Study Of Key Technologies Of Manipulating Light Propagation Of Surface Plasmon Waveguide

In order to meet the need of the development for integrated optics,nano-scale integrated photonic devices with newly physical effects has become the frontier and hot topic in optics.Surface plasmon structrues and devices,in which photons can be manipulated in nano scale,can provide a good solution to highly nano-photonic integration.And international attentions have been paid to this field,which include the class of electromagnetically induced transparency,nonlinear effect enhancement,surface plasmon resonance sensor etc.While there are some disadvantages in the researches,such as the polarization of the incident electromagnetic wave,roughness of surface,narrow-band and so on.Thus,this dissertation will focus on the research of manipulating light propagation of surface plasmon waveguide.Main research contents are as follows:1.Polarization-independent Plasmon-induced TransparencyRecently,all-optical analogue to EIT effect has also been achieved in plasmonic-based coupling systems.The mechanism of this plasmonic-induced transparency can be understood from two ways,where the first understanding is based on the coupling between the radiative and dark state supported respectively by two plasmonic “atoms”,and the second comprehension is based on the exciting of trapped mode supported by asymmetric structures.Meanwhile,the first and the second mechanism of EIT are both polarization dependent.The paper proposes a coupling system consisting of tow-dimensional(2D)lattice cross-slit metallic photonic crystals and dielectric photonic crystals embedded in a background material to achieve plasmon–induced transparency.For the plasmonic structure,the electric and magnetic response to the normally incident plane electromagnetic(EM)wave with TE polarization is the same as that to the plane EM wave with TM polarization due to the symmetry of the structure,so the EIT-like of structure is polarization-independent and Numerical simulations indicate that one of the transmission resonance dips for the compound system is very sensitive to the background material.Meanwhile,polarization-independent transparency of the structure makes the coupling system possess great potential for achieving high-performance sensors.2.Enhancement of nonlinear response of a silicon waveguideIn this dissertation,numerical simulations demonstrate that nonlinear optical response in a thin silicon waveguide within a wide wavelength regime can be enhanced by a metal grating,that the enhancement factor of light generation at the four-wave mixing varies with the position.The largest enhancement factor of 10400 can be achieved at a certain position in the spectrum with proper geometric parameters.More importantly,the wavelength of light generation at four-wave mixing with the same enhancement factor can be controlled dynamically within a wide wavelength regime.3.Plasmon-based perfect absorptionThe inevitable losses in plasmonic metallic nanostructures block its further practical application.Recntly,the concept of perfect absorption turns this disadvantage of metal loss into advantage,which can be used to carry out other research;one is perfect absorber.In this dissertation,a plasmonic structure is proposed to achieve dual-band perfect absorber.Numerical simulations indicate that there are two absorption peak at wavelength 1565 nm and 1998 nm with absorptivity 99.93% and 99.86%,respectively,near perfect dual-band absorber?4.Localized Surface Plasmon Resonance Sensor(LSPR)It is well known that when interacting with electromagnetic radiation,the collective electronic oscillation in metal nanoparticles can give rise to localized surface plasmon resonance(LSPR).The LSPR strongly depends on the shape,material,size,and surrounding dielectric environment of the nanostructures.The latter dependence makes them especially attractive for refractive index sensing.In this dissertation,we explore two plasmonic structures to achieve LSPR.One plasmonic structure consists of metal(Ag)strip pairs array,another consists of cross-slit metallic periodic arrays,and both structures are placed within a background dielectric.While,for the plasmonic structure consisting of cross-slit metallic periodic arrays,the electric and magnetic response to the normally incident plane electromagnetic(EM)wave with TM polarization is the same as that to the plane EM wave with TE polarization due to the symmetry of the structure,thus a polarization-insensitive sensor can be obtained.