飛秒雷射脈衝量測與形變之研究

Abstract

在此篇碩士論文中，我們初步研究建立了以頻率解析光閘量測系統為基礎的脈衝形變系統。我們利用LabVIEW程式，建立了全LabVIEW控制及Singular Value Decomposition相位重建演算法的頻率解析光閘，以此來量測飛秒脈衝雷射，獲得脈衝電場振幅及相位。並以此量測系統來量測通過脈衝形變系統之脈衝，以期建立一套脈衝形變系統。 另外，我們以模擬退火演算法及富立葉轉換演算法計算脈衝形變之相位調制，獲得多種形式脈衝波形相位調制的模擬結果。在脈衝形變系統中，我們以鈦藍寶石雷射作為光源、1800 line/mm的光柵及15公分的透鏡作為形變系統、向列型液晶元件作為空間光調制器來調制脈衝的頻譜。我們另外模擬了模擬脈衝振幅調制之結果，實驗所獲得的結果與模擬所得有所差異，推測是因為未加液晶空間光調制器前的脈衝形變系統的啾頻效應沒有補償造成。

In this thesis, we preliminary try to build up a pulse shaping system based on Frequency Resolved Optical Gating (FROG) system. LabVIEW program is used to set up the FROG system totally LabVIEW controlled and Singular Value Decomposition phase retrieval algorithm. The field amplitude and phase can be obtained from femtosecond laser pulse measured by the system. And we expect to set up a pulse shaping system by measuring the shaped pulse and getting the electric field amplitude and phase. In addition, we calculate the phase modulation of pulse shaping by simulated annealing algorithm and Fourier transform algorithm, so lots of phase modulation simulated results of many types of pulse are obtained. In our pulse shaping system, we use the Ti-sapphire laser as source, grating of 1800 line/mm and lens of focal length 15 cm as pulse shaping apparatus, and twist-nematic liquid crystal as spatial light modulator to modulate the pulse spectrum. And we simulate the amplitude modulation, though the simulated results are different with that acquired in this experiment, this is probably due to that the chirp caused by the shaping system without LC SLM is not compensated.