High-Power Narrowband THz Generation

Narrowband terahertz (THz) pulses can be generated with chirp-and-delay techniques that modulate the optical pulse sent into a THz generation crystal [1]–[3]. The beam is linearly chirped, split, and recombined to interfere with a time-delay such that there is a single frequency present in the multiple oscillations of the modulated pulse. The frequency of the oscillations can be controlled by varying the delay between the two pulses and the chirp. Optical rectification of these modulated pulses generates narrowband THz, whose frequency is tunable with the time delay and the chirp. We propose a simple setup that generates narrowband, high-power THz from 0.1 to 5 THz using the output of an 800 nm Ti:Sapphire laser to pump the organic NLO crystal BNA. To enable the generation of the highest intensity THz pulses, we bond the BNA to sapphire; the high thermal conductivity of the sapphire raises the damage threshold of the crystal so that we can expose it to fluences of up to ~ 15 mJ cm ⁻² [4].