Theoretical study of bicharacteristic waveguide for fundamental-mode phase-matched SHG from MIR to NIR

• Main Authors: Huang, Tianye, Xu, Guizhen, Pan, Jianxing, Cheng, Zhuo, Shum, Perry Ping, Brambilla, Gilberto
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2019
• Subjects: Coupled Mode Theory; Engineering::Electrical and electronic engineering; Phase Matching
• Online Access: https://hdl.handle.net/10356/106844; http://hdl.handle.net/10220/49663; http://dx.doi.org/10.1364/OE.27.015236
• Institution: Nanyang Technological University

In this paper, a bicharacteristic waveguide (BW) is proposed for fundamental-mode phase-matched second harmonic generation (SHG) from mid-infrared (MIR) to near-infrared (NIR). The required phase matching condition (PMC) is satisfied between the fundamental plasmonic mode at 3100 nm and the photonic mode at 1550 nm. With 1 W pump power, the SHG conversion efficiency of 4.173% can be obtained in 90.3 μm length waveguide. Moreover, the SHG conversion can be enhanced by using a microring resonator (MRR). By optimizing the MRR, the SHG conversion efficiency is increased to 8.30%. The proposed waveguide can also provide a promising platform for upconversion detection. By using an on-chip cascaded configuration, a gas sensor with the capability of MIR absorption and NIR detection is proposed. It is found that the detection limit (DL) can reach 1.04 nmol/L with 100 mW pump power, which shows significant enhancement compared with direct MIR absorption and detection.