Plasmonics can be applied in a wide range of optoelectronic devices and it is induced by the interaction between incident light and conduction electrons. Resonance is induced by matching the photon energy and the frequency of electrons, which can cause the surface charge distribution and strengthens the electromagnetic field. Generally, plasmonics can be classified into surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR). SPR is the propagating wave, which occurs at interface between the dielectric and metal. LSPR is the non-propagating wave, which is the interaction between the metal nanoparticles (NPs) and incident light when the NP size is smaller than the light wavelength. In this thesis, plasmonic enhancement is studied to improve the performance of organic solar cells (OSCs) and light emission of organic semiconductors. OSCs are low cost, light weight, flexibility, and solution process ability at room temperature. Short exciton diffusion length limits the thickness of active layer, which causes low photon absorption and consequently low current generation. In this part, gold nanoparticles (Au NPs) are blended into OSCs to enhance photovoltaic performance. Au NPs can induce the localized surface plasmon resonance (LSPR) which enhances the light absorption due to electromagnetic field generation. Also, light can be trapped by scattering to increase the optical path and thus enhance the charge carrier generation. Film structure and 1D nanostructure of organic semiconductor are studied by their photoluminescence (PL) intensity. Generally, the PL intensity can be enhanced by SPR. Excitation energy can induce the surface plasmon (SP) instead of photon, which can amplify the spontaneous emission and stimulated emission. Compared to thin films, 1D organic structures achieve higher PL enhancement because they can trap the light more efficiently by Fabry-Pérot cavity. Different morphologies of organic semiconductor are synthesized and it is found that hexagonal plates can obtain better PL enhancement because of the Fabry-Pérot cavity mode. / published_or_final_version / Physics / Master / Master of Philosophy

Ling, Chi Wai = 在等離子體鏈中使光變慢 / 凌志偉. / "September 2010." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (p. 73-76). / Abstracts in English and Chinese. / Ling, Chi Wai = Zai deng li zi ti lian zhong shi guang bian man / Ling Zhiwei. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Slowing down of light --- p.1 / Chapter 1.2 --- Objectives of the thesis --- p.4 / Chapter 2 --- Review on Bergman-Milton Theory of Green Function --- p.5 / Chapter 2.1 --- Green function for Laplace operator --- p.5 / Chapter 2.2 --- Integral equation for two-component systems --- p.6 / Chapter 2.3 --- Symbolic solution for two-component systems --- p.10 / Chapter 2.4 --- An isolated dielectric sphere --- p.11 / Chapter 2.5 --- Extension to a collection of multi-interacting spheres --- p.13 / Chapter 3 --- Slowing Light by Multipolar Effect in Metal Nanoparticle Chains --- p.16 / Chapter 3.1 --- Evaluating the dispersion relations --- p.17 / Chapter 3.2 --- Results and discussions on multipolar effects --- p.20 / Chapter 4 --- Level Repulsion Phenomenon --- p.23 / Chapter 4.1 --- Two coupled oscillators --- p.24 / Chapter 4.1.1 --- Normal mode method --- p.24 / Chapter 4.1.2 --- Forccd oscillator method --- p.25 / Chapter 4.2 --- Metallic nanoshells --- p.25 / Chapter 4.3 --- Two coupled metal nanoparticles --- p.27 / Chapter 4.4 --- Diatomic spring-mass chain --- p.28 / Chapter 4.4.1 --- Dispersion relation --- p.29 / Chapter 4.4.2 --- Forced oscillator method --- p.30 / Chapter 5 --- Slowing Light by Hybridization of Bands in Plasmonic Chains --- p.34 / Chapter 5.1 --- Coupled dipole equation of plasmonic Chains --- p.34 / Chapter 5.2 --- Monatomic metal nanoparticle chains --- p.36 / Chapter 5.3 --- Diatomic chains formed by unshcllcd metal nanoparticles and shelled metal nanoparticles --- p.39 / Chapter 5.3.1 --- Formalism for evaluating dispersion relation --- p.39 / Chapter 5.3.2 --- Hybridization of bands --- p.42 / Chapter 5.3.3 --- Stopping light using photon-phonon assisted proccss --- p.45 / Chapter 5.3.4 --- Discussions --- p.47 / Chapter 5.4 --- Monatomic chains formed by nanoshells --- p.49 / Chapter 5.4.1 --- Formalism --- p.50 / Chapter 5.4.2 --- Numerical results and discussions --- p.54 / Chapter 5.4.3 --- Conclusions --- p.57 / Chapter 5.5 --- Diatomic chains formed by two types of dielectric shelled nano- particles --- p.60 / Chapter 5.5.1 --- Formalism for evaluating dispersion relation --- p.60 / Chapter 5.5.2 --- Results and discussions --- p.63 / Chapter 5.6 --- Yin-yang plasmonic chain --- p.68 / Chapter 6 --- Summary --- p.71 / Bibliography --- p.73 / Chapter A --- Properties of operator Γ --- p.77 / Chapter A.1 --- Hermitian Property of operator Γ --- p.77 / Chapter A.2 --- Eigenfunctions and eigenvalues of operator Γ for isolated spheres --- p.78 / Chapter B --- Drude Model and Polarizabilities of Spheres --- p.82 / Chapter B.1 --- Drude Model --- p.82 / Chapter B.2 --- Polarizabilities of spheres --- p.83 / Chapter C --- Dyadic Green's Function --- p.85

