Stabilized Terahertz Quantum Cascade Laser Dual-Comb Sources with a Hybrid Locking

• DOI: 10.1021/acsphotonics.3c01379
• Publication Date: 2024-01-05T07:39:51Z
• Authors: Yiran Zhao; Ziping Li; Xuhong Ma; Kang Zhou; Wen Guan; Chenjie Wang; Shumin Wu; Han Liu; Wenjian Wan; J. C. Cao; Ya Zhang; Heping Zeng; Hua Li
• Keywords: Comb generator; Quantum cascade laser; Comb filter; Injection locking; Phase locking; Photomixing

Frequency combs show various application potentials in high precision spectroscopy, imaging, communications, and so on. In the terahertz (THz) region, semiconductor-based quantum cascade lasers (QCLs) are good candidates for frequency comb dual-comb operations. THz sources can be obtained by beating two QCL with a slight difference repetition frequencies. A free-running source normally shows relatively large phase noise, which strongly hinders its applications. Different approaches, e.g., digital algorithms, active locking of one line, self-reference techniques, etc., have already been employed to stabilize sources. Up now, complete using hardware elements has never demonstrated. Here, we propose hybrid method simultaneously both offset frequencies source. Experimental results demonstrate that stability all lines is improved significantly when proposed applied Under condition, measured "maxhold" line width reach record 5.7 kHz. Furthermore, recorded time trace signal pulse-like behavior during scale 100 μs, verifies functions well an