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Two Studies: Plasmon-Enhanced Absorption in Silicon Substrate and On the Universal Behavior of Electro-Optical Materials

Speaker: Uzi Efron , Professor/Ben-Gurion University, Negev, Beer-Sheva, Israel.

Talk Title: Two Studies: Plasmon-Enhanced Absorption in Silicon Substrate and On the Universal Behavior of Electro-Optical Materials

Abstract:
1. Computer simulation studies of absorption enhancement in a silicon substrate by nanoshell-related Localized Surface Plasmon Resonance (LSPR) based on a Finite Difference Time Domain (FDTD) analysis will be presented. The results of these studies show significant enhancement of over 4X in the near band gap spectral region of Si, using 30nm diameter, 2-Dimensional,cylindrical Ag nanoshell structure. The studies also indicate a clear advantage of the cylindrical nanoshell structure over that of a completely filled Ag-nano- cylinders. The enhancement was studied as a function of the metallic shell thickness. The results suggest that the main enhancement mechanism in this case of cylindrical nanoshells embedded in Si substrate, is that of field-enhanced absorption caused by the strongly LSPR-enhanced electric field, extending into the silicon substrate.

2. Electro-optical light modulators are key components for a number of optical systems including displays, optical interconnects, optical processing, optical beam steering and adaptive optics . The performance of these modulators can be characterized by three main physical parameters: The electro-optical coefficient, the RF frequency bandwidth and the optical spectral bandwidth. A recent study [1] has shown that the product of these three parameters, which we term ”Susceptibility-Bandwidth Product” (SBP), is remarkably constant within 1-2 orders of magnitude, across a wide range of different material systems, including Liquid Crystals (LC) , Solid State Electro-Optical Materials and Multiple Quantum Well structures. This, despite the fact that all three parameters vary over many orders of magnitude across this range of materials. The feasibility of the SBP constancy based on material stability considerations has already been proposed several years ago [2]. The main purpose of this study was to perform a detailed study of the SBP in Nematic Liquid Crystal (NLC) materials based on the electro-optics of the electrically controlled birefringence effect. The work includes the derivation of a theoretical expression for the SBP in NLC materials, as well as its comparison to experimental data. The results are found to be in good agreement with the theoretical prediction for this product.

References
1. U. Efron, in Handbook of Opto-Electronics, J.P. Dakin and R.G.W.Brown, Editors, Taylor and Francis, London, 2006, Vol. 2.
2. U. Efron “Spatial Light Modulators and Applications for Optical Information Processing”, in “Real Time Signal Processing for Industrial Applications”, Proc. SPIE, vol.960 (1988).


Biography: Uzi Efron (M’87) received the B.Sc., M.Sc., and Ph.D. degrees from Tel Aviv University, Tel Aviv, Israel, in 1967, 1970, and 1976, respectively, all in physics. He was a Principal Scientist at Hughes Research Laboratories, Malibu, CA, where he conducted research on photo-activated and charge-coupled device (CCD)-addressed liquid crystal light valves as well as multiple-quantum-well spatial light modulators and their applications in projection/head-mounted displays, optical data processing, and adaptive optics. He is currently an Associate Professor at the Electro-Optics Engineering Department, Ben-Gurion University, Negev, Beer-Sheva, Israel. He also heads the OPTO-ULSI Laboratory at Holon Academic Institute of Technology, Holon, Israel. He is currently conducting research on liquid crystal devices, plasmonics, CMOS-ultra-large-scale integration (ULSI) technology, and image processing for applications in smart goggle/head-mounted display devices, low-vision aids, face recognition techniques, and beam-steering devices. Dr. Efron is a Fellow of the Optical Society of America.


Host: Prof. B. Keith Jenkins

Location: Hughes Aircraft Electrical Engineering Center (EEB) - 248

Audiences: Everyone Is Invited

Contact: Talyia Veal