Figure 1

Transmission spectra featuring trapped-mode resonances of the coherent (asymmetric split rings, solid red [medium gray] curve, ${\nu }_{\mathrm{coh}}$) and incoherent (concentric rings, solid blue [dark gray] curve, ${\nu }_{\mathrm{inc}}$) metamaterial arrays of 88 metamolecules. Dashed curves indicate transmission stop bands in the absence of trapped-mode excitations. The top right inset shows a sample of 88 metamolecules (unit cells) of the coherent array exposed through a metal mask (represented by the darker area). Other insets show the current modes excited in the unit cells of the coherent (left) and incoherent (right) metamaterials and the corresponding induced magnetic dipole moments $m$.Reuse & Permissions

Figure 2

$Q$-factor as a function of the total number of metamolecules. Experimentally measured data are represented by points for both coherent (diamonds) and incoherent (circles) metamaterials. Solid lines present theoretical fits to the data.Reuse & Permissions

Figure 3

Panel (a) shows the spectral dependence of the squared total magnetic flux amplitude through an ASR for the cases of one isolated ring (empty squares) and a ring located in the middle of a $20\times 20$ array (filled squares). Panels (b) and (c) present snapshots of the instantaneous magnetic field normal to the plane of the ring (color coded) and the in-plane electric field (arrows) at resonance frequencies ${\nu }_1$ and ${\nu }_2$ correspondingly. To show both fields at their maxima on the same map the magnetic and electric fields are presented with a phase shift of $\pi /2$. The inset shows the experimental configuration for the THz near-field scans. A near-field probe is raster scanned behind the sample illuminated by a THz pulse.Reuse & Permissions

Figure 4

(a) Scanning electron microscopy images of coherent metamaterial arrays of different sizes. (b) Schematic of the metamaterial unit cell. (c) Transmission spectra of the metamaterials in the vicinity of the trapped-mode resonance. Inset to (c): spectrum of the $12\times 12$ array over a much wider wavelength range; a dashed box indicates the spectral domain that is covered by the main plot, while an arrow marks the resonance.Reuse & Permissions