Catching a Terahertz Pulse in a Photonic Crystal Net Triggers Dynamic Frequency Conversion

We experimentally demonstrate dynamic frequency conversion of a terahertz (THz) pulse in a waveguide. The mechanism imposes the photonic band structure of a two-dimensional metallic triangular lattice on a THz pulse as it propagates through a silicon-filled parallel plate waveguide (PPWG). By opening up a photonic band gap on an ultrafast time scale, THz photons within the gap are upconverted to higher frequency propagating states.