Research On Nanophotonics Devices Based On Metallic-dielectric And Photonic Crystal Structure

With the development of modern nanofabrication and nanophotonics, the study of manipulating electromagnetic wave in the nano structure and nanophotonic effection and application become a hot subject in recent years. The new nanophotonic functional devices has a good prospect in future large scale photonic integrated circuit and all optical networks because of their high compact, high integration and perfect performance features.Based on nanophotonics near-field optical theory and breaking the classical diffraction limit theory, the electromagnetic wave propagation characteristic both in metallic-dielectric single layer and multilayer slabs, single and dual grating structures, photonic crystal waveguide and nanocavity are investigated. In the nanophotonics devices field the following novel progress were gained:An ultra-narrow-band visible light absorber based on a stack of silver and alumina slabs is investigated. Due to the Fabry-Perot resonance supported in the alumina slab of the insulator-metal-insulator-metal structure and the silver’s inherent loss, an ultra-narrow-band absorption is realized in the visible region. The top insulator layer acting as a functional gain layer that can greatly enhance the injection efficiency of incident light with frequency falls into the gain bands. We discuss this problem and propose an impeccable IMIM structure that can greatly enhance the peak absorbance to95%, and the FWHM remain less than1.9%.A category of microstructure is proposed, which consists of a seamless metallic film sandwiched in multi-layer dielectric films of Si and SiO2. Such a structure can support unimaginable high broadband electromagnetic transmission from visible to near infrared. The transfer matrix theory is used to perform the numerical experiment and analyze the transmission characteristics. It has been revealed that Fabry-Perot and bulk plasmon resonant modes excited in the composite structure contribute to the high broadband transmission that is weakly dependent on the geometry parameters and the polarization and incident angle of the light. When using a15nm Ag film, the calculated structure’s sheet resistance is2Ω/sq, which is superior to that of indium tin oxide glasses, thus making promising applications in optoelectronic devices, especially in photovoltaics.Moreover we present a new mechanism to realize broadband transmission at near infrared in a dual-layer metallic-silver-grating structure. With parameters optimized, high transmittance up to85%with full-width-at-half-maximum bandwidth of64%near1.9m can be realized for TM-polarized light. And furthermore we predict an unexpected perfect optical absorption phenomenon of oblique-incident transverse magnetic polarized light in a metallic grating situated in asymmetric surroundings. The influences of structural parameters, such as grating thickness, slits material on the anomalous absorption are investigated. Based on these properties, a plasmonic absorption device with a designed absorption line shape is proposed.We demonstrate an infrared spectrometer based on a combination of line-defect waveguide and photonic crystal waveguide and nanocavity structure are fabricated on a200nm thick silicon membrane. This photonic crystal pattern having a resolution of1nm and operation bandwidth from1520to1560nm can be packaged into a microspectrometer when integrated with a two-dimensional detector array. And with substitution of membrane material and structure parameters, this design can be easily extended into the visible regime and developed for a variety of highly efficient, miniature nanophotonic applications.