Research Of Modulator Based On Surface Plasmon Resonance

The surface plasmon is an electromagnetic wave propagating along the surface of the metal and dielectric interface.Utilizing the characteristics of special locality and near field enhancement of SPPs,the light can be localized in the subwavelength scale.Under phase-matching or resonance conditions,the collective oscillation of free electrons can be realized on the metal surface.At this time,most of the energy of the incident light wave can be absorbed by the free electrons and the intensity of reflected light can be reduced to a certain extent.This energy-transfer phenomenon can be achieved with p-polarized light.The surface plasmon is highly sensitive to the changes of refractive index of medium;Non-linear polymer material has Kerr effect and linear polymer material has electro-optic effect.So the integration of the surface plasma wave and polymer material can yield waveguide structures,which have great research and application value in the field of photonic devices.The modulator structure based on ATR total reflection structure is proposed and numerically investigated using the finite-difference time-domain simulation.Moreover,the resonance characteristics of the modulator structure based on the theory of surface plasmon are deeply studied and analyzed.The results can provide theoretical principle for the fabrication of photonic devices.First of all,the optical properties of metal are introduced and analyzed.Moreover,the generation mechanism and the excitation mode of the surface plasmons are discussed.Then,three dimensional finite difference time domain method used is analyzed in this paper.Then,an all-optical modulator based on long-range surface plasmon resonance with metal nano-wires array and respect to Kerr effect induced refractive index changes is proposed and numerically investigated using the finite-difference time-domain simulation.The all-optical modulator is realized with low intensity of pump light.The geometric parameter,the temperature,the metal nanoparticles and the intensity of pump light have a significant influence on the reflectance spectra of all-optical modulator,respectively.Thecoupling performance of the all-optical modulator is improved by allocating the parameters of metal nano-wire and buffer dielectric layer reasonably.On this basis,the reflection characteristics of all-optical modulator are investigated with different intensity of pump light.Finally,an electro-optical modulator with much higher modulation index based on a total internal reflection structure is proposed and numerically investigated using the finite-difference time-domain simulation.The optical signal is controlled by different operating voltage of the electrode.The structure is analyzed based on finite difference time domain method,the electric field distribution and the reflectivity curve of spectrum are obtained,respectively.The results show that the mode coupling ability of the electro-optical modulator is the optimal.With the increase of driving voltage,the red shift of the absorption peak of the reflectance spectra is obvious.The higher modulation index can be achieved with a low operating voltage.