中国物理B ›› 2014, Vol. 23 ›› Issue (4): 44214-044214.doi: 10.1088/1674-1056/23/4/044214
• ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS • 上一篇 下一篇
刘明a b, 张海涛a, 巩马理a, 赵跃进b, 程文雍a, 孟阔a, 郑超a, 陈倚竹a
Liu Ming (刘明)a b, Zhang Hai-Tao (张海涛)a, Gong Ma-Li (巩马理)a, Zhao Yue-Jin (赵跃进)b, Cheng Wen-Yong (程文雍)a, Meng Kuo (孟阔)a, Zheng Chao (郑超)a, Chen Yi-Zhu (陈倚竹)a
摘要: A theoretical analysis of noise in a high-power cascaded fiber amplifier is presented. Unlike the noise theory in low power communication, the noise of a high power system is redefined as the leaked output energy between pulses with coherent beat noise uncounted. This definition is more appropriate for high power usage in which the pulse energy receives more attention than the pulse shape integrity. Then the low power pre-amplifying stages are considered as linear amplification and analyzed by linear theory. In the high-power amplification stages, the inversion is assumed to recover linearly in the time interval between pulses. The time shape of the output pulse is different from that of the input signal because of different gains at the front and back ends of the pulse. Then, a criterion is provided to distinguish the nonlinear and linear amplifications based on the signal-to-noise ratio (SNR) analysis. Then, an experiment that shows that the output SNR actually drops off in nonlinear amplification is performed. The change in the noise factor can be well evaluated by pulse shape distortion.
中图分类号: (Fiber lasers)