First generation of THz light pulses in high-repetition frequency resonant cavity

A collaborative study between the Department of Physics of the Politecnico di Milano, the Institute of Photonics and Nanotechnology of the CNR, the University of Milan, INFN Milano, Ruhr-Universität Bochum and Helmut-Schmidt-Universität has demonstrated for the first time the generation of single-cycle pulse terahertz radiation by optical rectification in a passive resonant cavity pumped by a commercial ytterbium laser operating at 93 MHz repetition rate.
The experiment exploits a lithium niobate crystal only 50-µm thick and, through the achievement of intracavity powers exceeding 1.9 kW, demonstrates the generation of THz pulses with a bandwidth of about 2 THz and an average power of milliwatt level.
This innovative approach paves the way for new compact, high-efficiency THz sources with applications especially in high-resolution spectroscopy and THz imaging.

The study was published in the journal APL Photonics on April 16, 2025, among the Editor's picks.