A reconfigurable and application-specific tunable microwave photonic filter having finite impulse response is proposed. The filter exploits the differential mode group delays of linearly polarized modes in a multi-mode fiber to achieve single and multiple high-frequency passband response. The filter taps are realized using a single continuous wave laser source and differential delays among modes that are propagated through a single spool of graded index multi-mode fiber. Depending upon the application requirement, different values of free spectral range of the microwave photonic filter are obtained by employing fiber spools of different lengths. The reconfigurability of the microwave photonic filter is achieved by varying the number of linearly polarized modes. It has been shown that the passband ripple can be reduced by employing higher order spatial modes and unequal power ratio among different modes. The proposed filter enables application-specific free spectra range tunability and reconfigurability along with added advantages of easy implementation and passband optimization.

提出了一种具有有限冲激响应的可重构且专用的可调谐微波光子滤波器。该滤波器利用多模光纤中线性偏振模的差模群时延来实现单个和多个高频通带响应。使用单个连续波激光源和通过渐变折射率多模光纤的单个线轴传播的模式之间的差分延迟来实现滤波器抽头。根据应用需求，通过使用不同长度的光纤线轴，可以获得微波光子滤波器的自由光谱范围的不同值。微波光子滤波器的可重构性是通过改变线性偏振模的数量来实现的。已经表明，通过采用高阶空间模式和不同模式之间不相等的功率比，可以减少通带纹波。所提出的滤波器实现了特定于应用的自由光谱范围的可调性和可重新配置性，以及易于实现和通带优化的其他优点。