光通信波段亚波长光栅偏振器的设计与分析

Design and Analysis of Optical communication band Sub wavelength Grating Polarizer

摘要:

亚波长周期结构光栅具有传统光栅所不具有的特殊特性。基于矢量衍射理论 耦合波分析法对矩形亚波长光栅的衍射效率进行了理论计算，针对光通信中的1550nm波长设计了一种基于SOI 衬底的亚波长偏振光栅，分析了光栅周期、光栅深度、占空比和光栅结构的变化对其偏振特性的影响。仿真结果表明，当光栅的周期为960nm，槽深为230nm，占空比为24%时，可使TM 模式的透射率大于95%，TE 模式的透射率小于5%，且矩形的光栅结构相对于三角形和圆形的光栅结构具有更好的偏振性能，可有效用于光开关、光隔离器、激光器、光探测器等半导体光电子器件。

Abstract:

The sub-wavelength grating with a period structure has special characteristics compared to the traditional grating. A rectangle sub wavelength grating polarizer, which is applicable for the long-wavelength-band, was designed by the rigorous coupled-wave theory (RCWA) on the SOI substrate. It was analysed the trend curve of diffraction efficiency with grating parameters. Calculation results indicate that the diffraction efficiency of sub-wavelength grating changes with the period, the depth, the fill factor and the pattern of the grating. As the results show, the diffraction efficiency of TM mode is more than 95%, and the diffraction efficiency of TE mode is less than 5% when the period is 960nm, the depth is 230nm, and the fill factor is 24%. This kind of rectangle grating has better polarization properties compared with triangular and circular gratings, and it has great potential for applying in optical switching, optical memory, optical detectors and other semiconductor photoelectronic devices.