Terahertz (THz) quantum-cascade lasers (QCLs) are an emerging semiconductor source of compact, high-power THz radiation. Though first realized more than 15 year

The invention of optical frequency combs generated by mode-locked lasers revolutionized time and frequency metrology in the late 1990s. This concept has been ex

A state-of-the-art overview of this rapidly expanding field, featuring fundamental theory, practical applications, and real-life examples.