100-mW high-average power strong-field terahertz source

High-average-power strong-field terahertz (THz) pulses, generated via optical rectification of hundred-watt average-power ytterbium lasers in a nonlinear crystal, have been used to study extreme physical phenomena and enable various applications. However, this THz generation method suffers from the trade-off where high repetition rates lead to low optical-to-THz energy conversion efficiency, as well as the risk of damaging the crystals under high average pumping power. Here, 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 ytterbium femtosecond laser with a tilted-pulse front pumping configuration. By characterizing two key experimental parameters, the pump spot size and the 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% 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 shows its potential capabilities in high signal-to-noise spectroscopy, imaging, non-destructive testing, and relevant THz applications.