Figure 2: Fanciful depiction of a polaritonic circuit illustrating fully integrated terahertz wave generation, guidance, manipulation, and readout in a single patterned material. Phonon-polaritons are generated in the upper left and lower right hand corners by focusing femtosecond optical excitation pulses into the crystal near waveguide entrances. Phonon-polaritons propagate laterally away from the excitation region and into the waveguides. Signal processing and circuit functionality is facilitated by resonant cavities, reflectors, focusing elements, coupled waveguides, splitters, combiners, interferometers, and photonic bandgap structures created by milling channels that fully extend throughout the thickness of the crystal.