Chen Nan, Dong Bowei, Luo Xianshu, Wang Hong, Singh Navab, Lo Guo-Qiang, Lee Chengkuo
Opt Express. 2018 Oct 1;26(20):26242-26256. doi: 10.1364/OE.26.026242.
A grating coupler is an essential building block for compact and flexible photonics integration. In order to meet the increasing demand of mid-infrared (MIR) integrated photonics for sensitive chemical/gas sensing, we report a silicon-on-insulator (SOI) based MIR subwavelength grating coupler (SWGC) operating in the 3.7 μm wavelength range. We provide the design guidelines of a uniform and apodized SWGC, followed by numerical simulations for design verification. We experimentally demonstrate both types of SWGC. The apodized SWGC enables high coupling efficiency of -6.477 dB/facet with 3 dB bandwidth of 199 nm, whereas the uniform SWGC shows larger 3dB bandwidth of 263.5 nm but slightly lower coupling efficiency of -7.371 dB/facet.
光栅耦合器是紧凑且灵活的光子集成的关键组件。为了满足中红外（MIR）集成光子学对灵敏化学/气体传感日益增长的需求，我们报道了一种基于绝缘体上硅（SOI）的工作在3.7μm波长范围的中红外亚波长光栅耦合器（SWGC）。我们给出了均匀和变迹SWGC的设计准则，随后进行数值模拟以验证设计。我们通过实验展示了这两种类型的SWGC。变迹SWGC实现了-6.477 dB/面的高耦合效率，3 dB带宽为199 nm，而均匀SWGC显示出更大的263.5 nm的3dB带宽，但耦合效率略低，为-7.371 dB/面。
