基于LD泵浦铯蒸汽激光器的倍频蓝紫激光技术研究

发布时间：2018-03-09 10:56

本文选题：半导体泵浦气体激光器　切入点：半导体泵浦铯蒸汽激光器　出处：《中国科学院研究生院(长春光学精密机械与物理研究所)》2016年博士论文　论文类型：学位论文

【摘要】：蓝紫激光光源在激光光谱学、原子物理、激光医疗、环境监测、激光显示及激光水下通信与探测等一系列基础研究、高科技产品开发和国防工程中有着非常重要的应用。通过倍频LD泵浦掺Nd3+准三能级固体激光器(diode-pumped solid-state laser,DPSSL,0.9μm)是目前产生蓝紫激光常用的技术方案。与之相比,近年来受到广泛关注和研究的LD泵浦碱金属蒸汽激光器(diode-pumped alkali vapor laser,DPAL)具有量子效率高、受激吸收/辐射截面大、折射率扰动小、输出线宽窄等优点,具有研制效率更高的蓝紫激光光源的潜力。鉴于此,本文从理论和实验方面对基于LD泵浦的铯蒸汽激光(Cs-DPAL)倍频蓝紫激光技术开展了以下研究：1、简要地介绍了Cs-DPAL的关键技术,包括：Cs蒸汽原子吸收线宽和泵浦源线宽之间的匹配技术、Cs原子精细结构之间的碰撞弛豫以及半导体激光的泵浦技术。采用速率方程理论,对Cs蒸汽池的温度、泵浦光的线宽、缓冲气体的压强和输出镜反射率,对Cs-DPAL输出功率的影响进行了计算和分析。搭建了两台Cs-DPAL,在连续工作方式下当泵浦功率为10W时,可分别输出功率0.55W和1.44W；在脉冲工作方式下当泵浦功率为16W时,可分别输出功率0.692W和2.6W,并对两台Cs-DPAL的光束质量进行了测量,分别为Mx2=1.02,My2=1.13和Mx2=2.13,My2=2.66。2、采用远场条件下的高斯光束倍频理论,对Cs-DPAL可实现相位匹配的常用的倍频晶体,LBO、BBO、BIBO以及ppKTP晶体,通过Ⅰ类相位匹配的方式腔外倍频Cs-DPAL时,聚焦参数和倍频晶体温度对倍频效率的影响进行了计算。此外对上述除ppKTP之外的其它三种晶体,通过Ⅱ类相位匹配方式倍频Cs-DPAL时,Cs激光在倍频晶体内的光束半径和束腰位置,对倍频效率的影响进行了分析。采用搭建的两台Cs-DPAL进行腔外倍频实验。对于光束质量因子分别为Mx2=1.02,My2=1.13和Mx2=2.13,My2=2.66的Cs-DPAL,在脉冲工作方式下,分别可实现蓝紫激光输出功率9.5μW和11.2μW,并就光束质量对倍频效率的影响进行了讨论和分析。3、基于速率方程理论,建立了描述腔内倍频Cs-DPAL的两种算法,对倍频光功率、倍频晶体最优长度和腔内倍频准二能级极限的Cs-DPAL进行了计算和分析。采用LBO晶体进行了腔内倍频Cs-DPAL实验,对于连续和脉冲工作方式,当LD泵浦光功率为16W时,倍频光功率分别为0.22mW和0.36mW,通过高斯拟合可知,倍频光功率随晶体温度变化曲线的半高全宽约4.1℃。4、采用分步傅里叶法(Split-Step method),对LBO、BBO和BIBO晶体,通过Ⅰ类相位匹配方式倍频Cs-DPAL时,Cs激光和倍频光在晶体内的光强分布、倍频效率、倍频光的光束质量因子进行了仿真和计算。也对LBO晶体通过Ⅱ类相位匹配方式倍频Cs-DPAL进行了类似的计算。对不同功率和不同束腰半径的Cs激光,入射LBO晶体时产生的温度分布进行了计算。较为详细地讨论了晶体内的温度分布对倍频过程,包括对倍频效率、倍频光光束质量以及倍频光光强分布的影响。
[Abstract]:Blue violet laser light in laser spectroscopy, atomic physics, laser medical, environmental monitoring, laser display and laser underwater communication and detection of a series of basic research, it has a very important application of hi-tech product development and national defense project. Through the frequency doubling of LD pumped Nd3+ quasi three level solid-state laser (diode-pumped solid-state laser DPSSL. 0.9 m) is currently the technical plan for generating blue violet laser used. In contrast, in recent years by LD pumped alkali vapor laser wide attention and Research (diode-pumped alkali vapor laser, DPAL) with high quantum efficiency, stimulated absorption / emission cross section, refractive index perturbation is small, narrow linewidth output etc. with the development of high efficiency, blue violet laser light source potential. In view of this, this paper from the aspects of theory and experiment of laser pumped cesium vapor LD (Cs-DPAL) based on frequency doubling blue laser technology to carry out The following research: 1, briefly introduces the key technologies of Cs-DPAL, including: Cs steam matching technology between atomic absorption linewidth and pump linewidth, between the fine structure of Cs atom collision relaxation and semiconductor laser pumping technique. By using the rate equation theory, the temperature of Cs steam tank, pump light linewidth, buffer the gas pressure and the