光纤耦合器对光纤傅里叶变换光谱仪的影响

光纤耦合器是全光纤傅里叶变换光谱仪(FFTS)的关键元件.根据耦合模理论,分析了光纤耦合器的分束比、附加损耗等传输特性对FFTS的工作带宽和测量准确性的影响.提出一种修正方法,即根据耦合模理论,拓展光纤耦合器传输矩阵的定义,通过实验测量确定其值,进一步计算得到反映光纤耦合器传输光谱特性的窗形函数,用于FFTS的光谱修正.采用此修正方法不但拓宽了FFTS的工作带宽,提高了其测量准确性,而且降低了FFTS对光纤耦合器传输特性的要求.

Impacts on Optical Fiber Fourier Transform Spectrometer from Fiber Couplers

Couplers are key components in an optical fiber Fourier transform spectrometer (FFTS). According to the coupled-mode theory, the impacts of fiber couplers transmission characteristics such as splitting ratio and additional loss, on the veracity and bandwidth of FFTS are analyzed. A method to modify the impacts is put forward, the transfer matrix definition of coupler is expended, according to the coupled-mode theory. After the matrix value is achieved through experimental measurement, a window function reflecting the transmission characteristics of couplers is calculated. This modification on FFTS not only makes spectral range wider, improves the measurement veracity, but also lowers the FFTS′s demands for couplers.