提出了一种光子晶体光纤Sagnac环切割宽带光源的中心频率连续可调的微波光子滤波器.用温敏液体(Cat.19340)对光子晶体光纤(长度为5m)中心的一个大孔进行填充后嵌入Sagnac环.仿真分析了不同填充占空比对Sagnac环梳状谱周期和滤波器通带中心频率调谐范围的影响, 测得占空比越大, Sagnac环的梳状谱周期越小, 滤波器通带中心频率的调谐范围越大.在占空比最大的情况下,当温度为20℃和80℃时, Sagnac环的梳状谱周期分别为0.72 nm和0.52 nm, 用该Sagnac环对宽带光源进行切割, 当温度在20℃~80℃变化时, 多波长光源波长间隔在0.72 nm~0.52 nm连续可调, 实现了滤波器通带中心频率在15.5GHz~21.5GHz范围内连续可调.

A microwave photonic filter based on photonic crystal fiber Sagnac loop was presented, the filter′s center frequency can be continuously tunable. The length of photonic crystal fiber is 5m, using the thermo-sensitive liquid of Cat.19340 to fill one big hole of photonic crystal fiber and then embed it into Sagnac loop. The effect of different duty ratios to the period of comb spectra of Sagnac loop and the tuning range of the passband center frequency of the filter were analyzed. The measured results show that the larger the duty ratio, the smaller the period of comb spectra of Sagnac loop and the larger tuning range of the passband center frequency of the filter. In the case of the maximum duty ratio, the simulation measured period of comb spectra of Sagnac loop at the temperature of 20℃ and 80℃ are 0.72 nm and 0.52 nm respectively. Using the Sagnac loop to slice the broadband light source, by adjusting the thermo-sensitive liquid′s temperature from 20℃ to 80℃, the center frequency of the microwave photonic filter can be tuned continuously within the range of 15.5 GHz ~21.5GHz.