Optical properties of metallic meanders

A vertical metallic meander structure with a rectangular corrugated surface profile represents a frequency-selective surface in which the excitation and interaction of localized surface plasmon modes are controlled in a flexible fashion by its geometrical parameters over a large spectral range. In this report we investigate the optical properties of metallic meanders numerically. Although the structure is simple from both the structural geometry and the nanofabrication point of view, its plasmonic band structure manifests rich features that would be very attractive for plasmonic functional devices. In particular, the short-range surface plasmon mode can be tuned by changing the meander depth without altering the long-range surface plasmon mode. To obtain deeper physical insight into the relationship between the structural geometry and its optical response, a transmission line equivalent circuit model is used. It is revealed that circuit parameters that were fitted from numerical scattering parameters have physical relationships with the structural parameters, which can be described by quasi-static or radiative descriptions. In certain frequency ranges, enhanced transmission occurs due to the interaction of magnetic and electric dipole resonances. The calculated effective material parameters reveal that enhanced transmission occurs around the near-zero index frequencies. The application potential of these structures as frequency filters is discussed.