The Researches On The Characteristics And Applications Of Plasmon Hybrid Devices Based On The Grating Structure

In recent years, the surface plasmon devices have become an important research direction and hotspot in the academic research. They have a good prospect for the applications to the light-field modulating, biosensing, optical buffer and so forth. The most conventional methods available for exciting surface plasmon, including prism coupling, waveguide coupling and near-field excitation have a lot of deficiency, which hinder its development and applications in the field of optics. While the grating coupling method is becoming a better choice for plasmon hybrid devices due to its advantages of smaller, easier integration, etc. In this thesis, based on the plasmon theory and FDTD simulation method, we have investigated the relevant characteristics and applications of the grating-based plasmon hybrid devices. The research contents can be concluded as follows:(1) A spatial and spectral selective plasmonic sensing based on the metal grating arrays has been proposed and investigated theoretically. By properly tuning the geometric parameters of metal grating arrays, the enhanced optical fields at different regions can be obtained selectively due to the excitation of corresponding plasmonic mode. Simulation results show that the resonances of the metal grating arrays at different spatial locations and different wavelengths can be achieved simultaneously. A relative bigger red-shift of 57nm can be realized when a layer of biomolecular film is adsorbing at the slit walls, and the corresponding total intensity difference will be enhanced near 10 times compared to that at the top surface. In addition, when a BSA protein monolayer is adsorbing at slit walls with different slit widths, the corresponding wavelength shifts can reach to more than 80nm by modulating the widths of the slit. The simulated results demonstrate that our designed structure can serve as a biosensing with a high spatial and spectral selective performance.(2) A high-efficiency refractive index sensor based on the gain-assisted metallic grating arrays have been designed. We find that the intrinsic Ohmic loss of system hinders the improvement of the EOT efficiency of the grating array. To compensate for the intrinsic loss,we propose a method by embedding the structure in the gain-assisted medium. When the gain efficiency reaches to its corresponding threshold, the FOM* (for resonance wavelength ?2) can reach to 39100. The gain-assisted grating structure with the ultrahigh sensitivity to the RI changes of surrounding medium will be found broad applications in biomedical and environmental sensing.(3) A novel graphene plasmon system have been proposed based on dielectric grating. We have systematically investigated the trapping effect and the optical performance of SPPs on the graphene-based graded grating structure. The theoretical and numerically simulated results demonstrate that the SPPs at different frequencies within a broadband range can be trapped at different positions on the graphene surface, which can be used as a broadband spectrometer. Based on the theoretical analyses, we have predicted the trapping positions and corresponding group velocities of the SPP waves with different frequencies. By appropriately tuning the gate voltages, the trapped SPP waves can be released to propagate along the surface of graphene or out of the graded grating zone. So we have investigated the switching characteristics of the slow light system, where the optical switching can be controlled as "off" or "on" mode by adjusting the gate voltage actively.