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The Research Of Theory About Graphene To Generate THz Wave And Waveguide Device

Posted on:2013-05-19Degree:MasterType:Thesis
Country:ChinaCandidate:W P WangFull Text:PDF
GTID:2268330392969929Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
In recent years, with the speedy development of semiconductor-microelectronic technology, super fast laser technology and nonlinear optical frequency conversion technology, THz wave technology in relation to the THz radiation and THz waveguide gradually become a hot topic of in research field all over the world. As a key point of the THz research, it is all the time for every scientist to develop a high-power, high-efficiency, working at room temperature and tunable radiation source. On the other hand, THz waveguide with the low-loss, broadband and long distance transmission is still the the focus of research all around the world.As a novel material, graphene has lots of properties that other material can not be matched. The Plasma oscillation, external controlled conductivity and tunable energy gap of graphene are all relation to the THz technology. Graphene has the features of negative conductivity in the THz frequency band due to the gapless linear level structure of electrons and holes and it also has the electronic and optical property to act as the THz wave generation and amplification material. Its unique generating method provides the possibility of stable and high-power THz source. We can also develop the low-loss and broadband THz waveguide by designing the structure and size.We mainly calculate and analysis the theory of THz generation by using graphene. We also design a THz waveguide by doping the monolayer graphene and discuss its transmission property and parameters. The main content and innovation points we will talk about in this paper are as follows:1. Summarize the photonics and electronics methods of THz generation, THz application and developing situation. Introduce the Production method of graphene and the energy structure and electron property.2. We analyze the principle of epitaxial growth method of graphene and the THz generation process emphatically, including the recombination mechanism of photo-induced carrier, the model and method to generate THz wave, the relationship of negative conductivity and and THz generation so on.3. Study the the theory of negative conductivity about graphene and analyze the influence of graphene conductivity about effective temperature, carrier density, phonon scattering time, electron-hole recombination time. The effect of interband transition becomes stronger with the pumping intensity, and it results in the negative conductivity. What’s more, the curve drifts to the negative part because of the increasing effective temperature, we can obtain more smooth and wide range cures through increasing it. We achieve the lowest conductivity about-5x10-5S/m in the range that is larger than2THz.4. Design a new low-loss THz waveguide structure and elaborate the basic Theory of cylinder THz waveguide. Use the FEM method to calculate and simulate the relationship of transmission mode LPoiand LP11, and acquire the critical radii about high-quality transmission. We calculate the loss coefficient of fundamental mode when frequency is larger than2THz is a≈0.55dB/m. It lays the theoretical foundation for the THz waveguide with the properties of long distance and wide frequency.
Keywords/Search Tags:THz source, graphene, negative conductivity, THz waveguide
PDF Full Text Request
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