Research On The Coupling Of Short Range Surface Plasmon Polariton In Waveguide Structure And Its Application

Short Range Surface plasmon polariton （SRSPP） is a kind of specialtransverse magnetic （TM） surface electromagnetic wave guided along with thinmetallic film. SRSPP has a highly concentrated mode field which is promisingfor the applications of bio-or chemical-sensing, active material light emissionenhancement, and highly compact SPP-based function devices. This dissertationis theoretically and experimentally devoted to the hybrid coupling mechanism ofSRSPP in the waveguide structure as well as its application in integratedfunction devices.A novel vertical hybrid coupling structure comprised of a SRSPPwaveguide and a dielectric waveguide （DW） is proposed. Based on this hybridcoupling, the problems on the excitation, detection and application of SRSPP inintegratable devices can be solved. The simulation platform is established forboth2D and3D structure. By inducing a high-loss orthogonal normalizationtheory, the hybrid coupling effect between SRSPP and DW mode can becalculated and analyzed.The working mechanism of SRSPP-DW hybrid coupling is theoreticallyinvestigated. The dispersion curve of coupled eigenmodes as well as the wavelength andstructure parameter dependence of mode filed pattern and coupling efficiency arecalculated and analyzed for both TM and TE polarized mode. It is calculated thatSRSPP can strongly couple with DW TM mode but no couple with TE mode. Based onthe SRSPP-DW coupler, the SRSPP can be excited and detected by DW TM modetheoretically. The simulation results show that the wave vectors match between SRSPPand DW TM mode as well as the appropriate waveguide separation are the necessaryrequirements for the highly efficient coupling. In addition, the complex field ofeigenmodes results in non-zero stimulated initial phase, which causes thenon-symmetric coupling length between SRSPP and DW TM mode.The coupling performance and polarization characteristics of theSRSPP-SiNxhybrid structure are experimentally studied. By exploring theprocess flow and measurement scheme, the SRSPP-SiNxcouplers with diferentstructure parameters are fabricated and tested. It is observed that there is no coupling between SRSPP and DW TE mode but highly efficient coupling withDW TM mode, by which SRSPP is successfully excited within coupling lengthof30μm. Based on the significant difference in the coupling efficiency betweenTM and TE, a SRSPP-based high performance polarizer with TE/TM exactionratio up to30dB and TE insertion loss as low as0.17dB is realized, which isconsistent with theoretical prediction. The experimental results show that thedevice length is less than100μm, which is two-order of magnitude smaller thanconventional ones.A SRSPP-DW coupling sensor for highly sensitive refractive indexdetection of an ultra-thin analyte is proposed. The refractive indexindependence of SRSPP-DW coupling and its application on bio-sensing aretheoretically and experimentally explored. The simulation results show thateven if the detection layer is thinner than1/15wavelength, the detectionresolution can be as small as5.5×10^-6RIU, which is about10times better thanthe conventional integrated SPP sensor. Furthermore, the SRSPP-DW couplingsensor samples are fabricated. The refractive index sensing characteristic ismeasured and confirmed. It is estimated from the measurement results that therefractive index detection resolution is about1.2×10^-5RIU.