平面非周期聚焦光栅的模拟设计

Design and Simulation of Non-period Planar Focusing Grating

使用严格耦合波分析和有限元模拟方法,设计了一种新颖的亚波长非周期高对比折射率光栅(HCG).该HCG的结构参数在1.55μm波长能同时满足在Si材料上制作聚焦反射镜和在Ga N材料上制作聚焦透镜,且具有符合微电子工艺的平面结构.模拟结果显示,2种HCG都具有大的数值孔径、很高的衍射系数和优秀的聚焦能力.由于具有相同的HCG结构参数,聚焦透镜和反射镜可以在制作工艺上使用同一光刻掩模版,这对需要聚焦功能的器件,尤其是Si和III族氮化物集成器件的设计制作,提供了极大的方便.

A novel subwavelength non-periodic high index contrast grating （HCG） structure is designed by rigorous coupled-wave analysis （RCWA） method and finite-element method （FEM）. At 1.55 μm wavelength, the HCG can serve as focusing reflector; when the grating bars material is Si, or as focusing lens when the grating bars mate- rial is GaN. Both reflectors and lenses have large numerical aperture （NA） , high diffraction efficiencies and excel- lent focusing ability. The reflector and the lens can be simply fabricated using lithography with same mask because of the identical structure, which greatly facilitates fabricating photonic devices that require focusing components, especially for the Si and Ⅲ-nitride integrated photonic devices.