Spatial dispersion in three-dimensional drawn magnetic metamaterials

Abstract

Abstract:We characterize spatial dispersion in longitudinally invariant drawn metamaterials with a magnetic response at terahertz frequencies, whereby a change in the angle of the incident field produces a shift in the resonant frequency. We present a simple analytical model to predict this shift. We also demonstrate that the spatial dispersion is eliminated by breaking the longitudinal invariance using laser ablation. The experimental results are in agreement with numerical simulations.

Hollow-core waveguides with uniaxial metamaterial cladding: modal equations and guidance conditions

“…We will also assume the MTM's response to be local, and thus not spatially dispersive. While it is well known that in particular in the fiber geometry MTM tend to be spatially dispersive [33,34], it is also well known how such dispersion can be mitigated [34,35]. In this work, first we derive the characteristic equation for guided modes and the relevant mode existence conditions in Section 2.…”

Drawn metamaterials

“…We have shown that at non-normal incidence, the resonant frequency shifts, a consequence of spatial dispersion due to the longitudinal invariance of the fibres, and meaning that effective properties are angle dependent [13]. Spatial dispersion is unavoidable in longitudinally invariant structures, but can be removed by breaking the latter through longitudinal patterning, and can also be used to add tuneability to metamaterial devices [13]. Several magnetic resonators can be drawn within the same fibre [10], which opens up the possibility of creating complex metamaterial structures with a gradient of permittivity, or combined electric and magnetic confinement of THz radiation in flexible metamaterial clad fibres [17].…”

“…The resonant vacuum wavelength is 14 times larger than the resonator diameter. We have shown that at non-normal incidence, the resonant frequency shifts, a consequence of spatial dispersion due to the longitudinal invariance of the fibres, and meaning that effective properties are angle dependent [13]. Spatial dispersion is unavoidable in longitudinally invariant structures, but can be removed by breaking the latter through longitudinal patterning, and can also be used to add tuneability to metamaterial devices [13].…”

“…We have also demonstrated the fabrication of single and double split ring resonators, with magnetic resonances at THz frequencies [10][11][12]. We discuss the limitations of the fabrication process, and the spatial dispersion that is a consequence of the fibre's longitudinal invariance [13]. We discuss avenues for overcoming these perceived limitations, and potential applications.…”

Fiber-Drawn Metamaterial for THz Waveguiding and Imaging

“…An alternative approach to realizing metamaterials with a magnetic response which makes use of fiber drawing but does not make use of the Taylor wire process is to sputter a spool of fully dielectric rods/fibers with metal and obtain ridge u-shaped metal structures [32,33].…”