A mid-infrared focusing grating coupler with a single circular arc element based on germanium on silicon

• Xiaojun Zhu,
• Shuai Li,
• Ang Sun,
• Yongquan Pan,
• Wen Liu,
• Yue Wu,
• Guoan Zhang and
• Yuechun Shi

Beilstein J. Nanotechnol. 2023, 14, 478–484, doi:10.3762/bjnano.14.38

• , Nanjing University, Nanjing 210093, China 10.3762/bjnano.14.38 Abstract A mid-infrared (MIR) focusing grating coupler (FGC) with a single circular arc element (CAE) in the front of the gratings based on a germanium-on-silicon (Ge-on-Si) platform is designed and demonstrated. It can be used equivalently

• cover the wavelength of 6–15 μm. Hence, it is a suitable material for biosensors applications in the MIR band [6]. In recent years, researchers have verified the feasibility of Ge MIR waveguides on various substrate materials, such as germanium on silicon (Ge-on-Si), germanium on silicon-on-insulator

• (GOSI) [7], germanium on insulating substrate (GOI) [8][9], and germanium on silicon nitride substrate (GOSN) [10]. Among them, Ge-on-Si platforms have been widely applied in on-chip sensors, nonlinear optics, free space communication, and thermal imaging [1][6] because portable, cost-effective, and