基于色散光纤环级联结构的可调谐带通微波光子滤波器

Bandpass-tunable Microwave Photonic Filter Based on Dispersion Fiber Loops with Cascaded Structure

提出并验证了一种宽调谐带宽的带通微波光子滤波器设计方案。该滤波器借助可调谐光纤光栅Sagnac环对宽带光源进行均匀切割,产生波长间隔可调的连续光载波作为滤波器的抽头,结合色散光纤环级联结构,实现滤波器的可重构性。研究结果表明,在光电调制器和光电探测器的频率带宽足够大的情况下,当光纤光栅Sagnac环的臂长差在0.50～8.28mm内变化、可调谐光纤延迟线的最小变化步长为0.01mm时,该方案能够实现滤波器中心频率在8.050 6～1 333.200 0GHz内调谐,调谐步长为161.01MHz,边瓣抑制比达到27dB。

A design of tunable bandpass microwave photonic filter with wide tuning range was proposed and verified.The filter uses the tunable fiber grating Sagnac loop to make even cut of the broadband light source,generating continuous optical carrier with adjustable wavelength spacing as the taps of the filter,the reconfigurability of the filter is realized with the cascade structure of dispersion fiber loops.Test results show that when the frequency bandwidth of the optoelectronic modulator and photodetector is large enough,the arm length difference of fiber grating Sagnac loop varies in 0.50~8.28 mm and the minimum change step of the tunable fiber delay line is 0.01 mm,the central frequency of the filter can be tuned in 8.050 6~1 333.200 0 GHz,with a frequency tuning step of 161.01 MHz and a side mode rejection ratio of27 dB.