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Research On Four-wave Mixing Differency Frequency Generation Of Terahertz Radiation And The Properties Of Photonic Crystal Fibers

Posted on:2013-02-02Degree:MasterType:Thesis
Country:ChinaCandidate:S H ZhangFull Text:PDF
GTID:2218330362961602Subject:Photonics technology
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Due to the special position of terahertz frequency between electron and photon frequency, it displays great potential applications in those areas such as spectrum analysis, medical imaging, environmental monitoring, communication and national defense and can find favor in researchers eyes. Four-wave mixing difference-frequency generation of terahertz radiation based on the nonlinear optical frequency conversion technology has numerous advantages, such as operating at room temperature, high peak power, widely tunable ranges and compactness. Given the unique structure and design flexibility of photonic crystal fibers, we focus on analysis of the nonlinear coefficient properties, and study the feasibility of generation terahertz waves in photonic crystal fiber. The main content and creative points in the dissertation as follows:1. The important features of terahertz radiation, optical methods of its generation and its applications are viewed. In addition, basic concepts, classification and related features of photonic crystal fiber are briefly summarized.2. The program of using GaSe crystal and alkali metal vapor to generate terahertz radiation based on four-wave difference frequency mixing effects are theoretically proposed, and then starting from the nonlinear coupled wave equations, we do theoretical analysis on the four-wave difference frequency mixing process, obtain the analytical expressions of the terahertz output power, as well as the phase matching conditions. By adjusting the pump frequency, the third-order nonlinear polarization of alkali metal vapor has been resonance-enhanced. In the experiment, a dual-wavelength output is realized operating around the degenerated point of 2.12 m, based on noncritically phase-matched KTP OPO pumped by a internal electro-optically Q-switched 1.064μm pulsed Nd:YAG lasers in a compound cavity configuration.3. First, various methods of simulation of photonic crystal fiber are outlined, highlighting the basic principles of finite element method; then the software COMSOL Multiphysics based on finite element is briefly described, and the specific steps of modeling and simulation are given.4. The numerical simulation of photonic crystal fiber dispersion and nonlinear properties is introduced, and then we design two types of fiber structures which can realize ultra-flattened zero dispersion and high nonlinearity. The numerical simulation are done using the software COMSOL based on full-vector finite element methods.5. The basic principles of birefringence, implementations of high birefringence photonic crystal fiber and the current research are introduced, and the numerical simulation method of photonic crystal fiber birefringence is proposed. Then two possible structures to achieve high birefringence are presented and can be applied in optical sensing and communication systems as well as many other areas.
Keywords/Search Tags:nonlinear optics, four-wave mixing difference frequency, terahertz radiation, photonic crystal fiber
PDF Full Text Request
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