Effects of reflection of fiber end on characteristics of high power fiber amplifier

The reflectivity of the fiber ends was estimated by studying the technology of fiber end polishing and lapping. Based on rate and propagation equations of the Ybdoped fiber amplifier, the effect of the fiberend reflectivity on the output characteristics induced by the error of the polishing angle was simulated numerically. The results show that both reducing the reflectivity of the fiber end and increasing the power of the input signal can reduce the amplified spontaneous emission and restrain the selfoscillations. The performance of the high power fiber amplifier can be improved by choosing the angle of the fiber end inclined-surface polished and the power of the input signal properly．