Research On The Characteristics Of Surface Plasmon Polaritons Resonators And All-Optical Modulation Of Surface Plasmon Polaritons

Obtaining optical waveguide and optical modulator which are beyond the diffraction limit is the foundation of integrated nanophotonics. Surface plasmon polaritons (SPP) resonant cavity combine the properties of SPP with resonant cavity's characteristics, so it provides an opportunity to realize compact SPP resonator with high Q factor and ultrasmall mode volume. High sensitivity, ultrafast and low threshold value optical switching can be achieved for SPP has significant field enhancement. SPP resonant cavity and all-optical SPP modulator have potential application in nanophotonics components, integrated nanophotonics circuit and bio-photonics. In this thesis, using the simulation algorithm and experiment, the physical mechanism of SPP resonant cavity and SPP all-optical modulation are analyzed, and some innovative applied designs are proposed.The main research works and conclusions are as following:1. The dispersion relation and mode's characteristics of metal-dielectric-metal (M-D-M) are analyzed with waveguide theory, and the relation between the thickness of dielectric and mode's characteristics are also be derived. It is found that the two lowest TM modes are corresponding to symmetric surface plasmon polaritons (SPP(0)) mode and the antisymmetric surface plasmon polaritons (SPP (1)) mode. The results also show SPP(0) has no cut-off width, while SPP(1) not only has cut-off width but also has critical width. We proposed SPP mode's phase modulation with the parameters of metal-dielectric structure which is the foundation of all-optical SPP modulation. Introducing nonlinear optical material into M-D-M device, we studied the properties of metal-nonlinear dielectric-metal (M-NLD-M) structure. The relation between the propagation constants of the two SPP modes and incident light intensity are studied with the dispersion relation of M-NLD-M device. Using modulation of the two SPP modes's propagation constants difference with incident light intensity, the dual channel optical switching is realized. The SPP beam splitter is proposed with M-NLD-M arrays consisting of slits with variant widths. Based on Fabry-Perot resonance and the third nonlinear effect, the splitting angle can be controlled by the phase difference change of M-NLD-M elements with the incident light intensity.2. The dispersion relations, mode's properties, phase velocity, and the propagation loss are investigated with theoretical analysis and Boundary integrated method (BIM). The research shows that the phase velocity of SPP mode along a concave interface (metal-dielectric) is faster than that of a planar one. On the contrary, the phase velocity of a convex interface is always less than that of a planar one. It is also found that the propagation losses of curved interface are larger than that of a planar one. These results are playing significant role in design SPP resonant cavity. We analyze the method of improving the extinction ratio of SPP resonant cavity, and designed race-track SPP resonant cavity with high extinction ratio. The coupling resonant properties of M-D-M waveguide to the race-track resonator at 1.55μm are studied with structure's parameters. An extinction ratio of -34.5dB can be achieved at the critical coupling point. Such a SPP resonator design provides a promising realization fro nano-integration, sensing and high effective modulators. We use coupling equation of modes in time and nonlinear perturbation theory to investigate the optical bistability phenomenon of race-track SPP resonator. Based on these theoretical analyses, race-track SPP resonator switch with high contrast is proposed. A fast response speed of 0.38ps and a high contrast of 97.8% can be achieved with pump intensity of 1.748MW/cm². The results provide fundamental research to realize compact SPP all-optical modulators with high speed, low threshold value, and high contrast.3. The characteristics of SPP modes, Q factors, and effective mode volumes of three silver nanowire structures are studied by Finite Element Method (FEM). The silver nanoring-dielectric-silver film SPP resonator with high Q factor and ultrasmall mode volume (V_eff) is proposed based on above research of silver nanowire structures. The dependence of field distribution of Gap mode,Q factors, and effective mode volumes in the SPP resonator on its structure parameters are investigated. By optimizing the parameters of structure, the V_eff of 0.0083μm³ and Q/V_eff of 1.6×10⁴μm?3 can be achevied. This research is beneficial to the development of integrated chip SPP sensing ,active nano device, and integrated technology .4. The dispersion relation and propagation properties of SPP at anisotropic uniaxial crystal-metal interface are investigated theoretically. The research shows that the properties of SPP at anisotropic uniaxial crystal -metal interface have relationship with the optical axial (OA) orientation of anisotropic uniaxial crystal, and the OA orientation of the uniaxial medium in the incident plane (XZ-plane) has stronger influence on SPP's properties than the case where the OA is in the interface plane (XY-plane). The experiment is designed to demonstrate the theoretical results. The results of this research have significant meaning for study of SPP's physic mechanism excited at metal-anisotropic materials and all-optcial switching. We studied all-optical modulation of prism-silver film-azobenzene polymer film with Krestschmann-Raether structure. Modulation contrast of 47.74% can be obtained with proper polarized pump light.Highlights of the dissertation are as following:1. We proposed improving the extinction ratio of SPP resonator with increasing the coupling length. Based on this, race-track SPP resonator with high extinction of -34.5dB is designed. Using coupling equation of modes in time and nonlinear perturbation theory, we investigated the optical bistability phenomenon of race-track SPP resonator. Based on these theoretical analyses, race-track SPP resonator switch with high contrast is proposed. A fast response speed of 0.38ps and a high contrast of 97.8% can be achieved with pump intensity of 1.748MW/cm2.2. Based on the characteristic of SPP mode, we designed silver nanoring-dielectric-silver film SPP resonator to improve Q factor and decrease mode volume (V_eff). By optimizing the parameters of structure, the V_eff of 0.0083μm³ and Q/V_eff of 1.6×10⁴μm^-3can be achevied.3. According to the physic mechanism of SPP excited at metal-anisotropic materials interface and all-optical switching, the dispersion relation and propagation properties of SPP at anisotropic uniaxial crystal-metal interface are theoretically investigated, and we designed experiment to demonstrate the theoretical results. Based on these results, all-optical modulation with high modulation is studied with prism-silver film-azobenzene polymer film structure.