Active Plasmonic Colloid-to-Film-Coupled Cavities for Tailored Light–Matter Interactions

Abstract

For large-scale fabrication of optical circuits, tailored subwavelength structures are required to modulate the refractive index. Here, we introduce a colloid-to-film-coupled nanocavity whose refractive index can be tailored by various materials, shapes, and cavity volumes. With this colloidal nanocavity setup, the refractive index can be adjusted over a wide visible wavelength range. For many nanophotonic applications, specific values for the extinction coefficient are crucial to achieve optical loss and gain. We employed bottom-up self-assembly techniques to sandwich optically active ternary metal-chalcogenides between a metallic mirror and plasmonic colloids. The spectral overlap between the cavity resonance and the broadband emitter makes it possible to study the tunable radiative properties statistically. For flat cavity geometries of silver nanocubes with sub-10 nm metallic gap, we found a fluorescence enhancement factor beyond 1000 for 100 cavities and a 112 meV Rabi splitting. In addition, we used gold spheres to extend the refractive index range. By this easily scalable colloidal nanocavity setup, gain and loss building blocks are now available, thereby leading to new generation of optical devices.

Mechanotunable Plasmonic Properties of Colloidal Assemblies

“…Mater. Interfaces 2020, 7,1901678 Reproduced with permission. [45] Copyright 2017, American Physical Society.…”

“…Mater. Interfaces 2020, 7,1901678 Figure 3. Preparation of monolayers via interface-mediated assembly.…”

“…Mater. Interfaces 2020, 7,1901678 Figure 6. Capillarity-assisted particle assembly with soft-lithography templates.…”

“…The resulting localized surface plasmon resonance (LSPR) evokes intense colors, which are influenced by the size, shape, material, and dielectric environment of the colloidal particle . The resonant field enhancement and subdiffraction electromagnetic energy confinement has led to a variety of applications such as electrochromic smart windows, enhanced oxidation reactions, highly sensitive Raman scattering, energy transport below the diffraction limit, optically active cavities, and nonlinear optical processes . The use of plasmonic back reflectors in photovoltaic devices is of particular interest because they increase the conversion efficiency of inorganic as well as organic solar cells.…”

“…

enhancement and subdiffraction electromagnetic energy confinement has led to a variety of applications such as electrochromic smart windows, [3] enhanced oxidation reactions, [4] highly sensitive Raman scattering, [5] energy transport below the diffraction limit, [6] optically active cavities, [7] and nonlinear optical processes. [8] The use of plasmonic back reflectors [9] in photovoltaic devices is of particular interest because they increase the conversion efficiency of inorganic [10] as well as organic [11] solar cells.

…”