Theoretical Studies On Surface Plasmon Poliriton Whispering Gallery Microcavity And Fabrication Of Dielectric Microsphere

In recent years, Whispering-gallery (WG) microcavities have attracted many researchers’ attentions. In view of ray optics interpretation of WG mode that a light ray orbiting inside a microresonator is due to total reflection at the resonator boundary. Benefitted from WG mode of the microcavities, the light can be confined inside the microcavities so well that the energy density is greatly enhanced. Such devices with ultrahigh quality factor (Q), ultrasmall mode volume (V) and relatively simple process play central roles in areas which demand ultrafine line width, ultrahigh energy density and ultrasubtle detection capability, including nonlinear optics, quantum optics, and device physics (e.g., sensors, lasers...).In this thesis, we fabricated the dielectric microsphere experimentally and studied surface plasmon polariton microcavity and waveguide, the main research works are as follows:Firstly, we introduce the progress, applications and WG mode of the microcavities in recent years in detail, and analyze the eigenmode equation and basic parameters of the WG mode.Secondly, we fabricated the dielectric microsphere and tapered fiber waveguide using the fusion method by a CO2laser. The diameter of the microsphere tapered fiber ranges from20-120μm and1-3μm, respectively. The microsphere coupling system had been conducted with the tapered fiber waveguide.Again, we theoretically analyzed the surface plasmon polariton whispering gallery microcavity, including:◆We propose a novel hybrid plasmonic microcavity which is composed of a silver nanoring and a silica toroidal microcavity. The hybrid mode of the proposed hybrid plasmonic microcavity due to the coupling between the surface plasmon polaritons (SPPs) and the dielectric mode is demonstrated with a high quality factor (>1000) and an ultrasmall mode volume (-0.8μm3). As a potential application, the hybrid mode could be used for a biosensor with a sensitivity high of up to500nm per refraction index unit and a wide detection range.◆We theoretically propose a hybrid microresonator consisting of a metallic wedge ring and a silica ring and investigate the existing whispering-gallery-like hybrid wedge plasmon polariton modes. These tightly confined hybrid plasmon modes are found to possess ultrasmall mode volumes while maintaining relatively high quality factors simultaneously at room temperature; that is, high values of QV are obtained. For example, a Purcell factor of70is achieved at the telecommunication wavelength of1550nm.◆A kind of surface plasmon polaritions metal-coated microdisk resonator is theoretically simulated and optimized by using a finite element method. The quality factor and mode volume of the plasmonic mode of the microdisk are theoretically investigated by considering different parameters of the microdisk such as the bottom radius, the thickness of dielectric, and the thickness of metal coating. High quality factor(>1000), ultrasmall mode volume surface plasmon polaritions microcavities are achieved for the telecommunication wavelength of around1550nm.Finally, we theoretically analyzed the surface plasmon polariton waveguide, including:◆A novel hybrid plasmonic waveguide (HPW) based on a metal ridge and a semiconductor nanowire is proposed and analyzed theoretically. Our simulations show that mode area as low as λ2/1600which is about three orders of the magnitude smaller than the diffraction-limit area in free space has been achieved for the proposed HPW.