Compact mid-infrared dual-comb spectrometer over 3–4 μm via intra-pulse difference frequency generation in LiNbO3 waveguides

• Published in: High power laser science and engineering 2024-01, Vol.12
• Main Authors: Zhou, Lian, Lou, Haipeng, Deng, Zejiang, Xiong Qin, Pan, Jiayi, Yuanfeng Di, Gu, Chenglin, Luo, Daping, Li, Wenxue
• Format: Article
• Language: English
• Subjects: Cameras; difference frequency generation; dual-comb spectroscopy; Efficiency; Fiber lasers; Gas sensors; Gases; Infrared lasers; Infrared spectrometers; Lasers; Lithium niobates; mid-infrared gas sensing; nonlinear optics; Optical frequency; Power; Spectrum allocation; Spectrum analysis; Waveguides
• ISSN: 2095-4719; 2052-3289
• DOI: 10.1017/hpl.2024.2

The mid-infrared optical frequency comb is a powerful tool for gas sensing. In this study, we demonstrate a simple mid-infrared dual-comb spectrometer covering 3–4 μm in LiNbO3 waveguides. Based on a low-power fiber laser system, the mid-infrared comb is achieved via intra-pulse difference frequency generation in the LiNbO3 waveguide. We construct pre-chirp management before supercontinuum generation to control spatiotemporal alignment for pump and signal pulses. The supercontinuum is directly coupled into a chirped periodically poled LiNbO3 waveguide for the 3–4 μm idler generation. A mid-infrared dual-comb spectrometer based on this approach provides a 100 MHz resolution over 25 THz coverage. To evaluate the applicability for spectroscopy, we measure the methane spectrum using the dual-comb spectrometer. The measured results are consistent with the HITRAN database, in which the root mean square of the residual is 3.2%. This proposed method is expected to develop integrated and robust mid-infrared dual-comb spectrometers on chip for sensing.