Design and optimization of tapered structure of near‐field fibre probe based on finite‐difference time‐domain simulation
The finite‐difference time‐domain method was employed to simulate light propagation in tapered near‐field fibre probes with small metal aperture. By conducting large‐volume simulations, including tapered metal‐cladding waveguide and connected optical fibre waveguide, we illustrated the coupling between these guiding modes as well as the electric field distribution in the vicinity of the aperture. The high collection efficiency of a double‐tapered probe was reproduced and was ascribed to the shortening of the cut‐off region and the efficient coupling to the guiding mode of the optical fibre. The dependence of the efficiency on the tapered structure parameters was also examined.
Propagation of uncertainties and applications in numerical modeling: tutorial.
Some inputs of computational models are commonly retrieved from external sources (handbooks, articles, dedicated measurements), and therefore are subject to uncertainties. The known experimental dispersion of the inputs can be propagated through the numerical models to produce samples of outputs. The stemming propagation of uncertainties is already significant in metrology but also has applications in optimization and inverse problem resolution of the modeled physical system. Moreover, the information on uncertainties can be used to characterize and compare models, and to deduce behavior laws. This tutorial gives tools and applications of the propagation of experimental uncertainties through models. To illustrate the method and its applications, we propose to investigate the scattering of light by gold nanoparticles, which also enables the comparison of the full Mie theory and the dipole approximation. The position of the localized surface plasmon resonance and the corresponding value of the scattering efficiency are more specifically studied.
Exciton transport into a single GaAs quantum wire studied by picosecond near-field optical spectroscopy
We report a time-resolved near-field luminescence study of excitonic real-space transfer into single GaAs quantum wires. Excitons generated by local optical excitation in a 250 nm spot undergo diffusive transport over a length of several microns and are subsequently trapped into the quantum wire by optical phonon emission. Local energy barriers in the vicinity of the quantum wire, originating from the epitaxial growth mechanism of the nanostructure, directly influence the real-space transfer dynamics and trapping efficiency.