Research On Terahertz Dynamic Generation From Nonlinear Crystal Based On Optical Rectification

Terahertz (THz) technology now is widely used in many areas as astronomy,communications, biology and security screening, due to its excellent properties.However, the applications of THz radiation are still in laboratory, restricted by lowoutput power of THz sources. So the key to THz applications is how to increase theoutput power. This thesis focuses on how to enhance the THz generation power basedon optical rectification, and the contents are divided into four parts:In the first chapter, the current status of THz science and technology is reviewed,including its history, generation, application and some recent results on high-powerTHz wave generation.Next, the theory of THz wave generation from nonlinear crystals based onoptical rectification is introduced. The wave equation, phase matching condition andgeneration efficiency are derived in detail. The factors that affect THz generationefficiency are analyzed.In chapter3, a mode of THz generation dynamics based on optical rectification isestablished, by considering the effect of group velocity dispersion in nonlinearcrystals. The relationships between chirp properties of pump pulses and THzgeneration are theoretically discussed and investigated in experiments.Finally, by optimizing the chirp parameters of pump pulses, high-power THzwave of0.3mW was generated from a GaP crystal, pumped by a home-madefemtosecond photonic crystal fiber amplifier, and spectral information of the radiationwas analyzed by THz time-domain spectroscopy.