Research On The Photonic Components Based On Plasmonic Material And Silicon In Sub-wavelength Scales

Size reduction is a key issue in the development of contemporary integrated photonics. This thesis is mainly devoted to study some integrated photonic components in sub-wavelength or nanometric scales, both theoretically and experimentally. The possible approaches to reduce the sizes or to increase the functionalities of photonic components are discussed, including waveguides and devices based on silicon nanowires, photonic crystals, surface plasmons, and some near-field plasmonic components.First, some numerical methods, including the finite-difference time-domain method and the full-vectorial finite-difference mode solver, are introduced. The finite-difference time-domain method can be used to investigate the interaction of light fields with virtually arbitrary structures. The full-vectorial finite-difference mode solver is mainly used for calculating the eigenmodes of a waveguide structure.The fabrication and characterization technologies for nano-photonic components are reviewed. The fabrications are mainly based on semiconductor cleanroom facilities, which include thin film deposition, electron beam lithography, and etching. The characterization setup with the end-fire coupling is also described.Surface plasmon waveguides and devices are analyzed theoretically. With surface plasmons the light field can be confined in a true sub-wavelength dimension. Some related photonic devices, e.g., 90° bends, directional couplers, and ring resonators, are studied. We also show that some ideas and principles of microwave devices, e.g., a branch-line coupler, can be borrowed for building corresponding surface plasmon based devices. Metal-coated fiber probes are analyzed and designed. A new scheme of illumination-mode near-field scanning optical microscope has been introduced by employing a plasmon probe with the TM₀₁ mode excitation.Silicon nanowire waveguides and related devices are studied. Arrayed waveguide gratings with 11 nm and 1.6 nm channel spacing are fabricated and characterized. A more compact design with the overlapped free propagation regions has beenemployed for these arrayed waveguide gratings. Etched diffraction gratings are also designed and fabricated. The typical dimension of these devices are several hundred micron, which is 1 — 2 order of magnitude smaller than conventional silica based ones. Various planar photonic crystal waveguides are analyzed and characterized. A compact polarization beam splitter employing positive/negative refraction based on a photonic crystal of silicon pillars is designed and demonstrated. Extinction ratio of ～15 dB is achieved experimentally in a wide wavelength range.