Surface plasmons¡]SPs¡^have been extensive applied to various kinds of detector and devices. There are very great relations of physical quantity, such as resonant angle, damping rate, halfwidth of resonance and reflection rate, etc. of resonating in the exciting of SPs. In this study, we derived some approximate formulas of these physical quantities from fresnel¡¦s formulas and pole approximate expansion, such as, the damping rate of SPs, the resonant angle, the optimum metallic thickness of these structure. In addition, we have also proceeding to some numerical simulations. Surface plasmons can also apply to near-field optics, using the super-resolution near-field structure¡]Super-RENS¡^ , the data densities can be promoted, and the diffraction limit can be overcome. SPs are excited at the Sb/SiN interface may concentrate light spot and enhance the field intensity. In this study, we have also expounded the fact that its antimony film in a Super-RENS of propagation, function and simulation of the SPs. As a result of calculations and simulations, we conclude that the enhanced filed intensity is larger for a system using a metal with a smaller imaginary part of the dielectric constant. The resonant angle decreases when the dielectric constant of the prism increases and the dielectric constant of the intermediate layer decreases. In addition, the optimum resonant condition in Super-RENS can be made by proper selection of parameters.

Thèse de doctorat : Physique : Strasbourg : 2009. / Titre provenant de l'écran-titre. Bibliogr. 13 p.

Thèse de doctorat : Physique : Strasbourg 1 : 2008. / Titre provenant de l'écran-titre. Bibliogr. p. 107-119.

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (p. 133-139).

Thesis (Ph. D.)--University of Chicago, Dept. of Chemistry, August 2001. / Includes bibliographical references. Also available on the Internet.