output mirror reflectivity, influence on output power of Cs-DPAL was calculated and analyzed. Set up two Cs-DPAL in continuous way when the pump power is 10W, the output power of 0.55W and 1.44W respectively; under the pulse mode when the pump power is 16W, respectively, and the output power of 0.692W 2.6W, and two sets of Cs-DPAL beam quality are measured, respectively Mx2=1.02, My2=1.13 and Mx2=2.13, My2=2.66.2, the frequency doubling theory of Gauss beam in the far-field condition, can realize the phase matching of Cs-DPAL Crystal, with the commonly used LBO, BBO, BIBO and ppKTP type phase matching crystal, by way of external cavity frequency doubling Cs-DPAL, influence of focusing parameters and the frequency doubling crystal temperature on the frequency doubling efficiency was calculated. In addition to the above except ppKTP and other three kinds of crystal, frequency doubling Cs-DPAL matching through class II phase, Cs laser in the intracavity beam radius and beam waist position, influence on the frequency doubling efficiency was analyzed. The structures of the two sets of Cs-DPAL cavity doubledexperiment. The beam quality factor are respectively Mx2=1.02, My2=1.13 and Mx2=2.13, My2=2.66 Cs-DPAL, under the pulse mode, can realize the blue violet laser the output power of 9.5 W and 11.2 W respectively, and discussed the.3 effect of beam quality on the frequency doubling efficiency, based on the theory of rate equation was established to describe the two algorithms of the intracavity frequency doubled Cs-DPAL times. Frequency doubling crystal optical power, optimal length and intracavity frequency doubling quasi two level limit of Cs-DPAL were calculated and analyzed. The experiment used LBO intracavity frequency doubling of Cs-DPAL crystal for continuous and pulse mode, when the LD pump power is 16W, frequency doubling light power were 0.22mW and 0.36mW, by Gauss fitting, half the second harmonic light power with the crystal temperature curve of the full width of about 4.1 DEG.4, using the split step Fourier method (Split-Step method), LBO, BBO and BIBO crystal, by way of Cs-DPAL type phase matching SHG, Cs laser and the frequency doubling light intensity distribution in the crystal, the frequency doubling efficiency, frequency doubling light beam quality factor the simulation and calculation. Also carried out similar calculations on LBO crystal by type II phase matching SHG. Cs-DPAL Cs laser with different power and different beam radius, produce incident LBO crystal temperature The distribution is calculated. The effect of temperature distribution on the frequency doubling process, including the frequency doubling efficiency, the frequency doubling beam quality and the intensity distribution of frequency doubling light, is discussed in detail.

【学位授予单位】：中国科学院研究生院(长春光学精密机械与物理研究所)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN248

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