Experimental demonstration of a band-notched line-defect waveguide in a surface-wave photonic crystal

Abstract

We propose and experimentally demonstrate a band-notched line-defect waveguide in a surface-wave photonic crystal, which consists of a straight line-defect waveguide and side-coupled defect cavities. A narrow stop band can be observed in the broadband transmission spectra. We also demonstrate that both the filtering levels and filtering frequencies of the band-notched line-defect waveguide can be adjusted through changing the number and the height of metallic pillars of the side-coupled defect cavities. The band-notch function is based on the idea that the propagating surface modes with the resonance frequencies of the side-coupled defect cavities will be tightly localized around the defect sites, being filtered from the waveguide output. Transmission spectra measurements and direct near-field profile imaging are performed at microwave frequencies to verify our design. These results may enable various band-notched devices applications and provide routes for the realization of surface-wave filters on a single metal surface.