A photon thermal diode

Abstract

A thermal diode is a two-terminal nonlinear device that rectifies energy carriers (for example, photons, phonons and electrons) in the thermal domain, the heat transfer analogue to the familiar electrical diode. Effective thermal rectifiers could have an impact on diverse applications ranging from heat engines to refrigeration, thermal regulation of buildings and thermal logic. However, experimental demonstrations have lagged far behind theoretical proposals. Here we present the first experimental results for a photon thermal diode. The device is based on asymmetric scattering of ballistic energy carriers by pyramidal reflectors. Recent theoretical work has predicted that this ballistic mechanism also requires a nonlinearity in order to yield asymmetric thermal transport, a requirement of all thermal diodes arising from the second Law of Thermodynamics, and realized here using an ‘inelastic thermal collimator’ element. Experiments confirm both effects: with pyramids and collimator the thermal rectification is 10.9±0.8%, while without the collimator no rectification is detectable (<0.3%).

Evaluating Broader Impacts of Nanoscale Thermal Transport Research

“…Theoretical advances provide hope for much Downloaded by [New York University] at 07: 56 12 June 2015 needed cross-validations between theory and experiment without any free parameters and for problems ranging from thermal phonon coherence to thermal boundary conductance. Nonlinear and actively controlled heat conduction is another opportunity, including thermal diodes and switches [51][52][53][54][55]. Unconventional carrier types such as magnons are also of interest [56][57][58][59][60].…”

Phononic thermal resistance due to a finite periodic array of nano-scatterers

“…It may provide a basis for future investigations dealing also with non-linear mechanisms [48,49] expected to exhibit thermal rectification effects.…”

Thermotronics: Towards Nanocircuits to Manage Radiative Heat Flux

“…An important step forward in this direction has been carried out by Otey et al [12] by introducing the first radiative thermal rectifier by exploiting the thermal dependence of optical properties of materials in interaction. During the next 5 years, the rectification performances have been improved [13][14][15][16][17][18] until the development of a phase-change radiative thermal diode able to rectify 66 % of heat flux in far-field [19,20] and even more than 99 % in the near-field regime [21], respectively. Contrary to the relatively weak dependence with respect to the temperature of optical properties of materials used in the thermal rectifier developed so far, the phasechange thermal diode exploites a sudden change of these properties around a critical temperature, the transition temperature.…”