【作者】 盛芳；

【导师】 陈军；

【作者基本信息】 浙江大学 ， 光学工程， 2004， 博士

【摘要】 LD抽运的微片激光器以其体积小、性能稳定、寿命长、效率高的优势在激光雷达、生物医学、微机械、测距、遥感、环境监测、空间光通信等许多领域具有广泛的应用前景，成为激光器件领域中一个倍受关注的热点。为了获得窄脉宽、高重复频率和稳定、可控的脉冲激光来作为种子光源或MOPA系统的振荡级，本文研究了LD抽运微片激光器两种重要的短脉冲产生方法：被动调Q和增益开关，展开了理论分析、模拟计算、实验验证和参量优化的工作。围绕提高微片激光器脉冲输出特性这个目标运用了新的方法、提出了新的见解，取得了如下成果： 在掺Cr⁴⁺被动调Q激光器的速率方程求解过程中，提出将谐振腔参量和可饱和吸收体参量归结为两个综合参量的新方法，通过四能级速率方程的求解得到了调Q脉冲能量、峰值功率、脉宽与这两个综合参量的关系。 在双掺Cr⁴⁺，Nd³⁺：YAG微片激光器中，利用直流预抽运技术获得高稳定、重复频率为1Hz～4kHz的Q脉冲激光输出。研究了两段式Cr⁴⁺：YAG-Nd³⁺：YAG组合单晶自调Q激光器，获得脉宽为10ns、重复频率为10kHz的高重频短脉冲调Q激光输出。运用前述新方法进行理论分析，获得了与实验较吻合的结果。 建立了四能级激光器增益开关效应的理论模型，首次计算得到输出激光脉冲特性参量随LD直流抽运电流、叠加脉冲抽运电流和抽运脉宽等抽运参量的变化关系。以提高输出峰值功率、压缩输出脉宽为目标，给出了LD抽运的最佳条件。并在抽运参量优化理论的指导下，对输出脉冲特性进行了优化，实验上将脉冲宽度进一步压缩为16ns。 研制成一体化、小型Nd³⁺：YVO₄增益开关激光器，利用自制的调制信号发生器，获得了重复频率在1Hz～25kHz范围内精确可控而稳定的激光脉冲输出，可作为重复频率稳定可控的激光脉冲种子源。 探索性实验研究了增益开关与被动调Q共同作用的双掺杂Cr⁴⁺，Nd³⁺：YAG微片激光器，获得了重复频率在1Hz～25kHz、脉宽6ns的稳定脉冲激光输出。更多还原

【Abstract】 LD-pumped microchip lasers combine many advantages such as compactness, reliability, high beam quality, high efficiency and long lifetime. They are of great interest in the field of laser radar, biomedicine, micro-mechanism, range finder, remote sensing, pollution detection and space optical communication, etc. They have been a hot point in laser technology and devices.To get stable and controllable laser pulses with short duration and high repetition rate for a seed source in MOPA system, the dissertation focuses on two important technology to generate short pulses: passive Q-switching and gain-switching. The theory analyses, simulation calculations, experiment researches and parameters optimization have been made. Some new methods and opinions have been presented for enhancing the output characteristics of LD-pumped microchip lasers.During the solution process of the rate equations of Cr~4+ doped passive Q-switched lasers, many parameters of resonance cavity and saturable absorber are integrated into two synthesis parameters. The relationship of and the energy, peak power and duration of Q-switched laser pulses with the synthesis parameters are calculated.Using pre-pumping technique, the highly stable Q-switched laser pulses with repetition rate from 1Hz to 4kHz was acquired in a Cr~4+,Nd~3+:YAG microchip laser. The two-section Cr~4+:YAG-Nd~3+:YAG laser was studied and the self-Q-switched laser pulses with duration of 10ns and 10kHz repetition-rate were acquired. The experimental results accord well with the theory calculations.In the dissertation, the gain-switching model of four-level lasers is established. For the first time, the variation of the laser output characteristics with LD pump direct current, pump pulse current and pump pulse width was calculated by numerically solving the model. Furthermore the optimal LD pump parameters were acquired aiming to get maximum peak power and minimum pulse duration. By the optimization of pump parameters, the duration of output laser pulse was compressed to 16ns.A monolithic small Nd~3+:YVO4 gain-switched laser was developed. Stable laser pulses with repetition rate varied in a large range of lHz-25kHz were acquired with homemade modulation signal generator.A Cr~4+,Nd~3+:YAG microchip laser was primarily explored in experiments under dual mechanism of gain-switching and Q-switching taking effect together. Stable laser pulses with duration of 6ns and repetition rate of lHz-25kHz were obtained.更多还原