Fig. 2: Focusing of PhPs using patterned subwavelength cavities.

a AFM topography of the Au edge with the resonators of triangular shapes. The hBN flake thickness is 45 nm. Magenta dashed line shows the edge between Au and SiO2. b Experimental s-SNOM amplitude (S3) map vs. the tip position recorded at ω = 1450 cm−1. Orange dashed lines indicate the edges of the cavity-launched resonator modes. c s-SNOM amplitude (S3) profiles taken across cavity-lanched waves (magenta, blue, and black lines) and the hBN flake edge on Au (purple line). Dashed lines show exponential decay fit for each curve.