Fig. 4. Characterization of a device that focuses BSWs 5 µm behind the functional element.

a Simulated and b measured intensity distributions of the BSW around device 1 (see Fig. 3a) that focuses the incident BSW 5 µm behind the element. The inset in b shows the intensity distribution obtained in a high-resolution scan in close proximity to the focal region. c Extracted x-axis line plots of the intensity through the focus. The intensities are normalized