直接泵浦1.5μm内腔式固体拉曼激光运转特性研究

发布时间：2018-06-21 16:13

本文选题：直接泵浦 + 固体拉曼激光器　；参考：《哈尔滨工业大学》2015年硕士论文

【摘要】：全固体拉曼激光器是目前LD泵浦固体激光器及非线性光学领域的研究热点。全固体拉曼激光器利用受激拉曼散射(Stimulated Raman Scattering,SRS)效应,结合不同波长的基频光和不同拉曼频移介质,可得到光谱范围从紫外到近红外的激光输出。与其他非线性光学频率变换技术相比,固体拉曼激光器具有无需相位匹配、脉宽窄、光束质量好等优点,并可用于实现1.5μm人眼安全波段的激光输出。本文从理论及实验两方面,对880nm LD直接泵浦的1.5μm内腔固体激光器进行了深入系统的研究。理论方面:利用非线性光学耦合波方程以及经典谐振子模型,推导了稳态和瞬态情况下斯托克斯散射光场的增益表达式,并结合实际测量参数理论计算了不同波长下增益系数大小。采用主动调Q拉曼激光器速率方程理论,结合四阶龙格-库塔法,数值模拟了反转粒子数和腔内光子数随时间的变化情况,讨论了拉曼激光脉冲的的建立和消减过程。根据矩阵光学理论,利用MATLAB软件模拟计算了不同谐振腔结构下,基频光光斑半径和稳定性因子随腔长的变化以及腔内不同位置处的光斑大小。模拟分析了不同泵浦水平下激光晶体以和拉曼晶体的热透镜效应及其对拉曼激光的影响。实验方面:通过880nm LD直接泵浦方式端面抽运Nd:YVO4晶体,获得了1342nm基频光的有效振荡,并利用YVO4晶体的一阶Stokes效应,实现了从1342nm到1525nm的拉曼频移激光输出。采用三种不同腔型结构,研究了泵浦功率和脉冲重复频率对1525nm拉曼激光的平均功率、脉冲宽度和波形、输出光束质量等参数的影响。在15.9W的LD泵浦功率及30k Hz的重复频率下,最高获得530m W的平均功率输出。在脉冲重复频率为10k Hz时,得到LD泵浦阈值的最低值为2.6W,并当LD泵浦功率大于9.1W时,1.5μm拉曼激光脉冲宽度稳定在5ns左右,与基频光脉冲相比,得到了有效压缩。
[Abstract]:All-solid-state Raman lasers are currently the focus of LD pumped solid-state lasers and nonlinear optics. Using stimulated Raman scattering Raman scattering (SRS) effect, combined with different wavelength of fundamental frequency light and different Raman frequency shift medium, the laser output from ultraviolet to near infrared can be obtained by all-solid-state Raman laser. Compared with other nonlinear optical frequency conversion techniques, solid-state Raman lasers have the advantages of no phase matching, narrow pulse width and good beam quality, and can be used to achieve 1.5 渭 m human eye safe wavelength laser output. In this paper, a 1.5 渭 m intracavity solid-state laser pumped directly by 880nm LD is studied systematically and theoretically. Theoretically, the gain expressions of Stokes scattering light field under steady and transient conditions are derived by using nonlinear optical coupling wave equation and classical harmonic oscillator model. The gain coefficient at different wavelengths is calculated with the theory of actual measurement parameters. Based on the rate equation theory of active Q-switched Raman laser and the fourth-order Runge-Kutta method, the changes of the number of inversion particles and the number of photons in the cavity with time are numerically simulated, and the establishment and subtraction of Raman laser pulses are discussed. According to the theory of matrix optics, the variation of the radius and stability factor of the fundamental frequency light spot with the cavity length and the size of the spot at different positions within the cavity under different resonator structures are simulated by using MATLAB software. The thermal lens effect of laser crystal and Raman crystal and its influence on Raman laser are simulated and analyzed at different pumping levels. Experimental results show that ND: YVO4 crystal is pumped by 880nm LD directly, and the effective oscillation of 1342nm fundamental frequency light is obtained. The Raman frequency shift laser output from 1342nm to 1525nm is realized by using the first-order Stokes effect of YVO4 crystal. The effects of pump power and pulse repetition rate on the average power, pulse width, waveform and output beam quality of 1525nm Raman laser are studied by using three different cavity configurations. At a LD pump power of 15.9W and a repetition rate of 30kHz, the highest average power output of 530 MW is obtained. When the pulse repetition rate is 10 kHz, the lowest threshold of LD pump is 2.6 W, and the width of 1.5 渭 m Raman laser pulse is stable at 5ns when the LD pump power is greater than 9.1 W, and the effective compression is obtained compared with the fundamental frequency optical pulse.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN248

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