Low-Loss Plasmonic Dielectric Nanoresonators

Abstract

Material losses in metals are a central bottleneck in plasmonics for many applications. Here we propose and theoretically demonstrate that metal losses can be successfully mitigated with dielectric particles on metallic films, giving rise to hybrid dielectric-metal resonances. In the far field, they yield strong and efficient scattering, beyond even the theoretical limits of all-metal and all-dielectric structures. In the near field, they offer high Purcell factor (>5000), high quantum efficiency (>90%), and highly directional emission at visible and infrared wavelengths. Their quality factors can be readily tailored from plasmonic-like (∼10) to dielectric-like (∼10), with wide control over the individual resonant coupling to photon, plasmon, and dissipative channels. Compared with conventional plasmonic nanostructures, such resonances show robustness against detrimental nonlocal effects and provide higher field enhancement at extreme nanoscopic sizes and spacings. These hybrid resonances equip plasmonics with high efficiency, which has been the predominant goal since the field's inception.

Low‐Loss Hybrid High‐Index Dielectric Particles on a Mirror for Extreme Light Confinement

“…These results agree with numerical simulations, shown in Figure c, when each nanoparticle is covered by a 3 nm thin SiO 2 native oxide layer (see Figure S2 in the Supporting Information for the oxide thickness dependency). The slight overestimation in the simulation for the peak shift for small spacing s can likely be attributed to nonlocal effects, which start playing a role for gap distances smaller than 5 nm …”

“…The large Ohmic losses also pose a serious limit to the radiative Purcell enhancement of photon emitters coupled to the cavity as the nonradiative relaxation path of the electromagnetic excitation takes place at short timescales. To reduce these parasitic absorptions, it has recently been proposed to create PoM systems with high‐index dielectric nanoparticles as opposed to plasmonic nanoparticles …”

“…To reduce these parasitic absorptions, it has recently been proposed to create PoM systems with high-index dielectric nanoparticles as opposed to plasmonic nanoparticles. [32] High-index dielectric (HID) nanophotonics is rapidly becoming a mature field and may supplant plasmonics in specific applications due to reduced Ohmic losses and CMOS (complementary metal-oxide-semiconductor) compatibility. [33][34][35][36][37] Dielectric nanostructures support multiple Mie resonances of both electric and magnetic character enabling efficient coupling to far-field radiation.…”

Brightening and Guiding Single‐Photon Emission by Plasmonic Waveguide–Slit Structures on a Metallic Substrate

“…The reason will be given in the following. When the nanoslit width is smaller than 5 nm, the quantum corrections cannot be ignored owing to the nonlocality, spill‐out, and surface‐enabled damping . So, we only investigate the situation when the nanoslit width is greater than 5 nm, which is similar to that in the previous works …”

“…When the nanoslit width is smaller than 5 nm, the quantum corrections cannot be ignored owing to the nonlocality, spill-out, and surfaceenabled damping. [46] So, we only investigate the situation when the nanoslit width is greater than 5 nm, which is similar to that in the previous works. [21,46] First of all, the Purcell factors varying with the radius of the sliver nanowire for different nanoslit widths are simulated, and the results are displayed by the black lines in Figure 3a-c. Here, the quantum emitter is placed at (0, y = 5 nm, 0).…”