Pulse-width dependence of terahertz parametric generation in the sub-picosecond regime

The present study investigated the generation characteristics and phase stability of terahertz parametric generation in the ultrashort pulse regime. The experimental results clearly demonstrated the emergence of parametric gain in LiNbO₃, with the generation threshold appearing at a pulse width of approximately 700 fs, which closely corresponds to the Raman linewidth of the crystal. The generated terahertz waves were found to exhibit high inter-pulse phase stability. These findings indicate that parametric terahertz generation with gain in the sub-picosecond regime can serve as a basis for developing broadband pulsed sources suitable for terahertz time-domain spectroscopy.