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Design of Plasmonic Systems for Nanobiophotonic Applications

Shahmansouri, Afsaneh | 2012

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 43345 (48)
  4. University: Sharif University of Technology
  5. Department: Institute for Nanoscience and Nanotechnology
  6. Advisor(s): Rashidian, Bizhan; Vosoughi, Manouchehr; Shahrokhian, Saeed
  7. Abstract:
  8. In this thesis periodic plasmonic nanostructures are studied for detection of biological specious. The behavior of metal nanostructure arrays under normal incidence has been widely reported. However, simulation of periodic dispersive structures under oblique incidence requires newer formulations. Formulations, and algorithms based on modified split-field finite-difference time-domain (SF-FDTD) method are introduced, permitting analysis of metallic nanostructures arrays under oblique incidence. These novel algorithms are practically implemented on a parallel processing system based on graphics processing unit (GPU). Test and verification of these formulations are done by analyzing referenced metallic periodic nanostructures. Study of plasmonic structures under oblique incidence reveals new feature and important applications. Arrays of nanodisks are investigated in near and far field coupling regimes. The results provide usefull information for designing plasmonic structures. A plasmonic refractive index sensor made of an array of nanoparticles is investigated. It is shown that the refractive index sensing performance can become much better at oblique incidence, compared to normal incidence. FOM up to 33 is achieved at oblique incidence. Plasmonic sensors based on enhanced optical transmission (EOT) have been recently attracted much attention. Optical transmission through double-layer metallic subwavelength holes array is studied under oblique incidence by SF-FDTD method. Both TM and TE polarizations are investigated. Unlike previous claims and reports, it is proved that the transmission peaks can also be observed for TE polarization through SPP excitation. The mechanism of enhanced transmission is fully explored. It is proved that the transmission peak can be tuned by changing the incident angle. Also high transmission is achieved by tuning the SPP excitation with respect to holes transmission. In the application of surface enhanced Raman spectroscopy (SERS) for biomolecular detection, the attentions has been mostly focused on increasing the amplitude of Raman signal. One of the major problems in practical applications of SERS is the lack of repeatability. A solution to this problem is presented in this thesis by introducing “Scanning SERS” method.

  9. Keywords:
  10. Surface Plasmon ; Biosensor ; Finite Difference Time Domain (FDTD) ; Surface Enhanced Raman Scattering (SERS) ; Enhanced Optical Transmission (EOT)

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