Universal features of coherent photonic thermal conductance in multilayer photonic band gap structures

We show that at the high-temperature limit, the coherent photonic thermal conductance of a multilayer photonic crystal can be significantly below the corresponding thermal conductance of vacuum. Moreover, the thermal conductance at this limit is independent of the thicknesses of the layers but dependent on the refractive indices of the layers only. Such universal features are directly related to the ergodic nature of the distribution of photonic bands in the frequency space.