Department of Electrical Engineering
University Oral Examination
Optical Nonspecular Effects at Surface Plasmon Resonance and their Applications
Xiaobo Yin
Research Advisor: Lambertus Hesselink
1:00pm May 22nd 2008 (Refreshment at 12:45pm)
Hansen Experimental Physics Laboratory (HEPL), Room 102 (The New Attachment to the
Abstract
The experimental observation of the Goos-Hänchen effect, a lateral beam shift at total internal reflection, has stimulated many interesting studies on optical nonspecular phenomena. These include the angular shift of the beam axis and the secondary nonspecular effects of shift in beam focus and beam waist modification. However, most of these investigations are focused on the geometrical parameters which lead to spatial nonspecular effects. In this talk, the temporal nonspecular effect as well as its spatial counterparts will be analyzed in an attenuated total internal reflection device where surface plasmon resonance (SPR) is optically excited. The physical quantities associated with these phenomena are identified and examined experimentally. New observations such as negative Goos-Hänchen displacement and superluminal pulse propagation at plasmon resonance will be discussed.
With improved and new understanding of the nonspecular effects at resonance, several applications of the effects will be proposed. Specifically, a Goos-Hänchen effect based biochemical SPR sensor (ghSPR) will be discussed in detail. Due to the singular behavior of the effect at plasmon resonance, the sensor achieves a superior sensitivity (up to 100x) compared to the conventional, reflectivity based SPR sensor. Two prototypes of ghSPR sensors with and without optical amplifications are demonstrated. Such sensors are potentially very useful in many applications such as disease marker screening and drug purification. As an example, low affinity antigen recognition is performed as a proof-of-principle experiment.
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