Research On Surface Plasmon Polaritons Controlled By Kerr Effect

Surface plasmon polaritons (SPPs) are propagating electromagnetic waves associated with the collective motions of conduction electrons confined to metal-dielectric interfaces. Its subwavelength confinement can be applied to design nano-photonic devices that break the diffraction limit, making it feasible to achieve high-integrated and superminiature photonic chips. The properties of SPPs depend strongly on the sizes, the shapes and the dielectric environments of metallic nanostructures, which lays foundation both for developing ultra-sensitive biological detectors/sensors, and for designing photonic devices at nanoscale.In this thesis, Kerr effect’s control on SPPs is studied theoretically based on the subwavelength confinement and the local electromagnetic field enhancement of SPPs. In addition, a series of nano-photonic components are designed based on SPPs, including micro-nano focuser, micro-nano polarizing filter and micro-nano multi-channel bandpass filter. This thesis contains four parts.1. Design of controllable focuser based on Kretschmann configuration. Optical bistability can be achieved when Kerr effect is induced in Kretschmann configuration. As a focusing structure is integrated with this kind of Kretschmann configuration, the size of focused spot and the depth of focus will be controlled bistably by incident intensity (focal length will be the same), and they are confined in subwavelength scales.2. Design of polarizing filter based on nano-hole array of silver film. SPPs modes depend on the size and the dielectric constant of waveguide. Accordingly, as Kerr medium segment is filled into these special nano- holes, output modes with constant polarization orientation will be controlled by incident intensity. The mechanism of output intensity being controlled bistably by incident intensity has also been analyzed, when Kerr effect is induced in nano-holes.3. Design of multi-channel bandpass filter based on MIM waveguide structure. Three cascaded dielectric cavities are placed in MIM waveguide structure and SPPs modes inside interact. As a result, new unite resonant modes will appear and the free spectral range (FSR) will narrow down accordingly. As Kerr effect appears in these cascaded cavities, output resonant wavelength can be controlled by incident intensity, which will contribute to a more flexible application of the filter.4. Synthesis of low dimensional metallic nanostructures. A series of metallic nanostructures, which are uniform in size and shape, are synthesized through sol-gel method. These nanostructures with good crystal structures, few defects and low surface roughness are ideal experimental samples for SPPs’research.