High-intensity single-pulse extraction using a laser-activated GaAs reflective switch for a terahertz free-electron laser

Abstract

Single-pulse extraction from a terahertz (THz) pulse train is demonstrated for a free-electron laser oscillator using the laser-activated semiconductor switching technique with gallium arsenide (GaAs). Using a GaAs wafer as the switching substrate and a titanium sapphire laser (Ti:sapphire laser), a single THz pulse can be extracted with a high contrast from the pulse train at intervals of 37 ns in a simple experimental setup due to a short decay time of the electron–hole plasma. For a single THz pulse with a duration of a few to a few tens of picoseconds and a nominal wavelength of 70μm, we achieve an extracted single pulse energy of 76 μJ.