Studies of Plasmonic Phenomena and Goos-Hanchen shifts at Metallic-Dielectric interface

• Main Authors: Chih Wei Chen, 陳智偉
• Other Authors: Hai-Pang Chiang
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/39000276590076007740

博士 === 國立臺灣海洋大學 === 光電科學研究所 === 99 === In recent years, Plasmonics is a very interesting research topic. For studies on surface plasmon, we focus on three parts that include (1) Surface Plasmon Resonance (SPR) sensors, (2) optical and spectroscopic properties of metallic nanoparticles and nanoshells, and (3) Goos-Hanchen Shifts. In the first part, we study surface plasmon resonance sensor. We investigated “Temperature dependence of the sensitivity of a long-range surface plasmon optical sensor” theoretically. It is found that the full width half maximum (FWHM) of reflective spectrum and temperature stability of long-range surface plasmon resonance are narrower and more stable then that in case with ordinary surface plasmon resonance. In the second part, we study optical and spectroscopic properties of metallic nanoparticles and nanoshells. The first topic “Effects on the polarizability of mesoscopic metallic nanoparticles” is studied theoretically. We focus on the local and nonlocal effects of temperature and frequency variation on the polarizability of mesoscopic metallic nanoparticles. It is found that the imaginary part of the polarizability always increases with temperature and the real part of the polarizability can both increase or decrease with temperature dependent on the frequency. In addition, the nonlocal effects can be very different for different with the same size for the nanoparticles. The second topic “Nonlocality and particle-clustering effects on the optical response of composite materials with metallic nanoparticles” is studied also theoretically. It is found that the nonlocal effects lead to significant blue-shifted resonances when the particles coalesce. The third topic “Temperature dependence of enhanced optical absorption and Raman spectroscopy from metallic nanoparticles” is again studied theoretically. Numerical results show the temperature dependence of the spectroscopic properties of metallic nanoshells including absorption, scattering, and surface enhanced-Raman scattering (SERS). It is found that the SERS enhancement decreases when the nanoshells get heated up from room temperature and it has greater SERS enhancement rate at low frequency resonance. In the third part, we study Goos-Hanchen(GH) Shifts. The first topic “Large negative Goos-Hanchen shift at metal surfaces” is studied theoretically. Numerical results show that large negative GH shifts can be obtained at incidence close to the grazing angle with TM-polarized light incident onto a semi-infinite metallic medium. Moreover, even at the Brewster angle for long-wavelengths that are still has over 70% of reflectivity for metals, much greater then that studied previously with semiconductors. The second topic “Optical Temperature Sensing Based on the Goos-Hanchen Effect” is also studied theoretically. It is found that the temperature sensor can be effective by using TM-polarized incident light at nearly grazing incidence onto the metal in which variation of negative GH shifts can be observed as a function of the temperature. The third topic “Extremely Large Goos-Hanchen Shifts induced by Long Range Surface Plasmon Excitations ” is also studied theoretically. Numerical results show that a both large negative and positive and a small negative GH shifts are observed on a four layer system correspond to the excitation of the long and short range surface plasmon resonance, respectively. It is also found that the GH shifts by long range surface plasmon resonance excitations is larger than ordinary SPR. To sum up, the three themes (sensors, spectroscopic properties, and GH shifts) of Surface Plasmon are studied theoretically in this thesis.