Design And Characteristic Optimization Of Nano Optical Sensor Based On Surface Plasmon Polaritons

Surface plasmon polaritons (SPPs) is a special electromagnetic mode trapped on the surface of the insulator and metal, furthermore, its energy of light field is biggest at the interface and decays exponentially in the neighboring media. SPPs is a powerful and potential supporting of the information technology and gets more and more attention in the field of the optical communications. SPPs has the advantage of breaking through the diffraction limit in the traditional optics and has a huge field enhancement effect. Optical device based on the surface plasmon polaritons offers the possibility of the integration and miniaturization for the photonic device. Based on the above advantages, nano optical device based on the surface plasmon polaritons has become one of the hot researches in nanophotonics. This paper investigates the optical properties of various metal nano-cavity coupling with waveguides based on the background and MIM (metal-insulator-metal) metal waveguide and uses the simulation software and theoretical analysis for the optimization of the function of the device and parameter of the device.Specific content can be divided into the following sections:1. Introducing the background and related significance of the paper and research course and related applications about SPPs. Besides, the paper introduces the free electron gas model and common waveguide structure of surface plasmon polaritons and surface plasmon MIM waveguide.2. The paper introduces nano-optical sensor and the finite element method and the finite element method with COMSOL Multiphysics. The conditions and the common method of the excitation of SPPs is deduced in detail. Besides, the transmission properties of SPPs are introduced,which provides a reference for the design of structural parameters.3. Investigating the Fano resonance based on MIM waveguide. The paper uses the waveguide coupling rectangular cavity and the Slot cavity,getting the profile of the double Fano and explains the Fano resonance with the relation of the related the parameter of the structure qualitatively and quantitatively based on the theory of the standing wave,simultaneously, we have a good tuning of the Fano resonance by the finite element method with COMSOL Multiphysics by investigating the parameters of the structure. In addition, we gain the three Fano profiles by the asymmetric expanding of the structure based on the existing physical knowledge and can tune the resonance peak of Fano by the theoretical analysis. At last, through the regulation of the structure can be well adapted to the experiment and nano-optical sensor will have a good sensitivity of 800 nm/RIU and FOM of 1.35×104 by the proposed structure.4. The paper gain the double resonance profiles of Fano by the simple coupling of the stub cavity and single rectangular cavity and has a numerical simulation and theoretical analysis for the structure by the finite element method with COMSOL Multiphysics. The paper has a try of qualitatively analyzing for the profile of Fano by the standing wave theory and have a good tuning of the peak of double Fano resonance by the analysis structure. At the same time, we have expanded the structure by the existing knowledge and gain the origin and regulate the multiple Fano resonance independently. This paper gains the peak of Fano resonance by the simple metal stub cavity and single rectangular cavity,which can be designed nano optical sensor with a sensitivity of 1900nm/RIU and FOM 3.8×104.In summary, we gain the single, double, multiple profiles of Fano resonance by the coupling of the rectangular metal cavity, stub cavity and single rectangular cavity based on the MIM waveguide and have a good simulating and analyzing the origin of the peak of every Fano resonance and realize the regulation of the profile of Fano resonance by the finite element method with COMSOL Multiphysics. Nano optical sensor designed by using the characteristic of peak of the Fano resonance has the ultra-high sensitivity and high FOM, which has a good reference for designing the nano optical sensor and realizing the designing for the nano optical device based on the scale of the micro-nano.