Prof. Jacob B. Khurgin
Johns Hopkins University, USA
地点：唐仲英楼 B501
时间：2018-11-08 10:00
Recent years have seen staggering growth of interest in using nanoscale metal/dielectric structures in optical and near IR ranges with the goal of enhancing linear and nonlinear optical properties or even engineering novel optical properties unknown in Nature – usually this burgeoning field is referred to as “Plasmonics and Metamaterials”. After the initial years of excitement, the community is slowly beginning to recognize that loss in the metal is an important factor that might impede practical application of plasmonic devices, be it in signal processing, sensing, imaging or more esoteric applications like cloaking. Yet there is still an optimism that the loss can be either cleverly “designed away”, compensated by gain, or a new lossless material can be found. In this talk we examine these concepts one by one and find that they all have limitations. First we show that when it comes to enhancing the device performance (solar cells, sensors etc.) only the most inefficient devices can be improved by plasmonics while the performance of any decent device will only degrade. Then we demonstrate that in truly sub-wavelength metal structures the metal loss is inherent and cannot be engineered away by clever changes in shape. We then consider the idea of compensating loss using semiconductor gain medium and demonstrate that required gain can never be achieved due to increase in recombination rates caused by Purcell effect. Then we turn our attention to New plasmonic materials, such as doped semiconductors or materials with strong phonon resonance have smaller material loss, and using them in place of metals carries a promise of reduced-loss plasmonic and metamaterial structures, with sharper resonances and higher field concentration.
Jacob B. Khurgin had graduated with MS in Optics from the Institute of Fine Mechanics and Optics in St Petersburg, Russia in 1979. In 1980 he had emigrated to US, and, to his own great surprise, immediately landed a job with Philips Laboratories of NV Philips in Briarcliff Manor, NY. There for 8 years he worked with a very modest degree of success on miniature solid-state lasers, II-VI semiconductor lasers, various display and lighting fixtures, X-ray imaging, and small appliances such as electric shavers and coffeemakers (for which he holds 3 patents). Simultaneously he was pursuing his graduate studies at Polytechnic Institute of NY (nowadays NYU School of Engineering) where he had received PhD in Electro-physics in Jan. 1987. In Jan. 1988 Khurgin’ s industrial career rather abruptly came to an end, and he had joined the Electrical and Computer engineering department of Johns Hopkins University, where he had settled down and is currently a Professor. His research topics over the years included an eclectic mixture of optics of semiconductor nanostructures, nonlinear optical devices, lasers, optical communications, microwave photonics, opto-mechanics, and condensed matter physics. Currently he is working in the areas of mid-infrared frequency combs, silicon RF photonics, laser refrigeration, non-reciprocal light propagation and bio-detection. His publications include 8 book chapters, one book edited, 300+ papers in refereed journals and 36 patents. Prof Khurgin had held a position of a Visiting Professor in a number of institutions of relatively high repute– Princeton, UCLA, Brown, Ecole Normale Superieure (Paris), Ecole Polytechnique (Paris), EPFL (Lausanne), ETH (Zurich) and so on. Prof. Khurgin is a Fellow of American Physical Society and Optical Society of America, and loves dogs, skiing, kayaks and bicycles.