Multiple intersection properties of optical resonance modes in metallic metamaterials

Abstract

Unusual behavior of Fabry-Perot-like waveguide resonance modes is presented for a quasi-dielectric metamaterial that consists of two metallic sub-wavelength cut-through slit-array slabs separated by an air-gap region. Simulations based on the finite-difference time-domain method were conducted. The unique optical properties were interpreted in terms of multiple intersection of the resonance modes. Depending on the intersection conditions of the optical modes, furthermore, a variety of crossing characteristics, i.e., fade-out crossing with/without an isolated loop, anticrossing with/without intensity reduction, and anticrossing with/without frequency repulsion, were identified for the air-gap dependence of the transmission spectra. These findings, which were obtained by careful observation of the properties of this type of metamaterial, present a novel and interesting aspect of the behavior of the optical resonance modes.

Marked effects of lateral displacement on the optical transmission properties of stacked artificial dielectric systems composed of metallic sub-wavelength slit arrays

“…2(d)] exhibits a strange loop-like feature. Based on previous work, 25) this abnormal characteristic can be explained as a result of overshooting of the D 8 mode in the vicinity of s = 0, followed by recombination with the D 7 and D 8 modes at s ≈ 175 μm, which reinstates the normal mode alignment.…”

“…The part below the f c value, therefore, may be assumed to represent the overshooting D 8 mode, which severs the D 7 mode at s of as small as 3 μm as a result of intersection. 25) Here, the situation at l = 60 μm may be considered to represent a transition state, at which point the even-order mode gradually transitions from D 6 H to D 8 . This hypothesis is supported by the observation that the resonance peak curve shape near s = 0 changes from upward convex at l = 50 μm to downward convex at l = 70 μm.…”

“…[14][15][16][17][18][19][20][21] Here, it should be noted that, even below the diffraction limit frequencies, the fundamental optical properties of the artificial dielectric multi-layered structures are not always equivalent to those of conventional dielectric multilayered structures. [22][23][24][25][26] Therefore, it is vital to clarify the basic physical mechanisms underpinning the resonance mode behavior and to determine the exact manner in which the optical characteristics are varied by changing the geometric parameters. In particular, the relative lateral displacement between the slit-array plates, which is a specific structural parameter in laterally periodic systems, may have a significant effect on the resonance mode behaviors.…”

“…Previously, we have examined the optical properties of unshifted and halfpitch-shifted stacked structures, both theoretically and experimentally. 20,[24][25][26] However, the optical characteristics associated with arbitrary intermediate displacements between unshifted and half-pitch-shifted configurations have not yet been systematically examined. In the present work, we therefore performed a detailed theoretical investigation of the effects of the relative lateral displacement on optical transmission properties.…”