光学频率梳空间光谱分辨精度研究

光学频率梳的高精度光谱整形在微波光子学、光谱学及通信光学等学科领域具有广泛应用. 为了描述和评价光学频率梳光谱整形系统的光谱分辨精度, 使用光线追迹的方法对单光栅、平行光栅对、单光栅透镜变换和反平行光栅 对透镜变换四种结构的空间色散能力进行了理论建模和分析, 得到了输出面上不同波长的光斑间距和光斑大小, 设立判据得到系统的光谱空间分离能力. 计算结果表明, 使用后面两种色散结构更容易实现高精度光谱分离和整形; 波长较长、纵模间距较大、光斑尺寸较大的光学频率梳更适合作为光谱整形系统的光源; 光栅刻线密度高、入射角小、多次通过色散系统有利于得到更高的光谱分辨精度. 本文的分析和计算过程具有普遍适用性, 对基于光学频率梳的高精度光谱整形系统的实验和评价具有指导意义.

Spatial dispersion of pulse shaping system with high resolution based on the frequency comb

High resolution pulse shaping based on the frequency comb has been widely used in microwave photonics, spectroscopy and communication optics and so on. To describe and evaluate the resolution capability of such a pulse shaping system, the ray tracing method is adopted to analyze the spatial dispersions of four schemes like single grating, parallel gratings, single grating with focus and anti-parallel gratings with focus. The spot spacings and sizes of different wavelengths can be determined from the modeling. As indicated by the calculation results, the latter two structures are advantageous to achieve high resolution pulse shaping; frequency combs with long wavelength, large mode spacing and big spot size are favorable for space dispersion; high grating groove density, small incident angle and multi passes in the dispersion system are conducible to the achievement of high resolution. The criterion for resolution would bring on some spot overlap noise.