On-Chip Dual-Comb Source Based on Terahertz Quantum Cascade Lasers Under Microwave Double Injection

Abstract

High-power broadband terahertz dual-comb sources are of great importance for fast high-resolution spectroscopy, but are rare because of the lack of high-performance terahertz radiation sources. Here the authors demonstrate a broadband terahertz dual-comb source on a chip, based on electrically pumped quantum cascade lasers and microwave double injection. By injection locking the two lasers at slightly different round-trip frequencies, even weak microwave power can significantly broaden the dual-comb bandwidth. Furthermore, the double-injection technique allows direct evaluation of the carrier offset noise of the terahertz laser combs.