Johns Hopkins University

Abstract：

Recent years have seen staggering growth of interest in using nanostructured metals in optical range 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, nonlinear switches 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. After that we consider the physics of losses in metals at optical frequencies and show that the nature of these losses is quite different from the losses in RF domain. We then show that negative dielectric constant at optical frequencies does not have to inevitably lead to large absorption, and guardedly point to the tentative way in which new materials with negative dielectric constant and very low loss might be synthesized, thus restoring the hope for Plasmonics and Metamaterials.

Brief CV of Prof. Jacob B Khurgin:

Jacob B. Khurgin graduated with MS in Optics from the Institute of Fine Mechanics and Optics in St Petersburg, Russia in 1979. He then immigrated to the US and began working with Philips Laboratories in New York. For 8 years, he worked on miniature solid-state lasers, II-VI semiconductor lasers, various display and lighting fixtures, X-ray imaging, and small appliances. Simultaneously he pursued his graduate studies at Polytechnic Institute of NY, receiving a PhD in Electro-physics in 1987. In 1988 he joined the Electrical and Computer Engineering Dept. of Johns Hopkins University, where he is currently a Professor. 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 is a Fellow of American Physical Society and The Optical Society.

主持人：陆凌  研究员

联系人：傅琦（82649469）