Beam combining of a broadly and continuously tunable quantum cascade laser

• Main Authors: Sun, Fangyuan, Li, Jinghao, Tan, Kian Hua, Wicaksono, Satrio, Chua, Yun Da, Wang, Chongwu, Dai, Mingjin, Voo, Roth Qin Gui, Yoon, Soon Fatt, Wang, Qi Jie
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2023
• Subjects: Engineering::Electrical and electronic engineering; Aspherical Lens; Beam Combining
• Online Access: https://hdl.handle.net/10356/165643
• Institution: Nanyang Technological University

We report a cost-efficient method to demonstrate the beam combining of five laser elements in an array of tunable slot waveguide quantum cascade lasers in the mid-infrared region at around 10 µm. An aspherical lens with five fine-tuned mini mirrors was employed to collimate the individual beams from the laser array. To verify the feasibility of this beam combining approach, the combined beams were coupled into a hollow-core fiber gas cell with a low numerical aperture (N.A.) of 0.03 and a coupling efficiency >= 0.82, for gas sensing of binary compound gases of ammonia and ethylene simultaneously.