Zongfu Yu（喻宗夫）
Department of Electrical and Computer Engineering
University of Wisconsin - Madison
时 间：2014年5月16日 (星期五) 下午2:00-5:00
地 点：唐仲英楼 B501
摘要: The control of thermal radiation is of great current importance for applications such as energy conversions and radiative cooling. Here Dr.Yu shows theoretically that the thermal emission of a finite-size blackbody emitter can be enhanced in a thermal extraction scheme, where one places the emitter in optical contact with an extraction device consisting of a transparent object, as long as both the emitter and the extraction device have an internal density of state higher than vacuum, and the extraction device has an area larger than the emitter and moreover has a geometry that enables light extraction.
The second part of the talk focuses on superradiant thermal emission. The superradiant state reduces the lifetime of a collection of excited atom, which leads to enhanced spontaneous emission that scales as N2 with the number of emitters N. Superradiant emission will be discussed for thermal emitters consisting of optical nanoresonators. In contrast to excited quantum emitters, the superradiant state decreases the emission power from thermal emitters, by a factor as much as 1/N. The suppressed emission is caused by the reduced lifetime of nanoresonators as a result of the superradiant in-phase oscillation of thermal emitters. .