Fig. 5: False colour hyperspectral image as in Fig. 3, but with the sample replaced with one assembled with far fewer contaminants between layers.

The resulting much improved VNA transmission spectrum is shown inset. \(\bar{\lambda }\) denotes the wavelength at 15 GHz in free space. The monochromatic images for the full dataset of can be seen in Supplementary Information 1 Fig. S14.