Plasmonics: Dazzling Promise, Harsh Reality, and a Glimmer of Hope.
Feb 01, 2013
from 03:00 PM to 04:30 PM
|Where||Engr. IV Bldg., Maxwell Room 57-124|
|Contact Name||Dr. Eric Diebold|
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Jacob B. Khurgin
Johns Hopkins University
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 belatedly 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 materials 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 optical devices, 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 crafty changes in shape. Graphene as an alternative plasmonic material will also be considered and found to fall well short of being a universal cure for plasmonic ills. 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 faint hope for plasmonics.
Jacob B. Khurgin had graduated with MS in Optics from the Institute of Fine Mechanics and Optics in St Petersburg, Russia in 1979, where, naturally, he was had been earlier born. In 1980 he had emigrated to US, and, to his own great surprise, immediately landed what then seemed to be a meaningful job with Philips Laboratories of NV Philips in Briarcliff Manor, NY. There for 8 years he worked with various degrees 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, prompted by a promotion to a Department Manager, Khurgin’s industrial career came to an abrupt end, and he had joined the Electrical and computer engineering department of Johns Hopkins University, where, despite his ever present reservations about that place, 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, and condensed matter physics. Currently he is working in the areas of mid-infrared lasers and detectors, phonon engineering for high frequency transistors, disorder in condensed matter physics, plasmonics, coherent secure optical communications, silicon photonics, cavity optomechanics, and slow light propagation. His publications include 6 book chapters, one book edited, 240 papers in refereed journals and 28 patents. Prof Khurgin had held a position of a Visiting Professor in an array of institutions of variable degrees of repute – Princeton, UCLA, Brown, Ecole Normale Superieure (Paris), Ecole Polytechnique (Paris) and so on. Prof. Khurgin is a Fellow of American Physical Society and Optical Society of America.