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

• couplers requiring secondary etching, the proposed full-etch grating coupler structure can reduce the complexity of fabrication and can provide a prospective platform for MIR photonic integration and photonic biosensor detection. Keywords: circular arc element; focusing grating coupler; germanium-on

• technological process. Therefore, a focusing grating coupler (FGC) with a simple fabrication process and high coupling efficiency is urgently needed. In this paper, a MIR FGC with a single circular arc element (CAE) based on Ge-on-Si is demonstrated and simulated. The proposed MIR FGC consists of a section of