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题名	高重频高功率脉冲蓝光全固态激光器技术研究
作者	黄晶
学位类别	博士
答辩日期	2015
授予单位	中国科学院上海光学精密机械研究所
导师	陈卫标
关键词	全固态激光器 Nd:YAG准三能级 Nd:YAP1.3μm激光 调Q技术 倍频技术 高重复频率
其他题名	Study of all-solid-state pulsed blue laser with high repetition rate and high power
中文摘要	在激光研究领域内，可见光波段的全固态绿光激光器具备较成熟的技术，已经实现商业化。全固态蓝光激光器在激光功率、亮度、重频、光束质量等指标上与绿光激光器还存在很大差距，发展相对缓慢。但是蓝光激光器在高密度光存储、激光显示、生物工程、水下通信和海洋环境探测等领域都有广泛的应用，一直得到高度关注。 本论文首先对蓝光激光的应用、产生途径及发展状况做了系统的介绍和归纳。研究了端面泵浦的准三能级激光器的热效应，分析了准三能级激光系统的产热机制以及几种掺Nd3+激光介质的准三能级特性，介绍了几种激光晶体热效应的缓解和补偿方法。采用有限元法，模拟4种常用的电光晶体KD*P、LN、BBO、RTP的温度和应力分布，并分析了由温度和应力所致的退偏损耗，介绍了几种电光晶体热效应的缓解和补偿方法。 研究LD端面泵浦Nd:YAG准三能级连续激光器的再吸收效应，理论和实验分析了Nd:YAG 946 nm激光器输出功率、注入泵浦功率以及温度对再吸收效应的影响。选用凸凹非稳腔对准三能级的热效应进行热补偿，对比普通Nd:YAG晶体、不同掺杂复合Nd:YAG晶体的热效应和激光输出性能。在泵浦功率22.3 W时，采用掺杂0.5 at.%的复合晶体作为增益介质时，946 nm激光的空腔输出功率达到4.34 W。光谱仪测量输出激光中心波长为945.99 nm，谱宽1.37 nm，并对1064 nm实现了有效抑制。 为获得1 kHz电光调Q的Nd:YAG 946 nm激光输出，采用双RTP晶体作为电光晶体。实验中观察到RTP晶体的热致双折射现象，提出λ/4波片补偿的方式用于电光晶体的热效应补偿中，实验验证了补偿方法的可行性，通过优化谐振腔腔长和输出镜透过率，在泵浦功率11.1 W时，获得410 mW脉冲946 nm激光输出，对应光-光转换效率3.7%，斜效率5.5%，此时重复频率为1 kHz，脉冲宽度为15.4 ns。水平方向的M2值为1.6，竖直方向的M2值为1.3。20分钟运转时间内，激光器的功率不稳定性为2.6%。 对脉冲946nm进行腔外倍频，获得473 nm脉冲蓝光输出。选用I类相位匹配的LBO晶体(θ=90°,φ=19.3°)，为提高腔外倍频效率，采用双程倍频和双LBO晶体串接的方式。注入基频光946 nm的功率为410 mW时，473 nm蓝光激光输出的最大平均功率为80.2 mW，相应的倍频转换效率为19.6%。重复频率为1 kHz，脉冲宽度为10.5 ns。水平方向的M2值为1.6，竖直方向的M2值为2.1。中心波长473.79 nm，谱宽3 nm。20分钟内，腔外倍频473 nm蓝光功率不稳定性约为5.6%。 进一步探索了三倍频Nd:YAP 1.3 μm激光器获得447 nm脉冲蓝光激光技术。采用LD端面泵浦的方式，泵浦功率21.2 W时，获得最大平均功率为2.34 W的1341.4 nm激光输出，对应的光-光转换效率为11%，斜效率为15.1%。重频5 kHz的声光调Q实验中，泵浦功率20.5 W时，获得0.83 W脉冲1341.4 nm激光输出，脉冲宽度33 ns，峰值功率为5.03 kW。采用II类相位匹配的KTP晶体(θ=58.9°,φ=0°)作为倍频晶体，I类相位匹配的LBO晶体(θ=90°,φ=19.9°)作为和频晶体进行三倍频实验，腔外和频获得670.7 nm红光激光的最大功率为100 mW，对应的基频光到红光的转换效率为12%，脉冲宽度19.4 ns；获得447 nm蓝光激光的最大功率为35.5 mW，对应的基频光到蓝光的转换效率为4.26%，脉冲宽度18.5 ns。腔内和频获得447 nm蓝光激光的最大功率为60.4 mW，对应的基频光到和频光的转换效率为0.29%，脉冲宽度为16.1 ns。水平方向的M2值为2.5，竖直方向的M2值为2.2。输出激光的中心波长为447.74 nm，谱宽2.64nm。
英文摘要	All-solid-state green laser has been the more mature technology and commercialization. However, all-solid-state blue laser is developed relatively slowly, therefore the power, brightness, beam quality has large gap comparing to green laser. While, blue laser has extensive application prospects in high-density optical storage, laser display, biological engineering, ocean color and marine resources exploration and other fields. First of all, a comprehensive overview and analysis on the development of all-solid-state blue lasers have been summarized. The analysis of thermogenesis mechanism and laser medium has been reviewed. Mitigation and compensation methods of thermal effect of laser crystals are present. With the method of finite element analysis, the temperature and stress distribution of KD*P、LN、BBO、RTP electro-optical crystals are simulated. Depolarization loss caused by temperature and stress is calculated. In addition, some kinds of mitigation and compensation methods of thermal effect of electro-optical crystals are proposed. Re-absorption effect of LD end pumped Nd:YAG quasi-three-level CW laser is investigated. Influence of the output power of Nd:YAG 946 nm laser, incident pump power and temperature on re-absorption effect are analyzed theoretically and experimentally. By using of a convex concave resonator to compensate the thermal effect of quasi-three-level laser, we compare the thermally effect and laser output performance of un-composite Nd:YAG crystal and composite Nd:YAG crystals with different doping. When the pump power is 22.3 W, the output power of 946 nm is 4.34 W by using of 0.5 at.