【摘要】：紫外激光具有波長短,易聚焦,分辨率高,光子能量大等特點(diǎn)而被廣泛應(yīng)用于激光雷達(dá)、激光通訊、激光標(biāo)記和生物分子機(jī)制研究等方面。盡管LD(LaserDiode)泵浦的固體紫外激光器已經(jīng)出現(xiàn)了一些實(shí)用化的裝置,但是在實(shí)際中還面臨光束質(zhì)量較差,激光器功率穩(wěn)定性不足,通過水冷控制溫度導(dǎo)致激光器體積較大,使用不方便等問題。本論文旨在改善紫外激光器的穩(wěn)定性,減小激光器體積,改善光束質(zhì)量,同時(shí)提高可靠性和使用壽命,使激光器能夠滿足實(shí)用化要求,具體工作如下：(1)對LD泵浦調(diào)Q激光器進(jìn)行了分析,由調(diào)Q原理結(jié)合四能級(jí)速率方程推得調(diào)Q激光器速率方程。同時(shí)根據(jù)三波互作用的耦合波方程,對頻率轉(zhuǎn)換等非線性過程、效率以及相位匹配過程進(jìn)行了理論分析。(2)采用LD端面泵浦Nd:YVO4晶體產(chǎn)生基頻光,LiB3O5 (LBO)晶體進(jìn)行倍頻與和頻,聲光調(diào)Q產(chǎn)生巨脈沖,比例積分微分算法(PID, Proportion Integration Differentiation)控制精確溫度調(diào)節(jié),補(bǔ)償非線性晶體角度相位匹配誤差,實(shí)現(xiàn)了一臺(tái)輸出波長為355nm的小型紫外激光器。該激光器在重復(fù)頻率為15kHz,泵浦功率為13.33W時(shí),355nm激光平均輸出功率為1.24W,808nm-355nm的轉(zhuǎn)換效率為9.3%,輸出激光脈沖寬度為9.8ns,光束質(zhì)量因子Mx2和My2分別為1.8和1.7,該激光器2小時(shí)內(nèi)輸出功率不穩(wěn)定度為0.45%。(3)采用LD端面泵浦Nd:YVO4晶體產(chǎn)生基頻光,LBO晶體進(jìn)行倍頻,BaB2O4 (BBO)晶體進(jìn)行四倍頻,聲光調(diào)Q產(chǎn)生巨脈沖,實(shí)現(xiàn)了輸出波長為266nm的激光器。該激光器在重復(fù)頻率為15kHz,泵浦功率為12.58W時(shí),266nm平均功率為440m W,脈沖寬度為10.7ns。該激光器采用多鏡腔結(jié)構(gòu),通過多次反射倍頻激光與四倍頻激光,補(bǔ)償由于BBO晶體走離效應(yīng)產(chǎn)生的光斑不均勻性,使出射光斑接近圓斑。(4)采用LD端面泵浦Nd:YAG晶體,LBO晶體進(jìn)行倍頻,KD2PO4 (DKDP)晶體進(jìn)行四倍頻,Cr4+:YAG晶體調(diào)Q產(chǎn)生巨脈沖,實(shí)現(xiàn)了輸出波長為266nm的激光器。實(shí)驗(yàn)中采用的DKDP晶體尺寸為10×10×20mm3,氘元素含量為98%,非線性過程采用Ⅰ類溫度相位匹配方法。該激光器在重復(fù)頻率為10Hz,泵浦功率為60W,泵浦脈寬為500μs時(shí),獲得266nm激光輸出能量為57μJ、266nm激光脈沖寬度為亞納秒量級(jí)。
[Abstract]:Ultraviolet laser has been widely used in lidar, laser communication, laser labeling and biomolecule mechanism because of its long wave length, easy focusing, high resolution and large photonic energy. Although some practical devices have appeared in the solid-state ultraviolet laser pumped by LD (LaserDiode), in practice, the beam quality is poor, the power stability of the laser is insufficient, and the volume of the laser is larger due to the control of temperature by water cooling. It is inconvenient to use and so on. The purpose of this paper is to improve the stability of ultraviolet laser, reduce the volume of laser, improve the beam quality, and improve the reliability and service life, so that the laser can meet the practical requirements. The specific work is as follows: (1) the LD pumped Q-switched laser is analyzed, and the rate equation of Q-switched laser is derived from the Q-switching principle combined with the four-level rate equation. At the same time, according to the coupling wave equation of three-wave interaction, the nonlinear processes, such as frequency conversion, efficiency and phase matching process are analyzed theoretically. (2) the fundamental frequency light is generated by LD end-pumped Nd:YVO4 crystal. The frequency doubling and sum frequency of LiB3O5 (LBO) crystal is carried out, and the giant pulse is generated by acousto-optic Q-switching. The proportional integral differential algorithm (PID, Proportion Integration Differentiation) controls the accurate temperature adjustment and compensates the angle and phase matching error of nonlinear crystal. A small ultraviolet laser with output wavelength of 355nm is realized. When the repetition rate is 15kHz and the pump power is 13.33W, the average output power of 355nm laser is 1.24W, the conversion efficiency of 808nm 鈮，

本文編號(hào)：2479546