Frontiers of Bright CEP‐Stable Broadband Infrared Sources

ABSTRACT Carrier‐envelope phase (CEP)‐stable ultrashort pulse sources in the short‐wave infrared (SWIR) and mid‐infrared (MWIR) are central to modern ultrafast laser science. By combining robust CEP control with high average power and near‐single‐cycle pulse durations, these sources provide compact and versatile platforms for applications ranging from high‐resolution ultrafast spectroscopy and coherent imaging to strong‐field physics. This review surveys recent advances that are driving the broader adoption of coherent broadband few‐cycle infrared ultrafast systems, and we discuss frequency down‐conversion schemes based on difference‐frequency generation and intra‐pulse difference‐frequency generation, optical parametric generation and amplification, passive CEP‐stable architectures, and coherent multi‐octave infrared sources. Such ultrafast CEP‐stable sources provide unprecedented control over spectral tunability, phase stability, and pulse characteristics, fostering exciting opportunities across spectroscopy, imaging, and attosecond science.