Based On The Study Of The Theory Of The Optical Methods Generate Terahertz Radiation

As the last one electromagnetic band been studied in the electromagnetic spectrum, people are optimistic about the application of terahertz radiation, even it is known as "one of the world’s top ten technologies which changes the future". Now, the researches about terahertz radiation are on the terahertz radiation source, the terahertz detection and terahertz military applications. The terahertz radiation source is the basis of the terahertz radiation applications.This dissertation mainly studies two terahertz radiation generations based on the optical methods. One is the terahertz optical rectification, and the other is the excitation of large-aperture photoconductive antenna to generate terahertz radiation by the use of ultrashort laser pulses. It analyzes the relevant factors which affect the generation of terahertz radiation. The main results are as follows:1. It researches terahertz optical rectification, point out the impact of the phase matching to this process and how to achieve phase matching. Combining with the simulation study on refractive index and coherence length about three nonlinear crystals, it provides a guideline for us to choose the crystal and pump source. Finally, the research analyzed the impact of phase mismatch and attract to the conversion efficiency under different conditions.2. After considering the thickness of the photoconductive material, on the basis of the theoretical studies, it establishes a new large-aperture photoconductive antenna radiation terahertz theoretical model. On this basis, we carry out the study of number simulation and analysis the influential factors about the generation of terahertz radiation. Finally, the dissertation carries out a comparative analysis about the far-field time-domain waveform under the conditions considering the thickness of the photoconductive material or not considering the thickness.This dissertation analyzes the two methods used usually to produce terahertz radiation based on optical method, we know all impacts of various factors well, and it provides a great help for us to improve the generated terahertz radiation power.