Strong-Field 59-mW Terahertz Source Based on High-Repetition-Rate Femtosecond Yb: YAG Laser

Terahertz (THz) sources with electric fields > 100 kV/cm are vital tools for THz nonlinear spectroscopy and THz pump detection technology [1]. In recent years, the output power of the ytterbium (Yb) laser has reached>100 W level, and their pulse energy could arrive at mJ-level, which makes them a good choice for the high-power strong-field terahertz source. Recently, Vogel et al. [2] demonstrated 643 mW THz average power using an expensive 500 W ultrafast thin-disk Yb amplifier. Guiramand et al. [3] produced a 74 mW THz average power with an efficiency of 1.3% by a 280-fs Yb laser with a pulse energy of 0.4 mJ and a repetition rate of 25 kHz. Here, in order to produce a strong-field high-average-power THz output under a favorable cost, we use an industrial 1030 nm Yb: YAG laser with a pulse duration of ~570 fs, a repetition rate of 50 kHz, and a pulse energy of ~ 1 mJ to excite lithium niobate (LN) crystal to generate THz pulses.