Optical interconnects based on CMOS compatible photonic integrated circuits are regarded as a promising technique to tackle the issues traditional electronics faces, such as limited bandwidth, latency, vast energy consumption and so on. In recent years, plasmonic integrated components have gained great attentions due to the properties of nano-scale confinement, which may potentially bridge the size mismatch between photonic and electronic circuits. Based on silicon nanowire platform, this thesis work studies the design, fabrication and characterization of several integrated plasmonic components, aiming to combine the benefits of Si and plasmonics. The basic theories of surface plasmon polaritons are introduced in the beginning, where we explain the physics behind the diffraction-free confinement. Numerical methods frequently used in the thesis including finite-difference time-domain method and finite-element method are then reviewed. We summarize the device fabrication techniques such as film depositions, e-beam lithography and inductively coupled plasma etching as well as characterization methods, such as direct measurement method, butt coupling, grating coupling etc. Fabrication results of an optically tunable silicon-on-insulator microdisk and III-V cavities in applications as light sources for future nanophotonics interconnects are briefly discussed. Afterwards we present in details the experimental demonstrations and novel design of plasmonic components. Hybrid plasmonic waveguides and directional couplers with various splitting ratios are firstly experimentally demonstrated. The coupling length of two 170 nm wide waveguides with a separation of 140 nm is only 1.55 µm. Secondly, an ultracompact polarization beam splitter with a footprint of 2×5.1 μm2 is proposed. The device features an extinction ratio of 12 dB and an insertion loss below 1.5 dB in the entire C-band. Thirdly, we show that plasmonics offer decreased bending losses and enhanced Purcell factor for submicron bends. Novel hybrid plasmonic disk, ring and donut resonators with radii of ~ 0.5 μm and 1 μm are experimentally demonstrated for the first time. The Q-factor of disks with 0.5 μm radii are                         , corresponding to Purcell factors of . Thermal tuning is also presented. Fourthly, we propose a design of electro-optic polymer modulator based on plasmonic microring. The figure of merit characterizing modulation efficiency is 6 times better comparing with corresponding silicon slot polymer modulator. The device exhibits an insertion loss below 1 dB and a power consumption of 5 fJ/bit at 100 GHz. At last, we propose a tightly-confined waveguide and show that the radius of disk resonators based on the proposed waveguide can be shrunk below 60 nm, which may be used to pursue a strong light-matter interaction. The presented here novel components confirm that hybrid plasmonic structures can play an important role in future inter- and intra-core computer communication systems. / <p>QC 20140404</p>

Nowadays, silicon photonics is a widely studied research topic. Its high-index-contrast and compatibility with the complementary metal-oxide-semiconductor technology make it a promising platform for low cost high density integration. Several general problems have been brought up, including the lack of silicon active devices, the difficulty of light coupling, the polarization dependence, etc. This thesis aims to give new attempts to novel solutions for some of these problems. Both theoretical modeling and experimental work have been done. Several numerical methods are reviewed first. The semi-vectorial finite-difference mode solver in cylindrical coordinate system is developed and it is mainly used for calculating the eigenmodes of the waveguide structures employed in this thesis. The finite-difference time-domain method and beam propagation method are also used to analyze the light propagation in complex structures. The fabrication and characterization technologies are studied. The fabrication is mainly based on clean room facilities, including plasma assisted film deposition, electron beam lithography and dry etching. The vertical coupling system is mainly used for characterization in this thesis. Compared with conventional butt-coupling system, it can provide much higher coupling efficiency and larger alignment tolerance. Two novel couplers related to silicon photonic wires are studied. In order to improve the coupling efficiency of a grating coupler, a nonuniform grating is theoretically designed to maximize the overlap between the radiated light profile and the optical fiber mode. Over 60% coupling efficiency is obtained experimentally. Another coupler facilitating the light coupling between silicon photonic wires and slot waveguides is demonstrated, both theoretically and experimentally. Almost lossless coupling is achieved in experiments. Two approaches are studied to realize polarization insensitive devices based on silicon photonic wires. The first one is the use of a sandwich waveguide structure to eliminate the polarization dependent wavelength of a microring resonator. By optimizing the multilayer structure, we successfully eliminate the large birefringence in an ultrasmall ring resonator. Another approach is to use polarization diversity scheme. Two key components of the scheme are studied. An efficient polarization beam splitter based on a one-dimensional grating coupler is theoretically designed and experimentally demonstrated. This polarization beam splitter can also serve as an efficient light coupler between silicon-on-insulator waveguides and optical fibers. Over 50% coupling efficiency for both polarizations and -20dB extinction ratio between them are experimentally obtained. A compact polarization rotator based on silicon photonic wire is theoretically analyzed. 100% polarization conversion is achievable and the fabrication tolerance is relatively large by using a compensation method. A novel integration platform based on nano-epitaxial lateral overgrowth technology is investigated to realize monolithic integration of III-V materials on silicon. A silica mask is used to block the threading dislocations from the InP seed layer on silicon. Technologies such as hydride vapor phase epitaxy and chemical-mechanical polishing are developed. A thin dislocation free InP layer on silicon is obtained experimentally. / QC20100705