Fig. 1: Naturally canalized phonon polaritons (PhPs) in a thin dielectric layer.
From: Observation of naturally canalized phonon polaritons in LiV2O5 thin layers
a Norm of the electromagnetic field \(\left|E\right|\) numerically calculated in a layer (thickness \(d=\) 200 nm) with permittivity \({\varepsilon }_{x}={\varepsilon }_{y}=5+0.05i\), and \({\varepsilon }_{z}=-{\!5}+0.05i\). A vertically oriented point dipole is employed as polaritonic excitation source. Clear isotropic propagation of strongly confined PhPs is observed. Inset: real part of the out-of-plane component (\({E}_{z}\)) of the electromagnetic field. b Same as a for a permittivity \({\varepsilon }_{x}=5+5i\), \({\varepsilon }_{y}=5+0.05i\), and \({\varepsilon }_{z}=-{\!5}+0.05i\). Anisotropic (arc-shaped) polariton propagation centered along the y-axis is observed. c Same as a and b for a permittivity \({\varepsilon }_{x}=0.05+5i\), \({\varepsilon }_{y}=5+0.05i\), and \({\varepsilon }_{z}=-{\!5}+0.05i\). Naturally canalized PhPs propagate along the y-axis. d–f Isofrequency curve (IFC) obtained by Fourier transforming (FT) the real-space simulation in (a–c), respectively. The white arrows indicate the energy flux S.
