Thermal near-field tuning of silicon Mie nanoparticles

Abstract

Tunable high-refractive-index nanostructures are highly desired for realizing photonic devices with a compact footprint. By harnessing the large thermo-optic effect in silicon, we show reversible and wide thermal tuning of both the far- and near-fields of Mie resonances in isolated silicon nanospheres in the visible range. We perform in situ heating in a transmission electron microscope and electron energy-loss spectroscopy to show that the Mie resonances exhibit large spectral shifts upon heating. We leverage the spectral shifts to demonstrate near-field tuning between different Mie resonances. By combining electron energy-loss spectroscopy with energy-dispersive X-ray analysis, we show a reversible and stable operation of single silicon nanospheres up to a temperature of 1073 K. Our results demonstrate that thermal actuation offers dynamic near-field tuning of Mie resonances, which may open up applications in tunable nonlinear optics, Raman scattering, and light emission.

Designing two-dimensional temperature profiles using tunable thermoplasmonics

“…For larger sizes, the LDOS enhancement can alternatively be achieved through multipolar Mie resonances excited at dielectric and semiconductive microstructures. 1,7,8 Unlike plasmonic nanoparticles, the inner electrical fields in such microstructures are totally nested within their volume. The Mie resonances well contribute to the optical heating provided that radiative and non-radiative (Ohmic) losses are balanced.…”

“…As of today, considerable advances have been achieved towards comprehending the role of enhanced light-matter interaction in generating and controlling heat at the nanoscale. Special attention has been paid to localized surface plasmon resonances (LSPRs) in metallic nanostructures, 2,[4][5][6] multipolar Mie modes in high refractive index dielectric microstructures, 1,7,8 multipolar resonances in epsilon-near-zero (ENZ) media, 9,10 Fano resonances in plasmonic nanostructures, [11][12][13] anapole states in well-designed structures, [14][15][16] and even more exotic electromagnetic excitations, such as topologically protected edge states 17,18 and bound states in the continuum (BIC). 10,19 Also worth mentioning is a nonreciprocal semi-transparent isolator based on the magneto-optical Weyl semimetal EuCd 2 As 2 , recently created by Park et al, 20 which enables full absorption of the incident irradiation with zero backward scattering.…”

Computational Discovery and Experimental Demonstration of Boron Phosphide Ultraviolet Nanoresonators

“…The experimental EELS intensity maps (Figure 4h–j) of these three Mie modes are in good agreement with the simulations as well as previous EELS measurements performed on Mie‐resonant Si nanoparticles. [ 55,56 ]…”

“…The experimental EELS intensity maps (Figure 4h-j) of these three Mie modes are in good agreement with the simulations as well as previous EELS measurements performed on Mie-resonant Si nanoparticles. [55,56] The dark-field scattering measurements (Figure 3) combined with the EELS measurements (Figure 4) show that the optically resonant nature of the BP nanoparticles can be identified both in their far-field and near-field responses, respectively. These resonances are present both in the visible and ultraviolet and their resonance energies can be tuned with particle size.…”

“…To gain more insight into the nature of these resonances and to access the ultraviolet spectral region, we also perform near-field characterization on similar BP nanoparticles using electron energy-loss spectroscopy (EELS). EELS is performed in a transmission electron microscope and has been employed to access near-field properties of both metallic [53,54] and dielectric nanostructures [55][56][57] as well as optical devices. [58] The combined high spatial and spectral resolution of EELS provides unique nanoscale information on optical modes over a broad spectral range.…”