High-power intracavity single-cycle THz pulse generation at 44.8 MHz using thin plates of lithium niobate

Dr. Yicheng Wang1, Mr. Mohsen khalili1, Mr. Tim Vogel1, Dr. Samira Mansourzadeh2, Dr. Kore Hasse3, Dr. Sergiy Suntsov3, Prof. Detlef Kip3, Prof. Clara J. Saraceno1
1Photonics and Ultrafast Laser Science (PULS), Ruhr-Universität Bochum, Bochum, Germany. 2Photonics and Ultrafast Laser Science (PULS), Ruhr-Universität Bochum, Bochum, Gibraltar. 3Experimental Physics and Material Sciences, Helmut-Schmidt-Universität, Hamburg, Germany


Resonant enhancement both in passive and active resonators is a well-known technique for boosting the efficiency of nonlinear frequency conversion at high repetition rates. However, this route has remained poorly explored for the generation of few-cycle broadband THz transients due to the inadequacy of typically employed nonlinear crystals. Here, we demonstrate that thin lithium niobate crystals are a promising candidate to circumvent current difficulties. Using a 50-µm thin lithium niobate plate intracavity of a compact high-power mode-locked thin-disk laser, we generate broadband THz pulses with a spectrum extending up to 3 THz at 44.8 MHz repetition rate, driven by 264 W of intracavity average power. This approach opens the door to efficient high-power single-cycle THz generation at high repetition rates, scalable to kilowatt-level driving power with low cost and complexity.