Efficient and broadband subwavelength grating coupler for 3.7 μm mid-infrared silicon photonics integration

• Main Authors: Chen, Nan, Dong, Bowei, Luo, Xianshu, Wang, Hong, Singh, Navab, Lo, Guo-Qiang, Lee, Chengkuo
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2019
• Subjects: DRNTU::Engineering::Electrical and electronic engineering; Silicon Photonics Integration; Grating Coupler
• Online Access: https://hdl.handle.net/10356/81309; http://hdl.handle.net/10220/47487
• Institution: Nanyang Technological University

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.