Superluminal terahertz pulses
Klaas Wynne and Dino A. Jaroszynski
In femtosecond terahertz-pulse (T-ray) imaging of metal structures with
dimensions of the order of the wavelength, it is observed that the T rays
propagate faster than the vacuum speed of light. In the case of apertures
this can be understood as a waveguide effect in which superluminal velocities
are expected close to the cutoff frequency. However, the effect is also
observed close to knife edges and in propagation past thin metal
