THz mode-coupling in photonic-crystal-surface-plasmon-coupled waveguides

摘要

We present a detailed design principle and propagation characteristics of a channel plasmon-photonic-crystal-coupled-waveguide (PPCCW) for realizing terahertz (THz) waveguides and waveguide-based devices. The avoided-crossing behavior exhibited by dispersion curves of the supermodes due to modal interference leads to a sharp change in group velocity close to the phase-matching wavelength. As a consequence, the group-velocity dispersion (GVD) peaks to a maxima (～1.40 × 10~5 ps/km-μm) and dips to a minima (～-1.60 × 10~5 ps/km-μm), thus exhibiting extremely large GVD. The propagation length is obtained in the order of a few centimeters. The analysis is substantiated by the frequency dependence of mode field distribution and propagation loss suffered by the super-modes of PPCCW geometry. Also, the obtained result is in good agreement with FEM-based study. The proposed waveguide is aimed at facilitating enhanced performance THz-waveguide sensors and GVD compensation modules.