Radiative heat transfer at the nanoscale

Abstract

International audienceHeat can be exchanged between two surfaces through emission and absorption of thermal radiation. It has been predicted theoretically that for distances smaller than the peak wavelength of the blackbody spectrum, radiative heat transfer can be increased by the contribution of evanescent waves(1-8). This contribution can be viewed as energy tunnelling through the gap between the surfaces. Although these effects have already been observed(9-14), a detailed quantitative comparison between theory and experiments in the nanometre regime is still lacking. Here, we report an experimental setup that allows measurement of conductance for gaps varying between 30 nm and 2.5 mu m. Our measurements pave the way for the design of submicrometre nanoscale heaters that could be used for heat-assisted magnetic recording or heat-assisted lithography

Enhancing far-field thermal emission with thermal extraction

“…We emphasize that our results do not violate the Stefan-Boltzman law, as the physical area of the thermal extraction device is larger than the emitter itself. In this sense our results are fundamentally different from near-field thermal transfer experiments where Stefan-Boltzman law does not apply [20][21][22][23][24][25] . Our finding here is consistent with known physics of radiometry including the consideration of optical etendue conservation 26 .…”

One-dimensional surface phonon polaritons in boron nitride nanotubes

“…S urface phonon polaritons (SPhPs), the infrared (IR) counterparts to surface plasmon polaritons (SPPs), originate from coupling between electromagnetic waves and optical phonons of polar materials [1][2][3][4] . SPhPs and SPPs share similar traits: propagation along a boundary, high field density at the surface, a reduction of the guided wavelength (compared with free space) and spatial coherence of charge oscillations [5][6][7][8][9][10][11][12] .…”

Proximity effects in radiative heat transfer

“…Rousseau et al 3 integrated the radiative heat transfer coefficient h (z) using the proximity approximation form to compute the theoretical conductance between a sphere and a flat surface. Applying the same form of proximity approximation for finding the conductance between two spheres, we get:…”