An official website of the United States government
Using transdimensional plasmonic materials (TDPM) within the framework of fluctuational electrodynamics, we demonstrate nonlocality in dielectric response alters near-field heat transfer at gap sizes on the order of hundreds of nanometers. Our theoretical study reveals that, opposite to the local model prediction, propagating waves can transport energy through the TDPM. However, energy transport by polaritons at shorter separations is reduced due to the metallic response of TDPM stronger than that predicted by the local model. Our experiments conducted for a configuration with a silica sphere and a doped silicon plate coated with an ultrathin layer of platinum as the TDPM show good agreement with the nonlocal near-field radiation theory. Our experimental work in conjunction with the nonlocal theory has important implications in thermophotovoltaic energy conversion, thermal management applications with metal coatings, and quantum-optical structures.
more »
« less
Far‐ and Near‐Field Heat Transfer in Transdimensional Plasmonic Film Systems
Abstract A confinement‐induced nonlocal electromagnetic response model is applied to study radiative heat transfer processes in transdimensional plasmonic film systems. The results are compared to the standard local Drude model routinely used in plasmonics. The former predicts greater Woltersdorff length in the far‐field and larger film thicknesses at which heat transfer is dominated by surface plasmons in the near‐field, than the latter. The analysis performed suggests that the theoretical treatment and experimental data interpretation for thin and ultrathin metallic film systems must incorporate the confinement‐induced nonlocal effect in order to provide reliable results in radiative heat transfer studies. The fact that the enhanced far‐ and near‐field radiative heat transfer occurs for much thicker films than the standard Drude model predicts is crucial for thermal management applications with thin and ultrathin metallic films and coatings.
more »
« less
- Award ID(s):
- 1830874
- PAR ID:
- 10403053
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Optical Materials
- Volume:
- 11
- Issue:
- 10
- ISSN:
- 2195-1071
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
We use quantum electrodynamics and the confinement-induced nonlocal dielectric response model based on the Keldysh-Rytova electron interaction potential to study the epsilon-near-zero modes of metallic films in the transdimensional regime. Peculiar effects are revealed such as the plasmon mode degeneracy lifting and the dipole emitter coupling to the split epsilon-near-zero modes, leading to thickness-controlled spontaneous decay with rates increased by up to three orders of magnitude.more » « less
-
Heat exchange between a solid material and the gas environment is critical for the heat dissipation of miniature electronic devices. In this aspect, existing experimental studies focus on non-porous structures such as solid thin films, nanotubes, and wires. In this work, the proposed two-layer model for the heat transfer coefficient (HTC) between a solid sample and the surrounding air is extended to 70-nm-thick nanoporous Si thin films that are patterned with periodic rectangular nanopores having feature sizes of 100–400 nm. The HTC values are extracted using the 3[Formula: see text] method based on AC self-heating of a suspended sample with better accuracy than steady-state measurements in some studies. The dominance of air conduction in the measured HTCs is confirmed by comparing measurements with varied sample orientations. The two-layer model, developed for nanotubes, is still found to be accurate when the nanoporous film is simply treated as a solid film in the HTC evaluation along with the radiative mean beam length as the characteristic length of the nanoporous film. This finding indicates the potential of increasing HTC by introducing ultra-fine nanoporous patterns, as guided by the two-layer model.more » « less
-
We show that the optical response of ultrathin metallic films of finite lateral size and thickness can feature peculiar magneto-optical effects resulting from the spatial confinement of the electron motion. In particular, the frequency dependence of the magnetic permeability of the film exhibits a sharp resonance structure shifting to the red as the film aspect ratio increases. The films can also be negatively refractive in the IR frequency range under proper tuning. We show that these magneto-optical properties can be controlled by adjusting the film chemical composition, plasmonic material quality, the aspect ratio, and the surroundings of the film.more » « less
-
Abstract Nanostructures made of metallic materials support collective oscillations of their conduction electrons, commonly known as surface plasmons. These modes, whose characteristics are determined by the material and morphology of the nanostructure, couple strongly to light and confine it into subwavelength volumes. Of particular interest are metallic nanostructures for which the size along one dimension approaches the nanometer or even the subnanometer scale, since such morphologies can lead to stronger light–matter interactions and higher degrees of confinement than regular three‐dimensional nanostructures. Here, the plasmonic response of metallic nanodisks of varying thicknesses and aspect ratios is investigated under far‐ and near‐field excitation conditions. It is found that, for far‐field excitation, the strength of the plasmonic response of the nanodisk increases with its thickness, as expected from the increase in the number of conduction electrons in the system. However, for near‐field excitation, the plasmonic response becomes stronger as the thickness of the nanodisk is reduced. This behavior is attributed to the higher efficiency with which a near‐field source couples to the plasmons supported by thinner nanodisks. The results of this work advance the understanding of the plasmonic response of thin metallic nanostructures, thus increasing their potential for the development of novel applications.more » « less
