Room-temperature quantum-cascade lasers with nonlinear optical difference-frequency generation

Abstract

Terahertz frequencies ranging from 0.1 THz to 10 THz have considerable potential for applications in numerous fields, including imaging, spectroscopy, and high-speed communication. However, in this frequency range, many key components for widespread commercialization have not been fully established. Terahertz sources based on difference frequency generation in mid-infrared quantum cascade lasers are currently the only electrically pumped monolithic semiconductor laser sources at room temperature in the THz spectral range. Recently, ultra-broadband comb generation and sub-THz quantum cascade laser sources have been demonstrated. In addition, an imaging experiment using THz sources has been successfully performed for the first time. In this article, we report the recent progress of room temperature quantum cascade laser sources.