报告题目：点亮世界：两条直线和三个箭头创造的奇迹
报告人姓名：Bahram Nabet, Prof.PhD

报告人简介(中文)：德雷塞尔大学教授
报告时间：2016-03-24 14:00
报告地点：校本部东区材料科学与工程学院B楼520会议室
报告内容简介：The incandescent light bulb changed human history since it allowed light to be produced even when the sun had set. It is no surprise that 25% of the world energy goes to lighting. The mechanism of producing this light is not much different from the light produced by our caveman ancestors: heat causes light to radiate. The era of incandescent light ended in the 20th century when visible light was produced by the electronic light emitting diode (LED). As the Nobel Committee noted in the 2014 Nobel Prize: “Incandescent bulb lit the 20th century, the LED will light the 21st.” Our understanding of the emission of light from matter took a great (quantum) leap in 1901 with Planck’s law of black body radiation, but the modern view of both absorption and emission of light from matter is due to the genius of Einstein and dates to ~100 years ago. His elegant picture of two lines and three arrows literally enlightened humanity. The two lines are energy levels; an upward arrow shows absorption of light; a downward arrow (spontaneous) emission of light, and a second downward arrow is light that is stimulated to be emitted by another photon. The downward arrows, and their associated A and B Einstein coefficients, describe the working of LEDs and Lasers, respectively. The LED itself was reported 109 years ago by H. J. Round, an assistant to Marconi. The forgotten inventor of LED, however, is a young genius, Oleg Losev, who observed glow from SiC in 1920’s, published details of experiments in 1929, and even used Einstein’s description of the upward and downward transitions in explaining how this ‘cold’ light emitter works. Losev died of hunger in 1942 during the World War II blockade of Leningrad, at the age of 39. Four research groups in the USA simultaneously reported a functioning LED semiconductor laser based on GaAs in 1962. The invention of the Blue LED is just 20 years old, and, quoting the Nobel Committee “has already started to light our world.” In this seminar I will review the physics of the operation of the LEDs in light of— pun intended— Einstein’s picture, and will describe the LED device operation as well. Time permitting, I will review our work in transition rate management for enhanced light emission and absorption in nanostructures.
报告人简介(英文)：Bahram Nabet received his BSEE from Purdue University, and MS and PhD degrees from the University of Washington, Seattle, WA in 1985, and 1989 respectively. He joined Drexel University, Philadelphia, PA in 1989 and is presently Professor of Electrical and Computer Engineering, and Materials Science and Engineering. His research interests are in low energy computing, and optoelectronics of the interaction light with reduced dimensional systems. He is co-author of nearly 200 publications including 3 books and is a member of the Franklin Institute Committee on Arts and Sciences, established in 1824.