Metallic films with narrow and deep subwavelength gratings or holes having a converging-diverging channel (CDC) can exhibit enhanced transmission resonances for wavelengths larger than the periodicity of the grating or hole. Using the finite element method, it is shown that by varying the gap size at the throat of a CDC, the spectral locations of the transmission resonance bands can be shifted close to each other and have high transmittance in a very narrow energy band. Additionally, the transmission of light can be influenced by the presence of the externally applied magnetic field H. The spectral locations of the transmission peak resonances depend on the magnitude and the direction of H. The transmission peaks have blue-shift with the increase in H. A new multilayer thermal emitter has been analyzed in the visible wavelength range. The proposed emitter has large temporal and spatial coherence extending into the far field. The thermal emitter is made up of a cavity that is surrounded by a thin silver grating having a CDC on one side and a one-dimensional (1D) photonic crystal (PhC) on the other side. The large coherence length is achieved by making use of the coherence properties of the surface waves. Due to the nature of surface waves the new multilayer structure can attain the spectral and directional control of emission with only ppolarization. The resonance condition inside the cavity is extremely sensitive to the wavelength, which would then lead to high emission in a very narrow wavelength band. In addition a new tunable plasmonic crystal (tPLC) was proposed, where the plasmonic or polaritonic mode of a metallic array can be combined with the photonic mode of a hole array in a dielectric slab for achieving negative refraction and still posses an extra degree of freedom for tuning the tPLC as a superlens to operate at different frequencies. The tunability of the single planar tPLC slab is demonstrated numerically for subwavelength imaging (FWHM 0.38[lambda]~ 0.42[lambda]) by just varying the fluid in the hole array, thereby enabling the realization of ultracompact tunable superlens and paving the way for a new class of lens. An aggressive pursuit for decreasing the minimum feature size in high bandgap materials has lead to various challenges in nanofabrication. However, it is difficult to achieve critical dimensions at sub-wavelength scale using traditional optical lithography. A new technique to create submicron patterns on hard-to-machine materials like silicon carbide (SiC) and borosilicate glass with a laser beam is demonstrated. Here the principle of optical near-field enhancement between the spheres and substrate when irradiated by a laser beam has been used for obtaining the patterning.

Tailoring surface plasmon (SP) resonances using metallic nanostructures for optical manipulation has been widely investigated in recent years; and there are many puzzles yet to be solved in this relatively new area. This thesis covers the study of the interaction of light with SP-supporting planar/patterned metallo-dielectric multilayer structures. Two separate, but closely related subjects were investigated using such structures, which are: SP-assisted optical transmission and optical metamaterials. The physical mechanisms of the SP-assisted transmission phenomenon were studied using planar/grating and planar/hole-array multilayer structures. Extraordinary light transmission has been demonstrated through experimental work and simulations for both arrangements; and the effects of different structural parameters on the transmission efficiencies of the structures were analyzed systematically. The interplays of the surface plasmon polaritons (SPPs) and localized surface plasmons (LSPs) in the extraordinary optical transmission (EOT) phenomenon were identified. The potential of the planar/hole-array multilayer structures as optical magnetic metamaterials was evaluated using two independent electromagnetic simulation techniques. The ability of such structures to produce strong magnetic resonances from infrared down to visible side of spectrum was revealed. The methods of tuning the magnetic response of the structures were suggested. A novel design of optical metamaterial based on high-order multipolar resonances in a single-layer plasmonic structure was also proposed. Numerical results from two different computation methods indicate that a simultaneously negative permittivity and permeability can be achieved in such a structure.

At the interface between a metal and dielectric, it is possible for an electromagnetic wave to couple with the conduction electrons of the metal to create a coupled oscillation known as a surface plasmon. These surface plasmons can exhibit properties which are not shared with their purely electronic or electromagnetic components. Such unique properties include the ability to transmit plasmonic waves through sub-wavelength spaces, opening up the possibility of combining the high data density seen in photonics-based information technologies with the nanometer-scale electronic components of modern integrated circuitry. Other plasmon properties such as the highly resonant nature of plasmon excitation may potentially lend themselves to novel cancer treatments and medical probing techniques. In order to develop such technologies, a deeper understanding of surface plasmons and their relationship with a material’s properties and structure is necessary. In the present work, angle- and energy-resolved optical measurements for a square lattice of circular Fe20Pd80 islands are presented in the form of reflectivity and transmission maps, along with higher resolution reflectivity, transmission, and TMOKE measurements for a few specific wavelengths. A theoretical model describing the connection between plasmonic and magneto-optical behavior is described and compared with the experimental data, showing a very high correlation.