Tuning Coherent Radiative Thermal Conductance in Multilayer Photonic Crystals

TL;DR

This paper demonstrates that multilayer photonic crystals can significantly reduce radiative thermal conductance below vacuum levels across high temperatures by exploiting band gaps and evanescent tunneling suppression, with conductance tunable via layer thickness.

Contribution

It introduces a method to control radiative thermal conductance in multilayer photonic crystals by adjusting layer thicknesses, achieving conductance below vacuum levels.

Findings

Thermal conductance can be below vacuum across high temperatures.

Band gaps and evanescent tunneling suppression are key to conductance reduction.

Conductance is highly tunable by varying vacuum layer thickness.

Abstract

We consider coherent radiative thermal conductance of a multilayer photonic crystal. The crystal consists of alternating layers of lossless dielectric slabs and vacuum, where heat is conducted only through photons. We show that such a structure can have thermal conductance below vacuum over the entire high temperature range, due to the presence of partial band gap in most of the frequency range, as well as the suppression of evanescent tunneling between slabs at higher frequencies. The thermal conductance of this structure is highly tunable by varying the thickness of the vacuum layers.