Strongly confined plasmonic wave propagation through an ultrawideband staggered double grating waveguide

In the course of research on high power terahertz vacuum electronic radiation sources, it was discovered that an intense plasmonic wave propagates through the channel between a half-period-staggered pair of TE-mode gratings. Experimental measurements were in good agreement with both a theoretical model and simulation analysis within 2% over the passband. This phase-shifted geometric modulation supports a dynamic bandwidth exceeding 25% with signal attenuation of less than 0.15dB∕cm (at Ka-band). Finite-difference time-domain analysis revealed that this low dispersion and low-loss optical response is ascribed to point-contact hopping motion of widespread resonant waveguide modes with the same phase velocity.