is presented. The simulation result is discussed and an experiment is conducted with 532 nm laser, multi-mode fiber (numerical aperture is 0.11, radius is 12.5 μm) and tapered-fiber (numerical aperture is 0.11, radius is (4±1)，(5±1)，(6±1)，(7±1) and (8±1) μm respectively) to measure conversion efficiency of tapered fiber. Good agreement is obtained between the experimental results and the theoretical calculations. A tapered fiber relay system is proposed to transport a laser beam with high power and good beam quality.