Study Of Nonlinear All-optcial Switching Based On Surface Plasmon Polaritons

Surface plasmon polaritons (SPPs) is an electromagnetic field propagationmode along the metal surface. It has the capacity of controlling light insub-wavelength scale, and it can also locally enhance the intensity of incident light.Therefore, SPPs provides us an effective way to make full use of the nonlinearity ofmaterials. The nonlinear optical devices using metal-insulator-metal waveguide(MIM) were paid a lot of attention in recent decades because of its simple structure,easy integration and so on. In this thesis, MIM waveguide based on SPPs were usedto design and verify a nonlinear all-optical switch.First, MIM waveguide dispersion equations were solved numerically. It isfound that the effective refractive index (ERI) of SPPs can be changed by varyingthe insulator material and the width of waveguide core. When the ERI wasmodulated periodically, there was a band gap appearing in waveguide transmittancespectrum. A metal Bragg waveguide filter was proposed by changing the width ofthe waveguide core and the transmittance spectrum apodization was achieved.Second, with the transfer matrix method and the Bloch theorem, it is verifiedthat a defect mode appeared at the middle of transmission spectrum forbidden bandwhen a defect was introduced into the Bragg waveguide. Based on this feature, aBragg waveguide all-optical switching was designed, and the feasibility wasverified.by Finite difference time domain method (FDTD). Three critical all-opticalswitching performance parameters were discussed, including extinction ratio, thepump light threshold and the response time.Third, the proposed switching has the advantage of easy integration, fastresponse, etc. However, due to the pump and signal overlap in space it’s notconducive for the subsequent optical path to process the signal light. Therefore, thepump light filtering was studied. The main part of this section is analysis ofdouble-stubs metal waveguide filter through the transmission line theory and FDTD.It is found that light with a specific wavelength was filtered by only severaldouble-stubs structural parameters, a MIM waveguide all-optical switching wasobtained based on double-stubs filter, and the separation of pump and signal light inspace was achieved by FDTD stimulation method.Finally, the all-optical switching based on prism structure was simulated usingFDTD. After discussing the relationship between thickness of the dielectric layerand the effect of excitation SPPs in Otto prism structure, the parameters of the prismstructure all-optical switching were identified, the feasibility of the switching was verified, and its main performance parameters were discussed to provide a referencefor the practical application.