【作者】 张健；

【导师】 李述涛； 于永吉；

【作者基本信息】 长春理工大学 ， 物理学、光学， 2017， 硕士

【摘要】 2.1μm波段激光器在激光医疗、激光雷达、光电对抗等领域都有着广泛的应用,线宽窄化、功率提高是应用需求驱使下2.1μm激光器极为重要的发展方向,具有广阔的发展前景。基于MgO:PPLN准相位匹配技术的光参量振荡器是获得2.1μm激光的有效方法,但该方法受变频简并点、泵浦光线宽和强抽运下的高增益等影响,输出的2.1μm激光线宽较宽,针对这一问题,本论文开展了相关理论和实验研究。理论方面研究了MgO:PPLN晶体调谐特性,基于MgO:PPLN的2.1μm单谐振光参量振荡器增益、阈值及转换效率,优化设计了1.064μm高重频泵浦源及光参量振荡器器件参数。分析了造成2.1μm激光中心波长漂移及线宽展宽的原因,理论计算了2.1μm激光线宽展宽量,并且在此基础上,在保证光谱选择性的前提下,研究了体布拉格光栅器件不同光栅厚度d,光栅的空间频率f和折率调制量δn等参数对线宽窄化的影响。实验方面MgO:PPLN晶体温度固定在50.5°C,采用折叠型外腔泵浦结构,1064nm泵浦功率为12.9W条件下,自由运转时实现了5.51W的简并波长2.1μm激光输出,光谱线宽为109nm,引入VBG光栅器件,获得2.904W窄线宽2.1μm激光输出,线宽被有效压窄至0.17 nm,光-光转换效率达到22.5%。更多还原

【Abstract】 2.1μm laser has been widely used in laser medicine,laser radar and optoelectronic countermeasure.Narrow width and high Power which is needed for application are important developing direction with broad prospects for development.Optical parametric oscillator with quasi phase matching technique based on MgO:PPLN is the effective way to obtain 2.1μm laser.However,this way was influenced by Frequency degenerate point,line width of pumped light and high gain of strong pumping,which cause line width of 2.1μm laser broadening.For this problem,relative theory and experiments were researched in this paper.In theory,tunable characteristics of MgO:PPLN crystal was studied.Based on gain,threshold and conversion efficiency of 2.1μm single tuning optical parametric oscillator of MgO:PPLN,1.064μm high repetition pumping source and elements parameters of optical parametric oscillator were designed with optimum.The reasons of center wavelength shifting and line width broadening of 2.1μm laser were analyzed and broadening value of 2.1μm laser line width was calculated in theory.According to these basis,by studying the parameters of grating thickness,d,spatial frequency of the grating,f,and modulation amplitude of the refractive index,δn,the influence of line width narrowing was analyzed on the premise of spectral selectivity.In experiments,2.1μm degenerate laser output power of 5.51 W was obtained in free operation with folding type external cavity pump structure,which the power of 1064 nm laser was 12.9 W and the temperature of MgO:PPLN crystal was fixed at 50.5°C.The line width of laser was 109 nm.2.904 W of 2.1μm laser output of narrow line width was achieved with optical conversion efficiency of 22.5% for injecting VBG grating elements,which laser line width was effectively narrowed to 0.17 nm.更多还原