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Tunable Silieon-Graphene Hybrid Nanophotonic Waveguides And Devices

Posted on:2017-01-08Degree:DoctorType:Dissertation
Country:ChinaCandidate:L H YuFull Text:PDF
GTID:1108330491462886Subject:Optical communication technology
Abstract/Summary:PDF Full Text Request
With the rapid development of the information technology, the demands are increasing for communication networks, high-speed interconnection and information processing. Silicon photonics is one of the most promising technologies to realize large-scale photonic integrated circuits (PICs), due to its ability to achieve ultracompact and low-cost devices, as well as the CMOS compatibility. It is playing a more and more important role in optical communication, optical interconnection and intelligent sensing. As the key components of PICs, tunable photonic integrated devices have been widely studied. To realize high performance active and functional devices, other materials are always introduced to silicon through hybrid integration. Graphene is a novel two-dimensional crystal material. It has attracted extensive interest due to its extraordinary electronic, photonic, mechanical and thermal properties. However, the two-dimensional structure limits its interaction with optical field, making it challenging to take advantage of the excellent photonic and optoelectronic properties. In this thesis, we focus on the hybrid integration of silicon and graphene, in order to match their advantages with the requirements. We propose and demonstrate the theoretical models, fabrication processes and applications of tunable silicon-graphene hybrid nanophotonic waveguides and devices.Firstly, we introduce the lattice structure, energy band, and optical conductivity of graphene, and describe its photonic and optoelectronic properties theoretically. We suggest two simulation methods for graphene, and demonstrate the modes and propagation losses of silicon-graphene hybrid nanophotonic waveguides with the simulation. Then, we make detailed discussions about the graphene preparation, characterization and transfer to the substrate. The fabrication and measurement methods of silicon nanophotonic waveguides are also introduced. Based on these, we develop the fabrication process for silicon-graphene hybrid integrated devices.Secondly, we fabricate and characterize the silicon-graphene hybrid nanophotonic waveguides. In these hybrid nanophotonic waveguides, we demonstrate an optically induced transparency (OIT) effect, which has an extremely low pump power density (as low as ~2 W/cm2), local and nonlocal (as far as ~4 mm) illumination responses. By ultilizing the OIT effect, silicon-graphene hybrid nanophotonic waveguides could be used to realize all-optical, broadband, remote modulation and control with low power consumption. The mechanism of the OIT effect and the characterizations of the all-optical tuning are demonstrated through experimental measurements and theoretical modeling.Thirdly, we propose a transparent graphene nanoheater and a transparent graphene heat conductor, and experimentally demonstrate some thermally tunable microdisk resonators and Mach-Zehnder interferometers. The transparent graphene nanoheater has improved performance than a metal heater in terms of the heating efficiency, temporal response and achievable temperature. It is convenient for the transparent nanoheater to be used in nanophotonic devices with nonplanar structures or in a nanoscale size. The transparent graphene heat conducor could realize nonlocal heating, which benefits from the high thermal conductivity (up to ~5300 W/m·K) of graphene. This novel heating method could be useful for surface-emitting devices and arrayed devices.Finally, we summary the thesis contents, give the prospects for the development of silicon-graphene photonic integrated devices and silicon photonics.
Keywords/Search Tags:silicon photonics, graphene, hybrid integration, all-optical tuning, thermal tuning, optically induced transparency effect, transparent graphene nanoheater, transparent graphene heat conductor
PDF Full Text Request
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