Figure 5. Analysis of the SM0-S mode of a rectangular waveguide of 250 nm width and 65 nm thickness.

(a) Simulated near-field distribution (Re(E_z)) of the SM0-S mode at 1,445 cm⁻¹ (top) and 1,416 cm⁻¹ (bottom). Scale bar, 100 nm (a). (b) Calculated dispersion of the SM0-S mode. The inset shows the schematics of the waveguide and the near-field distribution of the SM0-S mode at 1,445 cm⁻¹. The dashed line indicates the direction of the near-field profiles in c,d. (c) Calculated near-field profile of |E_z| in a height of 5 nm above the waveguide surface of the waveguide at 1,445, 1,432, 1,424, 1,400 and 1,381 cm⁻¹ (from top to bottom) (d) Experimental near-field profiles measured at 1,443, 1,432, 1,424, 1,416 and 1,408 cm⁻¹ (from top to bottom). For better visibility of the near-field variations, we plot the central part of the near-field profiles in b,c in darker colour. For a better comparison of calculated and experimental near-field profiles in c,d, we mark local near-field maxima by black arrows.