Chen Yinfang, Wang Rong, Pu Tao, Zhen Fei, Zhu Yong, Fang Tao, Meng Nan, Zheng Jilin. Experimental Demonstration of Measuring Optical Threshold in Nonlinear Optical Loop Mirror Based on Variable Pulse Duty Cycle[J]. Chinese Journal of Lasers, 2012, 39(6): 605004