The Characteristics Research Of Optical Field Modulation Based On Surface Plasmon Polaritons

Surface plasmon wave(SPW)or surface plasmon polaritons(SPP),is a kind of electromagnetic wave propagating along the interface of metal-dielectric,which can have breakthrough on the conventional optical diffraction limit.It has strong local field enhancement effect,and can realize optical focus,modulation,beam splitting and filtering for incident light on the scale of nanometer.The nano-cavity resonator and metallic grating structure have become hot topics in recent decades.By restricting the SPP with specific wavelength in the nano-size cavity,and analyzing the distribution of light field,the resonator can output the needed wavelength exactly.Transmission or reflection spectrum and light field’s distribution are common presentation method and analysis tool for SPP’s propagation.Firstly,we illuminated Metal-Insulator-Metal(MIM)waveguides and nano-cavity structures on the excitation mechanisms and transmission features.By investigating copious literatures for the plasmonics filter,wavelength division multiplexing(WDM)and beam deflector,and combining the theoretical derivation with numerical simulation,we have proposed several new nano optical devices with high performance.The main work and innovation points are listed below:1.Based on the plasmonic nano-cavity theory,we designed a new WDM on the silver film whose size is 1.5 μm×1.2 μm.It can pick out 1310 9)9)8)8),1490 9)9)8)8)and 1550 9)9)8)8)from continuous wave and separately output these wavelengths in low cross-talk,which will be a good choice for high-integrated WDM system in the future.2.Based on the plasmonic nano-cavity theory,we designed an ultra-high resolution filter on the silver film whose size is 1.1 μm×0.75 μm.The FWHM of the transmission spectrum can be lower than 7 9)9)8)8),namely,the resolution has been greatly improved.3.Based on the filter structure proposed above,we designed an optical modulator by introducing a new input port to the filter,which can achieve simple logical operation.4.We designed a new beam deflector,optical coupler and PBS.By adjusting the configuration’s parameters,we can get arbitrary deflection angle that we need.The coupler’s efficiency for TM mode can approach to 80.73%,while TE mode will be totally reflected,which means the coupler also can act as a PBS.