Treating  Heat  as  Waves  in  Photonic  Nanostructures     Wah Tung Lau (University of Toronto, Canada, Postdoctoral fellow with Professor Sajeev John)     Collaborators   * Professor Shanhui Fan (Stanford University, USA) * Professor Jung-Tsung Shen (Washington University in St. Louis, USA) * Professor Georgios Veronis (Louisiana State University, USA)     Abstract   Thermal transport is typically an incoherent process. However, for nanostructures with feature sizes smaller than the mean free paths of thermal carriers, thermal transport becomes coherent. Many thermal characteristics are enhanced in the coherent transport regime, since thermal transfer is determined by various wave mechanisms that are unattainable in the conventional incoherent process.   In particular, coherent transport is readily realizable when photon is the main thermal carrier, because of its weak nonlinearity and interactions. In this talk, we will see how photonic band gaps arising from multilayer photonic crystals can be exploited to suppress thermal conductance below that of vacuum, thus enabling extreme thermal insulation [1]. We will further identify the universal limit of such conductance suppression, and its theoretical implications in relation to the statistical features of photonic bands distribution in frequency domain [2].   Lastly, we will address the issue of thermal emission, specifically, the role of guided wave resonances in enhancing near-field spatial coherence of emitted thermal fields, and the potential in realizing thermal antennas [3].     Related Publications   http://www.physics.utoronto.ca/~wlau/publications.html   [1] Tuning Coherent Radiative Thermal Conductance in Multilayer Photonic Crystals W. T. Lau, J. -T. Shen, G. Veronis, S. Fan, and P.V. Braun, Applied Physics Letters 92 103106 (pdf / a brief introduction), (2008).   [2] Universal Features of Coherent Photonic Thermal Conductance in Multi-layer Photonic Crystals W. T. Lau, J. -T. Shen, and S. Fan, Physical Review B80 155135 (pdf) (2009).   [3] Spatial Coherence of the Thermal Electromagnetic Fields in the Vicinity of a Dielectric Slab W. T. Lau, J. -T. Shen, G. Veronis, and S. Fan, Physical Review E76 016601 (pdf), (2007).     Media Coverage   "Photonic Thermos", Physical Review Focus on October 9, 2009. Physical Review B Editors' Suggestions in October 2009 "Scientists Create Material More Insulating than the Vacuum", Physorg.com on December 10, 2009.     Speaker Biography   Wah Tung Lau is a postdoctoral fellow in the Department of Physics, University of Toronto, Canada, with Prof. Sajeev John. His research focuses on theoretical and computational nanophotonics, with emphasis on photonic thermal phenomena and quantum optics. He obtained his PhD in the Department of Electrical Engineering, Stanford University, USA, under the guidance of Professor Shanhui Fan. He received his BENG degree in the Department of Electrical and Electronic Engineering, the University of Hong Kong, before going to Stanford University, where he had also attained a MS degree in Electrical Engineering, and a PhD minor degree in Physics.