Mode Field And Coupling Properties In The Micro-cavity Structure Of Metal-dielectric/metal

A metal-dielectric interface supports the Surface Plasmon Polariton (SPP) modes,yielded by the coupling of the electromagnetic field with the coherent oscillations of thefree electrons in the metal. Its ability to propagate and control light at thesub-wavelength scale is essential for many applications such as sensing, photoniccircuits. In metallic nanostructures, the coupling between the SPP mode and otherresonance modes can realize the manipulation of photons. In this thesis, the mode fieldsand their coupling in the micro-cavity structure consisted of metal-dielectric/metal wasinvestigated.First, characteristics of modes in Metal/Dielectric/Air (MDA) structure werestudied by Transfer Matrix Method (TMM). In the cavity, the modulation of the modesthrough changing the refractive index and length of the resonator was analyzed. Theresults were that the excited angle of the SPP could be shifted continuously by thelength of the cavity.When a metal layer was introduced into the above composite structure, the cavityproperty was changed, and then leading to the broadening excited angle. And it alsocaused a coupling between the cavity modes and the SPP mode, which induced theoccurrence of an anti-crossing behavior. Furthermore, we analyzed the1st-order modeand the0th-order mode. The1st-order mode was divided into three parts according tothe value of mode effective index. Especially, when the effective index was larger thanthe n of the dielectric, the1st-order mode was a SPP mode. The degeneration such a1st-order mode and the0th-order mode occurred, at the condition of a longer cavity.Finally, the modulation of SPP by the metal grating was studied using RigorousCoupled-Wave Analysis (RCWA). Modes field and their coupling were discussed in thestructure of metal-dielectric/metal grating. Degeneration between the1st-order modeweakened as the increase of the cavity length.