100-mW High-Average-Power Strong-Field Terahertz Source

High-average-power strong-field terahertz (THz) pulses, which are generated via the optical rectification of 100-W average-power ytterbium (Yb) lasers in a nonlinear crystal, have been used to study extreme physical phenomena and realize various applications. However, this THz generation method suffers from a trade-off in which high repetition rates lead to low optical-to-THz energy conversion efficiency, as well as the risk of damage to the crystals under high average pumping power. In this study, we demonstrate a high-average-power, high-repetition-rate, strong-field THz source in lithium niobate driven by a 1030 nm, 1 ps, 2 mJ, 100 kHz Yb femtosecond laser with a tilted-pulse front-pumping configuration. By characterizing two key experimental parameters, namely the pump spot size and pulse duration, we achieve, to the best of our knowledge, the highest THz average power of 104 mW at 100 kHz, with a conversion efficiency of 0.1% and without any cooling operation at room temperature. In addition, a strong electric field of 421 kV/cm is achieved at 1 kHz. Our THz system directly demonstrates its potential capabilities in high-signal-to-noise spectroscopy, imaging, non-destructive testing, and relevant THz applications.