Slabs with a gap efficiently guide terahertz waves

Thin metal wires can guide terahertz waves with low loss and low groupvelocity dispersion (see "Simulation matches experiment for wire waveguide," p. 24).1 The effect is the same as the so-called Sommerfeld wave known to occur for microwave radiation propagating on metal wires of finite conductivity.2 One disadvantage of Sommerfeld wires is the far-reaching radial extension of the electrical field; on the other hand, with their favorable propagation properties, these wires set a standard for terahertz waveguiding.