光阈值器件是多用户光码分多址(OCDMA)系统接收机中抑制基底噪声和互相关旁瓣峰的重要部件。非线性光环镜(NOLM)是实现光阈值的一种有效方法。对基于高非线性光纤(HNLF)NOLM的阈值特性进行了实验研究及数据分析,提出利用改变抽运脉冲占空比分析阈值特性的方法,实验发现抽运脉冲占空比D为1/25时出现阈值点,阈值功率为3.75W。讨论了抽运光与信号光的波长间隔对NOLM输出信号的影响,得出阈值点处的最优波长间隔为5.8nm,脉冲压缩量为114.47ps。实验搭建了接收机阈值系统,眼图分析表明该系统能较好地抑制噪声。 Optical threshold devices are important components of sidelobe suppression in the receiver of multi-user Optical Code Division Multiple Access (OCDMA) systems. Non-linear halo mirrors (NOLMs) are an effective way to achieve optical thresholds. The threshold characteristics of NOLM based on highly nonlinear fiber (HNLF) are studied experimentally and analyzed. The method of changing the threshold characteristic of duty cycle of pumping pulse is proposed. It is found that when the duty cycle D of pumping pulse is 1/25 A threshold point appears with a threshold power of 3.75W. The influence of the wavelength interval between pump light and signal light on the NOLM output signal is discussed. The optimal wavelength interval at the threshold point is 5.8 nm and the pulse compression is 114.47 ps. The experimental setup of the receiver threshold system, eye diagram analysis shows that the system can better suppress the noise.