Fig. 1. (a) Schematic of the standard quasi-cavity structure. (b) Interdigitated switch. (c) Enhanced view of the latter. The quasi-cavity structure has a buried metal plane a few micrometers, d, below the surface of the interdigitated structure.

Fig. 2. Electromagnetic simulations of the x polarized emitted electric field at 1 and 1.5 THz (maximum field emission of the standard and quasi-cavity PC switch, respectively) for the (a), (b) quasi-cavity and (c), (d) standard PC switch.

Fig. 3. 2D plot of the simulated electric field as a function frequency (y axis) and GaAs active thickness d (x axis). The black solid line corresponds to the quarter wavelength condition with a refractive index of 3.6.

Fig. 4. Normalized experimental (black) and simulated (red) spectral response of the quasi-cavity structure. Inset shows the measured time trace.

Fig. 5. (a) Time response of electric fields and (b) spectrum of standard and quasi-cavity-based PC switches.

Fig. 6. Average power as a function of the applied field for standard (red) and quasi-cavity (black) PC switch.

Fig. 7. 2D plot of electromagnetic field distribution for the standard structure with (a) 2 μm and (b) 4 μm interdigit spacing.

Fig. 8. (a) Optical image (front) of the object. (b) Optical image (back of object) of hidden text. (c) Real-time image from the THz camera using the high average power from the quasi-cavity PC switch showing the hidden text. A real-time video is shown in Visualization 1.

Fig. 9. Schematic of real-time imaging setup. The PC switch is excited by an 800 nm IR beam passing through a hole in the first parabolic mirror. The object to be imaged is placed just after the second parabolic mirror. IR filters ensure that no IR radiation is incident on the camera.