Double-groove reflection gratings are proposed for three-channel beam separation under two polarizations at infrared laser wavelength. The double-groove grating profiles are analyzed by use of the finite element method. Incident laser light is reflected into the 0th and ±2nd orders equally for both TE and TM polarizations, which has the merit of polarization independence. The total diffraction efficiencies of three orders are more than 95% for each of two polarizations. Compared with the reported single-groove three-port grating, the double-groove grating has a wide incident bandwidth and a large tolerance of grating period. The presented reflection grating for three-channel beam separation should be a useful optical device at infrared wavelength in practical applications.

中文翻译：

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双槽反射光栅，用于红外波长的三通道光束分离

提出了双槽反射光栅，用于在红外激光波长的两个偏振下进行三通道光束分离。使用有限元方法分析了双槽光栅轮廓。对于TE和TM偏振，入射激光均被均匀反射到0级和±2级，这具有偏振独立性的优点。对于两个偏振中的每一个，三阶的总衍射效率都超过95％。与报道的单凹槽三端口光栅相比，双凹槽光栅具有宽的入射带宽和较大的光栅周期容差。提出的用于三通道光束分离的反射光栅在实际应用中应该是有用的红外波长的光学器件。