% doped composite Nd:YAG crystal as gain medium. The center wavelength is 945.99 nm and the spectral width is 1.37 nm. No any 1064 nm laser is lasing. To realize 1 kHz electro-optically Q-switched Nd:YAG 946 nm laser, a double RTP crystal is used as the Q-switcher. A depolarization phenomenon in an electro-optical crystal in a quasi-three-level 946 nm Nd:YAG laser is observed. A compensation of the thermal effects in electro-optical crystals is achieved by employing a quarter-wave plate, with one optical axis parallel to the laser polarization. This technique allows for the production of an electro-optically Q-switched 946 nm Nd:YAG laser at 1 kHz. By optimizing the resonator cavity length and the output mirror transmittance, a maximum output power of 410 mW at 1 kHz repetition frequency and 15.4 ns pulse duration are achieved under the incident pump power of 11.1 W. The beam quality factors for pulsed 946 nm laser at the maximum output power are M_x^2=1.6 and M_y^2=1.3, and the power instability is 2.6% in 20 minutes. A pulsed blue laser is obtained by means of an extracavity frequency-doubling of EO Q-switched 946nm laser. The I kind of phase matching (90°, 19.3°)nonlinear optic crystal LBO is joined in to this system and two-pass frequency doubling and two LBO crystals are used to improve the frequency doubling efficiency. When the power of 946 nm is 410 mW, the highest output power of 473 nm blue laser is 80.2 mW at 1kHz, with the pulse width of 10.5 ns and the conversion efficiency of 19.6%. The beam quality factors for pulsed 946 nm laser at the maximum output power are M_x^2=1.6 and M_y^2=2.1. The center wavelength is 473.79 nm and the spectral width is 3 nm, and the power instability is 5.6% in 20 minutes. In order to further explore the ways to generate blue laser, 447 nm generated by using of triple frequency of Nd:YAP 1.3 μm laser is investigated. When the pump power is 21.2 W, the output power of 1341.4 nm is 2.34 W, with the corresponding optical-optical conversion efficiency of 11% and a slope efficiency of 15.1%. The highest peak power of 5.03 kW acoustic-optically Q-switched 1341.4 nm laser is obtained at 5 kHz, with the pulsed width of 33 ns, at the pump power of 20.5 W. We choose II kind of phase matching (58.9°, 0°)nonlinear optic crystal KTP as a frequency-doubling crystal and I kind of phase matching (90°, 19.9°)nonlinear optic crystal LBO as a frequency tripler. In the case of extracavity harmonic generation, the highest output power of 670.7 nm red laser and 447 nm blue laser is 100 mW and 35.5 mW, respectively, with the pulse width of 19.4 ns and 18.5 ns and the conversion efficiency of 12% and 4.26%, respectively. In the case of intracavity frequency-tripling, the highest output power of 447 nm blue laser is 60.4 mW, with the pulse width of 16.1 ns and the conversion efficiency of 0.29%. The beam quality factors for pulsed 946nm laser at the maximum output power are M_x^2=2.5 and M_y^2=2.2. The center wavelength is 447.74 nm and the spectral width is 2.64nm.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/15908]
专题	上海光学精密机械研究所_学位论文
推荐引用方式 GB/T 7714	黄晶. 高重频高功率脉冲蓝光全固态激光器技术研究[D]. 中国科学院上海光学精密机械研究所. 2015.

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