Usage of Silicon for Label-Free Super-Resolved Imaging

In this chapter, we present a summary of research that uses silicon to enhance the imaging resolution and to push it toward the region of nanoscopy. The silicon has a nonlinear effect called the plasma dispersion effect (PDE), which can be used instead of the fluorescent dye in order to realize a stimulated emission depletion (STED) like microscopic imaging configuration. The silicon can be encapsulated into nanoparticles while the encapsulation may be biocompatible and yield the first step toward label-free bioimaging. The encapsulation may even be metallic to enhance the obtainable effect and to yield resolution enhancement at lower requirements from the pump beam. The silicon can even be used directly as a wafer but then the super-resolving imaging is mainly aimed at failure analysis of micro-electronic circuitry. When the silicon is encapsulated with metallic layer or when it is in the form of a wafer, while being illuminated with a pump beam (in visible wavelength being absorbed by the silicon) it modifies the imaging point spread function (PSF) of the probe beam (a near infra-red wavelength) into a doughnut-like shape, through the utilization of the PDE. This modified PSF has spatial components smaller than the diffraction limit, and by scanning the sample with it, super resolution can be achieved.