提出了一个新的基于布里渊散射效应的微波光子滤波器。该滤波器可通过调谐系统中光滤波器的中心波长,实现高解析度带通滤波器与陷波滤波器之间的灵活切换,并且通过调谐产生受激布里渊散射的泵浦光的波长可实现滤波器通带或阻带的中心频率在很大频率范围内连续调谐。该滤波器为全光结构,因此具有非常大的调谐范围(调谐上限仅受限于试验中使用的矢量网络分析仪的显示频率上限)。系统中采用相位调制器,因此没有偏置电压漂移问题。实验结果展示了一个带通与陷波滤可灵活切换的高解析度微波光子滤波器,并且通带和阻带的中心频率在9~26.5 GHz范围内连续可调谐,其中带通滤波器的通带具有极窄3 dB带宽,约28 MHz(由光纤本身布里渊增益区线宽所决定)。

A new microwave photonic filter based on stimulated Brillouin scattering was proposed. By tuning the center wavelength of the optical filter, the switchability between the microwave photonic bandpass filter and the microwave photonic notch filter can be obtained. The passband or the notch center frequency of the microwave photonic filter can be tuned continuously by tuning the wavelength of the pump laser. Since no electrical component was involved, the microwave photonic filter was all-optical. Therefore it can achieve a very broadband operating frequency range. The maximum measured tuning frequency range in the experiment was limited by the displaying range of the vector network analyzer. Since an optical phase modulator was used, no bias voltage was needed. Therefore, there was no bias voltage drift problem. Experimental results demonstrate a switchable and continuously tunable microwave photonic filter with a broadband operating frequency range from 9-26.5 GHz. The bandpass filter has a narrow 3 dB bandwidth up to 28 MHz, which is limited by the optical fiber Brillouin gain linewidth.