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

Abstract

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�נ105�ps/km�?m) and dips to a minima (~?1.60�נ105�ps/km�?m), 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 supermodes 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. � 2014, Springer-Verlag Berlin Heidelberg.