Nanoscale shaping and focusing of visible light in planar metal–oxide–silicon waveguides

A. David, B. Gjonaj, Y. Blau, S. Dolev, and G. Bartal

Optica Vol. 2, Issue 12, pp. 1045-1048 (2015)
Focusing light at the nanoscale has become a key factor in super-resolution applications. Dynamic control of this focusing can open new avenues in nanoelectronics and bioimaging, but it requires a platform that merges electronics with super-resolution capabilities. We present a planar metal–oxide–silicon (MOS) platform that allows us to shape, tune, and focus visible light at the nanoscale by compressing the wavelength of light fourfold, resulting in a scaled diffraction limit of 65 nm. We exemplify the control and flexibility by demonstrating nanovortex beams and short-wavelength super-oscillations of light that further enhance resolution toward 35 nm. Our platform achieves focusing strength similar to nanoantennas but without structural hotspots; hence it is possible to scan the focus via optical wavefront-shaping techniques. Super-resolution scanning without mechanical translations in a MOS platform can provide a building block for bioimaging, nanolithography, and lab-on-a-chip applications.