Ultrafast switch-off of metamaterial polariton modes in a terahertz photonic crystal cavity

We investigate the non-adiabatic switching dynamics of a bosonic ultrastrong coupling system consisting of a meta-material in a 1D photonic crystal, and report sub-cycle optical control of the coupling between the plasmons and the cavity photons. By switching-off the plasmon mode by a femtosecond laser pulse, we observe ultrafast changes of the coupled system which strongly depend on the arrival time of the laser pulse.