Recently High Electron Mobility Transistor (HEMT) inspired III-V electro-optic modulator topologies were proposed for realizing high speed electro-optic modulators leveraging plasma dispersion effect due to the 2D Electron Gas (2DEG) present at the III-V heterostructure interface. The 2DEG is highly confined at the interface, extending to very low depths in the bulk ($\approx$10nm) and therefore has limited spatial overlap with the optical mode. In this paper, we propose a novel modulator design to boost the 2DEG-light interaction, wherein the HEMT is embedded within a high contrast grating (HCG) mirror. We present an analytical model extending the conventional HCG model to multi-layer structures and observe good agreement with rigorous coupled-wave analysis (RCWA). We explore the design space for identifying optimal device topology and present geometries that produce a change in reflectivity as large as 70% for C- and L-band wavelengths. We also present results of sensitivity analysis and observe low variation in device performance due to geometry variation arising from device fabrication imperfections. The device platforms presented here are suitable for designing high efficiency electro-optic modulators by incorporating the HEMT HCG into a Fabry-Perot cavity.

中文翻译：

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基于 AlGaN/GaN 异质结构中高对比度光栅 (HCG) 的电光调制器的设计和分析

最近，人们提出了受高电子迁移率晶体管 (HEMT) 启发的 III-V 族电光调制器拓扑结构，以利用因 III-V 族异质结界面处存在的 2D 电子气 (2DEG) 而产生的等离子体色散效应来实现高速电光调制器。2DEG 高度限制在界面处，在体中延伸到非常低的深度（约 10 纳米），因此与光学模式的空间重叠有限。在本文中，我们提出了一种新颖的调制器设计来增强 2DEG 光相互作用，其中 HEMT 嵌入在高对比度光栅 (HCG) 镜中。我们提出了一种将传统 HCG 模型扩展到多层结构的分析模型，并观察到与严格耦合波分析 (RCWA) 的良好一致性。我们探索了用于确定最佳器件拓扑结构的设计空间，并展示了对 C 波段和 L 波段波长产生高达 70% 的反射率变化的几何形状。我们还展示了灵敏度分析的结果，并观察到由于设备制造缺陷引起的几何变化导致的设备性能变化很小。此处介绍的设备平台适用于通过将 HEMT HCG 集成到法布里-珀罗腔中来设计高效电光调制器。