Sun Zhumei, Zhou Changhe, Cao Hongchao, Wu Jun
J Opt Soc Am A Opt Image Sci Vis. 2015 Nov 1;32(11):1952-7. doi: 10.1364/JOSAA.32.001952.
A unified design for a 1×2 beam splitter of dielectric rectangular transmission gratings under the second Bragg incidence is theoretically investigated for TE- and TM-polarized light. The empirical equations of the relative grating parameters (ratio of the absolute one to incidence wavelength) for this design are also obtained with the simplified modal method (SMM). The influences of polarization of incident light and relative grating parameters on the performance of the beam splitter are thoroughly studied based on the SMM and rigorous coupled-wave analysis. Two specific gratings are demonstrated with an even split and high diffraction efficiency (>94% for TE polarization and >97% for the TM counterpart). The unified profiles of the 1×2 beam splitter are independent from the incidence wavelength since the refractive index of fused silica is roughly a constant over a wide range of wavelengths, which should be promising for future applications.
从理论上研究了在第二次布拉格入射下，用于TE和TM偏振光的介质矩形透射光栅1×2分束器的统一设计。还通过简化模态方法（SMM）获得了该设计的相对光栅参数（绝对值与入射波长之比）的经验方程。基于SMM和严格耦合波分析，深入研究了入射光偏振和相对光栅参数对分束器性能的影响。展示了两种具有均匀分光和高衍射效率的特定光栅（TE偏振时>94%，TM偏振时>97%）。由于熔融石英的折射率在很宽的波长范围内大致为常数，1×2分束器的统一轮廓与入射波长无关，这对未来应用应该很有前景。
