Surface plasmons are the quanta of longitudinal oscillations of free electrons at the surface of free electron rich materials, such as metals or doped semiconductors. Based on the dimensions of the metal and the configuration of the structure, various kinds of plasmonic excitations are feasible. For example, plasmons at an interface of a metal surface and a dielectric medium are called propagating or extended surface plasmons (ESPs), while those in subwavelength metallic nanoparticles are called localized surface plasmons (LSPs).
During the last few years we have been working on developing different structural and system configurations for improving the performance of plasmonic biosensors based on improving the reading method and enhancing the local electromagnetic (EM) field further for the purpose of improving the sensitivity and lowering the detection limit based on SPR, SERS and SEF. The structural improvements include: (i) Planar thin metal films combined with dielectric films in the Kretschmann-Raether configuration, (ii) Periodic metallic structures on planar substrate, (iii) Nanosculptured thin films prepared by the glancing angle deposition technique. (iv) Long range self-referenced plasmonic configurations, and lately, (v) Combination of nanostructures with thin metal films for coupling of extended surface plasmons (ESP) to localized surface plasmons (LSP). The system improvements include: (i) diverging beam approach in the angular mode, (ii) polarimetric spectral mode, (iii) image and signal processing. Particularly we have shown recently that even much higher enhancement of the EM fields (1-3 orders of magnitude) is obtained by exciting the LSPs through extended surface plasmons (ESPs) generated at the metallic film surface using the Kretschmann-Raether and gratings configurations. The largest EM field enhancement and the highest SEF and SERS intensities are obtained when there is perfect matching between the conditions of exciting ESPs and LSPs.
Ibrahim Abdulhalim is a professor in Electrooptic Engineering at Ben Gurion University. He worked in academic institutions and companies such as the OCSC in UC at Boulder, the ORC at Southampton University, the Thin Films Center of the University of Western Scotland, in KLA-Tencor in where he was the lead inventor of optical scatterometry for CD and overlay measurements, Nova and GWS Photonics, His current research involve: LC devices, nanophotonics for biosensing, optical imaging techniques and energy management devices. During the last few years he developed several improved biosensing techniques including SPR, TIR, grating structures and optimized nanosculptured thin films for SERS and SEF. Published over 200 articles, 2 books, 10 chapters and 18 patents. He is a fellow of IoP and SPIE and an associate editor for the Journal of NanoPhotonics and for the Journal of Imaging.