Fig. 4: Experimental phonon polaritons and simulated electromagnetic waves in the microcavity.
a Energy bands of the LiNbO3 photonic crystal. The gray region indicates the bandgap spanning from 0.375 to 0.490 THz in the band structure. b Electric field oscillation of a point in the microcavity, and the point is presented by the black dot in the top inset. The top inset also shows the pump position, while the bottom inset indicates the femtosecond laser-generated broadband THz phonon polaritons, the initial oscillation after the first 5 ps from the microcavity confined phonon polaritons. c Spectral information of the microcavity confined phonon polaritons, Fourier transformation of (b). The inset presents the spectral comparison between the broadband and localized phonon polaritons. d Simulated spectral information at the line shown by the inset, in the microcavity. e Spectral information along a line and at a point in the microcavity, where the positions of the line and the point are the same as in the experiment.
