Fig. 2
From: Ultra-confined surface phonon polaritons in molecular layers of van der Waals dielectrics
Infrared nano-imaging, dispersion and scaling of MoS2–SiC SPhPs. a–h Near-field images (optical amplitude s3) of 7-layer MoS2 on SiC (e–h) recorded at different laser excitation lines (marked as ω), and corresponding cross-sections (a–d) along cyan dotted lines. Cyan and pink colours refer to MoS2 crystal and the substrate (SiC) areas correspondingly. Cyan curves in images (a–d) serve as eye guide. Insets in images (g, h) show zoomed in fringes on the top right hand side part of MoS2–SiC boundary. Scale bars are 500 nm. i Calculated (solid/dotted curves) and experimental (circles) dispersion for different number of MoS2 layers (labelled on each of the curves). Data corresponding to the same number of layers are marked with the same colour. j Calculated and experimental scaling of the SPhPs wavelength with MoS2 thickness. Data corresponding to the same laser line are marked with the same colour
