Spatial and spectral mode mapping of a dielectric nanodot by broadband interferometric homodyne scanning near-field spectroscopy

Abstract

We investigate the optical properties of nanostructures of antimony sulfide (Sb 2 S 3), a direct-bandgap semiconductor material that has recently sparked considerable interest as a thin film solar cell absorber. Fabrication from a nanoparticle ink solution and two-and three-dimensional nanostructuring with pattern sizes down to 50 nm have recently been demonstrated. Insight into the yet unknown nanoscopic optical properties of these nanostructures is highly desired for their future applications in nanophotonics. We implement a spectrally broadband scattering-type near-field optical spectroscopy technique to study individual Sb 2 S 3 nanodots with a 20-nm spatial resolution, covering the range from 700 to 900 nm. We show that in this below-bandgap range, the Sb 2 S 3 nanostructures act as high-refractive-index, low-loss waveguides with mode profiles close to those of idealized cylindrical waveguides, despite a considerable structural disorder. In combination with their high above-bandgap absorption, this makes them promising candidates for applications as dielectric metamaterials, specifically for ultrafast photoswitching.

Super‐Resolved Bulk States of Photonic Crystals With Cathodoluminescence Microscopy

“…The conventional approach to characterize the spatial profile of r-LDOS is scanning near-field optical microscopy (SNOM), by which the LDOS landscape can be measured with the scanning nanoscale probe. [22][23][24][25][26] However, the recorded LDOS is inevitably perturbed by the scanning probe, and the squeezed detection volume results in a huge decrease in the signal intensity. Recently, the electron beam as a noninvasive virtual dipole source was also utilized for LDOS detection, constituting a suitable tool for the nanometric characterization of photonic nanostructures.…”