基于啁啾相移FBG的宽调谐单通带微波光子滤波器

为扩大单通带微波光子滤波器(MPF)的可调谐 范围,提出了一种基于啁啾相移光纤光栅(PS-FBG) 的宽调谐单通带MPF。首先对普通PS-FBG的反射谱和基于普通PS-FBG的单通带MPF频率响应 进行了理 论和实验研究；然后,采用传输矩阵方法分析了啁啾PS-FBG的相移量、折射率调制深度以 及相移点位置 对其反射谱特性的影响,进而分析了对基于啁啾PS-FBG的单通带MPF频率响应的影响。结果 表明,调节可调谐激光 源的波长,可实现单通带频率的可调；相对于普通PS-FBG,啁啾PS-FBG扩大了反射谱带宽 ,从而单通带MPF扩大了可调谐范围。适当设计啁啾PS-FBG的相移点的位置,可以使单通带M PF的可调谐范围进一步增加。

A single-passband microwave photonic filter with a wide tunable range based on a chirped phase-shifted FBG

To widen the tunable range of the single-passband microwave photon ic filter (MPF),a single-passband MPF with a wide tunable range is proposed,and it is based on a chirped phase-shifted fiber Bragg grating (PS-FBG).Firstly,the characteristics of the reflective sp ectrum of a common PS-FBG and the frequency response of the single-passband MPF based on the common PS-F BG are theoretically and experimentally studied.Then,a method of the transfer matrix is employed to analyze the effects of the value of the phase shift,the depth of the refractive index modulation and t he location of the phase shift of the chirped PS-FBG on the characteristics of the reflective spectrum a nd further on the frequency response of the single-passband MPF based on the chirped PS-FBG.The tunabilit y of the central frequency of the single-passband filter is achieved by tuning the central wavel ength of a tunable laser source. Compared with the common PS-FBG,the bandwidth of the reflective spectrum of th e chirped PS-FBG is increased so that the tunable range of the single-passband MPF is widened.Th e location of the notch in the reflective spectrum of the chirped PS-FBG is properly designed,which can ma ke the tunable range of the single-passband MPF become wider.