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基于耦合波理论,提出了一种推导反射体布拉格光栅衍射效率方程的新方法。在被推导的衍射效率方程基础上,获得了平面单色和高斯光束反射体布拉格光栅衍射的详细理论模型,分析了平面单色、发散单色和多色光束的衍射效率。结果表明:平面单色波的角和谱选择性随光栅厚度和空间频率而变化,角选择性的范围从低于0.01mrad到超过100mrad,谱选择性的范围从低于0.1nm到超过100nm;当光束的角发散或谱宽等于光栅的角选择或谱选择性时,光栅能提供超过88%的衍射效率;当光束的角发散或谱宽远小于光栅的角选择或谱选择性时,光栅衍射效率下降不明显,不到平面单色波的1%。
Based on the coupled wave theory, a new method to derive the diffraction efficiency equation of reflector Bragg grating is proposed. Based on the deduced diffraction efficiency equation, a detailed theoretical model of Bragg grating diffraction of plane monochromatic and Gaussian beam reflectors is obtained, and the diffraction efficiencies of planar monochromatic, divergent monochromatic and polychromatic beams are analyzed. The results show that the angular and spectral selectivity of planar monochromatic wave varies with grating thickness and spatial frequency. The angular selectivity ranges from less than 0.01 mrad to over 100 mrad, and the spectral selectivity ranges from less than 0.1 nm to more than 100 nm. Gratings provide more than 88% diffraction efficiency when the angular divergence or spectral width of the beam equals the angular or spectral selectivity of the grating; when the angular divergence or spectral width of the beam is much smaller than the angular or spectral selectivity of the grating, Diffraction efficiency is not significantly reduced, less than 1% of plane monochromatic wave.