Special CPM Seminar

Breaking Kirchhoff's Law of Thermal Radiation and Its Implications in Energy Applications

Bo Zhao

Department of Mechanical Engineering
University of Houston

Objects around us constantly emit and absorb thermal radiation. The basic properties that characterize these two processes are emissivity and absorptivity, respectively. For reciprocal systems, the emissivity and absorptivity for a given direction, polarization, and frequency are tightly restricted to be equal by Kirchhoff's law of thermal radiation. This restriction limits the control of thermal radiation and contributes to an intrinsic loss mechanism in photonic energy harvesting systems. In this talk, I will discuss how one can break Kirchhoff's law by introducing nonreciprocity and the implications of this effort in solar energy harvesting.