Optical tunneling of single-cycle terahertz bandwidth pulses - art. no. 036604

We report time-domain measurements with subpicosecond resolution of optical tunneling of terahertz electromagentic pulses undergoing frustrated total internal reflection. Measurements of the transmitted electromagnetic pulses over a 3 THz bandwidth permits direct determination of frequency-dependent phase and amplitude changes in both the thin and opaque barrier limits in a single measurement. A complex frequency response function describing prop agation through the barrier is developed based upon linear dispersion theor y and the Fresnel coefficients at complex angles in the optical barrier. Ou r measurements are in excellent agreement with this theoretical model acros s the experimentally determined bandwidth; the model makes no assumptions a bout the beam path through the barrier and has no adjustable parameters. Th e theory is shown to satisfy the Kramers-Kronig relations, indicating causa l propagation across the barrier.