Basic Research On Graphene Optical Modulator

With the fast development of optical communication network, the traditional optical modulator has been difficult to satisfy the trend of its development, it’s time to find a new optical modulator with ultra-high modulation rate and wide bandwidth.Graphene due to its unique electronic and optical properties, has attracted great attention throughout the researchers all of the world. Compared with the traditional optical modulator, graphene optical modulator has some merits such as ultra-high modulation rate, high extinction ratio and small size.In this thesis, the graphene optical modulator is studied and the working principle of all kinds of graphene optical modulator is introduced. A multilayer graphene optical modulator model and a graphene polarization-insensitive electro-optic modulator model are proposed and simulation analysis is carried on. The main work of this thesis includes four aspects:1. The development of the optical communication is introduced. All kinds of the traditional optical modulator and their advantages and disadvantages are introduced.The research progress, the structure and the parameters of the graphene optical modulator are introduced.2. The structure of the graphene and its physical properties are introduced, and the formula for optical properties of the graphene is derived. In this thesis the working principle of all kinds of graphene optical modulator are introduced in detail.3. In this thesis, a multilayer graphene optical modulator is proposed and the simulation analysis is carried on. The results of simulation show that the attenuation constant of TE mode and TM mode will be increased with the increasing of the graphene layers. Since the TM mode of four layers graphene optical modulator is similar to five layers graphene optical modulator, four layers graphene optical modulator is chosen because of the fabrication technology problem. In the simulation,the slot effect is observed, and the advantages of slot effect are introduced. Then the parameters of four layers graphene optical modulator are optimized, the results of simulation show that the best choice is the middle waveguide is 0.1 ?m, the refractive index of spacer is 1.98. When the active region is 5 ?m, the modulation bandwidth is about 100 GHz and the power consumption is about 19 bitf J /.4. In this thesis, a polarization insensitive graphene optical modulator is proposed and the simulation analysis is carried on. The results of simulation show that while the inclination angle of this modulator is 52 °, the waveguide height is 0.38 ?m, the waveguide width is 0.5 ?m, the spacer thickness is 10 nm, the spacer width is 0.35 ?m,its polarization insensitive is best. The attenuation constant curves of TE mode and TM mode are almost consistent with the change of the chemical potential, which make the modulator polarization insensitive. When the active region is 5 ?m, the modulation bandwidth is about 160 GHz and the power consumption is about 12 bitf J /.