Electromagnetically Induced Transparency-like Transmission And The Study Of Its Physic Mechanism In Two Dimension Waveguide Structures

Surface plasmon polaritons (SPPs) are waves trapped on the surfaces of metals owing to the interaction between the free electrons in metal and electromagnetic field in dielectric. Due to the capability of confining light beyond the diffraction limit and manipulation of light in nanoscale domain, SPPs can be utilized to design new types of optical device such as nanoscale optical switching, plasmonic sensing, and optical devices in highly integrated optical circuits, which have broad potentials in subwavelength optics, data storage, light generation, microscopy and bio-photonics.The main work is listed below:1. Based on Fabry-perot model and finite-different time-domain (FDTD) method, the plasmonic structure composed of a Metal-Insulator-Metal (MIM) bus waveguide and a side-coupled resonator is investigated. It is found that the transmission features can be regulated by the cavity width and coupling distance. Electromagnetically induced transparency (EIT)-like transmission can be excited by adding an identical resonator on the pre-existing structure. Combining the foregoing theoretical analysis with coupled mode theory (CMT), the formation process of the EIT-like transmission are detailedly analyzed. EIT-like transmission can also be excited in plasmonic structure with two detuned resonators. By altering the structure parameters, the transparency window can be purposefully modulated.2. An optical effect analogous to electromagnetically induced transparency(EIT) transmission in metal-insulator-metal bus waveguide is investigated, which side-coupled by two detuned aperture-resonators. Based on the coupled mode theory (CMT) and finite-difference time-domain method, the formation and evolution mechanism of EIT-like transmission by indirect coupling are exactly analyzed, from which it can be concluded that the formation of transparency window is attributed to the resonator’s length detuning and the evolution of transparency is mainly determined by the variation of coupling distance. For the indirect coupling, the group index of up to100can be obtained in the transparency window. The EIT-like transmission with direct and indirect couplings is also studied. With the merits of specific configuration in our plasmonic structure, we qualitatively describe the function of direct coupling on EIT-like transmission.3. Based on the results in the last chapter, a specific multi-cavity side-coupled structure is proposed to further study the effect of direct coupling on the transmission characteristics. Specific structure parameters are set to guarantee the indirect coupling to be unchanged. With the merits of this, the function of direct coupling is qualitatively described. Simulation results show that the shift of transmission dip can be attributed to the direct coupling and which is obvious with the enhancement of direct coupling.