Focusing Electromagnetic Fields with Cascaded Circular Apertures

Diffraction from apertures – often understood as a detrimental effect that makes the beam size larger – can be used to focus light in proper configurations. Following the theory of M. De, et al., Appl. Opt. 7, 483-488 (1968), and J. W. Y. Lit, et al., J. Opt. Soc. Am. 59, 559-567 (1969), we demonstrate such effects in VirtualLab Fusion with its flexible Fourier transform settings. In the following two examples, we show the field along z axis, analyze it on the focal plane, and compare it with the reference.