Photonic jets for micro-etching

Abstract

Photonic jet is a localized sub-wavelength beam generated at the shadow-side surfaces of microscale dielectric cylinders or spheres, when they are illuminated by an electromagnetic wave. We demonstrate the potential of the photonic jets for micro-etching using a nanosecond Near-IR laser (λ= 1064 nm) that has a typical spatial resolution around 70 μm, limited by its optical focusing head. Combining this laser with micro-scale glass (ns = 1.5) and BaTiO3 spheres (n s = 1.9) to achieve photonic jets, we can etch two substrates: silicon wafers, which have a significant absorption at 1064 nm, and glass plates, which have a lower absorption at this wavelength. The smallest marks achieved on silicon have an average diameter of 1.3 μm which is 50 times smaller than without spheres. Despite the low absorption, micrometric etchings have also been achieved on glass.