Research Of Multiple-Slit And Groove Structure Photodiode Based On COMSOL

Photodiode is the most fundamental photonic device in the integrated photonic circuit,thus if modulated photodiode is developed,it will be of great significance inevitably for prospective manufacture of complicated photonic circuit.This paper is aimed at modulating sub-wavelength metallic silver structure by simulation software COMSOL Multiphysics to control SPPs dynamically, making transmissivity of light enhance or inhibit and obtaining the structure with the best Unidirectional light transmission.SPPs is a kind of electromagnetic wave along the metal surface. Under the micro-nano order of magnitude, SPPs has many unique optical properties that possess high research and application value in the micro-nano optical field. Extraordinary optical transmission phenomenon has attracted much attention as it reaches the diffraction limit that traditional optics can't break through. This work focus on modulating SPPs by adjusting structure geometric parameters on the basis of further analyzing EOT phenomenon, finally achieve the biggest extinction ratio in the wavelength range as wide possible as,namely the best unidirectional transmissivity.The main work is as follows:(1)Analyse single slit structure,the simplest sub-wavelength structure,by a numerical simulation software COMSOL Multiphysics based on finite element method and obtain a optimization model of single slit structure.(2)Add a groove structure to model based on single slit structure leads to asymmetry and unidirectional transmissivity. Then simple optimization model is obtained by adjusting and optimizing the distance of single slit and single groove.(3)The influence of periodic slit and groove sub-wavelength structure on extraordinary optical transmission is studied, It is found that it makes no obvious difference to the peak of extinction ratio when the shape of groove is shifted but the wavelength of the biggest extinction ratio will be changed, this outcome has reference value for application of structure in the range of microwave in the future.(4)Research the extinction ratio of multiple-slit and multiple-groove structure.The biggest extinction ratio has reached up to 50 dB in this article, in other words, positive optical transmissivity is 100000 times more than reverse transmissivity. It plays an important role in the further study of light diode manufacture.