Terahertz pulse generation beyond excitation pulse limitation by χ(2) cascaded processes

We propose a novel technique for the generation of high power monocycle terahertz (THz) pulse beyond excitation pulse width limitation. When intense THz electric field generated by optical rectification lies in EO crystal, optical pulse itself gets modulated by emitted THz electric field. It causes excitation pulse compression and consequently gives rise to the enhancement of generation efficiency and its bandwidth. We experimentally demonstrate it using tilted wavefront excitation beam by LiNbO₃ from Yb doped fiber laser.