The Electro Optical Modulation Technology Based On Graphene And Silicon Nanometer Waveguide Hybrid Structure

As the information industry develops, it is more and more challenging for the technology improving of the information calculation and transmission to deal with the increasing enormous amount of data. Comparing with the electrical signal, optical signal has many advantages such as much larger data capacity, faster transmission speed and the strong antijamming capability. In order to meet the demand of the large data capacity, fast processing speed and low loss, it is desiderative to use the optical chip to overcome the electronic bottleneck abided by Moore's law. The silicon nanometer optical waveguide is a structure that guides light in sub-wavelength scale and it can realize the light information transmission, coupling and interaction with materials. It is the base units of the optical source, sensing part and modulators that integrated on an optical chip.Graphene, a new two dimensional structure, has become a promising electro optical material due to its linear dispersion band structure, high carrier mobility and electrical tunable Fermi level. However, one of the greatest challenge to apply graphene to the efficient photoelectric transformation device is how to enhance the weak light absorption of a monolayer. This can be overcome by integrating graphene with an optical waveguide, which greatly increases the interaction length through the coupling between the evanescent waves and graphene. This combination can not only enhance the interaction between graphene and light, but also control the transmitting light in the waveguide and it has important research significance and application prospect in modulators and photodetectors that serve the optical chip.On the basis of the newest research achievements in the world and center on the integrating of graphene and nanometer waveguide, this thesis has carried out the research on the electro optical modulation properties based on graphene and silicon nanometer waveguide. We analyzed the properties of the graphene-silicon hybrid material and fabricated the graphenesilicon waveguide integrating circuit and finished the experimental testing and the results analysis. In this thesis, we fabricated the double-layer-graphene capacitor integrated with the silicon ring resonator and improved the modulation efficiency utilized the irregular cavity for the first time. Furthermore, we put forward an idea that use graphene to control the optical analog to electromagnetically induced transparency in cascaded silicon ring system for the first time to our knowledge. The related research contents can be conclude as below:1. We theoretically analyzed the optical transmission properties and the single-mode transmission condition of the optical waveguide. By simulating and optimizing the parameters of the grating waveguide we improved the coupling efficiency of the grating. We theoretically analyzed the transmision properties of resonator, which is the key element of the optic waveguide device. At last, we designed the layout of the optimized optic wavguide with L-edit. The grating and the resonators were fabricated with the technology of electron beam lithography and the inductively coupled plasma etching. The fabricated device was tested a Q factor of 105 were achieved.2. The properties of the graphene sheet was analyzed and the relationships between the applied voltage and Fermi level and the dielectric constant were simulated. The monolayer graphene was grow on the copper by Chemical Vapor Deposition and transferred into the silicon waveguide by wetting transfer method. We solved many difficulties exist in the fabrication of the graphene-silicon waveguide integrating chip and finished the fabrication using the electron beam evaporation, atomic layer deposition and ultra-violet lithography and finished the encapsulation and bonding with PCB and finally achieved graphene-waveguide chip.3. We tested the modulation properties of the graphene-resonator hybrid structure and designed the irregular resonator to enhance the interaction between graphene and the light. A great modulation depth of 26 dB has been achieved and the result has been further analyzed. The on-chip analog to electromagnetically induced transparency has been observed and we applied the Fermi level tunable property of graphene in this effect. The experimental realization of tunable analog to electromagnetically induced transparency has been achieved and the red shift and blue shift of the curve have been analyzed in detail.