Selective imaging of terahertz electric field of phonon-polariton in LiNbO$_3$

Abstract

Coherent phonon-polaritons have generated wide interest due to their relevance to nonlinear optics and terahertz (THz)-wave emissions. Therefore, it is important to analyze the THz electric fields of phononpolaritons. However, in the majority of previous measurements, only a single component of the THz electric field was detected. In this study, we demonstrate that pump-probe electro-optical imaging measurements using the Stokes parameters of probe polarization enable the phase-resolved selective detection of THz electric field components that are associated with the phonon-polariton. We experimentally distinguished the mode profiles of ordinary and extraordinary phonon-polaritons. These results have been explained by numerical calculations of Maxwell equations for the THz electric field. The technique of selectively observing the THz electric field components may be useful for designing efficient THz-wave emitters.