Sub-50 nm focusing of 405 nm laser by hemispherical silicon nanolens

TL;DR

This paper theoretically demonstrates that a silicon hemispherical nanolens can focus 405 nm light into a spot smaller than 50 nm, offering a low-cost alternative for super-resolution applications.

Contribution

The study provides a theoretical analysis showing sub-50 nm focusing of 405 nm light using silicon nanolenses, highlighting their potential for super-resolution techniques.

Findings

Focus spot width of 42 nm at 405 nm wavelength

Focus depth of 20 nm achieved

High refractive index and small size enable nano-focusing

Abstract

In this work, we study the light focusing behaviors of sub-micron Si hemispherical nanolens in theory. Results show that the width and depth of the focus spot light at 405 nm can reach 42 nm (approximately {\lambda}/10) and 20 nm ({\lambda}/20), respectively. Theoretical analysis indicates that this nano-focusing phenomenon comes from two reasons, the high refractive index of Si and the sub-micro size of the lens which considerably decrease the influence of material losses. The focusing capability of Si nanolens is comparable with current EUV technique but with a low cost, providing an alternative approach towards super-resolution photolithography and optical microscopy.