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

a Simulated and b measured intensity distribution of the BSW around device 2 (see Fig. 3b) that focuses the incident BSW directly 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