LD泵浦532nm绿光及355nm紫外激光器研究

【作者】 沈兆国；

【导师】 白晋涛；

【作者基本信息】 西北大学 ， 光学， 2009， 硕士

【摘要】 LD泵浦的全固态激光技术,是利用半导体激光二极管或其阵列泵浦激光增益介质（如Nd:YAG,Nd:YVO₄,Nd:GdVO₄、Yb:YAG、Tm,Ho:YVO₄等）产生基频光,通过非线性光学频率变换晶体（如KTP、LBO、BBO、PPLN、PPKTP等）倍频、和频、差频以及准相位匹配等非线性光学技术,实现红外光-可见光-紫外光波段激光输出。本论文以LD泵浦全固态激光器为研究中心,进行理论分析和实验研究。理论方面,在回顾全固态激光器发展历程及其非线性光学频率变换技术基础上,简单分析从紫外光-可见光-红外光激光器的实现手段、应用及进展;对非线性光学理论与技术、光学谐振腔理论与技术及调Q理论与技术进行较全面探讨。实验方面,研究了基于水冷和风冷相结合的LD端面泵浦连续绿光激光器和LD侧面泵浦1064nm脉冲激光器以及电光调Q532nm/355nm脉冲激光器;实验内容的主要工作与创新点概括如下:1、设计出一套基于水冷和风冷相结合冷却系统。该系统体积小、效率高、稳定性好、噪音低,兼具有水冷和风冷优点,有利于实现高功率激光器的微型化。2、以该冷却系统对激光晶体和倍频晶体进行冷却;采用端面泵浦Nd:YVO₄腔内KTP倍频,获得稳定连续绿光激光输出;当激光晶体吸收的泵浦功率为24.3W时,获得4.2W稳定的532 nm绿光激光输出,光-光转换效率达到17.3%。3、理论探讨了脉冲激光输出功率最佳透过率,并且进行1064nm脉冲激光器实验研究,确定1064nm最佳输出透过率为60%。在不加电光调Q装置时,获得了高达102.7W脉冲激光输出;在加电光调Q装置时,获得23.6W脉冲激光输出。4、设计侧面泵浦电光调Q绿光激光器,采用平—平直腔腔外倍频,当泵浦电流为120A时,获得脉冲绿光的最高输出功率为3.62W,1064nm到532nm的转换效率为15.3%;而采用腔内倍频时候输出功率降低。5、采用Ⅱ类KTP晶体倍频与Ⅱ类LBO和频晶体临界相位匹配进行外腔和频,在电光调Q重复频率600Hz时,得到最高平均功率为375mW,脉宽为12ns,单脉冲能量为0.625mJ,峰值功率达到52.1kW的355nm紫外脉冲激光输出。最后分别从腔型设计,镜片镀膜选择、倍频晶体与和频晶体晶体选择、电光调Q晶体以及调Q方式、电源设计等方面进行分析,为实现高功率、高稳定性高光束质量的激光输出奠定基础。更多还原

【Abstract】 LD-pumped all-solid-state laser technology utilizes laser diode or array-pump laser gain medium （such as Nd:YAG, Nd:YVO₄, Nd:GdVO₄, Yb:YAG,Tm,Ho:YVO₄, etc.） to produce a fundamental frequency light. Then the fundamental frequency light by the non-linear optical frequency conversion crystals （such as KTP, LBO, BBO, PPLN, PPKTP, etc.） and nonlinear optical frequency conversion technology of doubling frequency, sum frequency, deference frequency and quasi-phase matching, obtains infrared-visible light-ultraviolet wavelengths laser output. This dissertation has made theoretical analysis and experimental study on LD-pumped all-solid-state lasers. In theory, on the basic of recalling the development of all-solid-state lasers and nonlinear optical frequency conversion technology, the ultra-violet-visible light-infrared light laser access methods , application and progress are simply explored, and the theory and technology of nonlinear optical, optical resonator and Q-switched is analyzed. In the experiment, a cooling system basing on combination of water-cooled and air-cooled of LD end-pumped continuous green laser, LD side-pumped 1064nm pulse laser and electro-optic Q-switched 532nm/355nm pulse laser are studyed. The experimental content of main work and innovation can be summarized as follows:1. The cooling system basing on a combination of water-cooled and air-cooled is designed. It is small size, high efficiency, good stability, low noise, and has the advantage of water-cooled and air-cooled in favor of high-power laser miniaturization.2. Through the system cooling laser crystal and frequency-doubling crystal, using end-pumped Nd: YVO₄ and intracavity KTP frequency-doubled, stable continuous green laser output is acquired. When the crystal absorbs the pump power of 24.3W, 4.2W of 532nm stable green laser is acquired, light-optical conversion efficiency reaching to17.3%.3. The theory of pulsed laser output power of the best transmission is analyzed. By 1064nm laser experiment, 60% of 1064nm the best transmittance laser is fixed, geting up to 102.7W laser output without electro-optic Q-switched device, 23.6W pulse laser output with it.4. Side-pumped electro-optic Q-switched green laser is designed with the plane-plane straight extra cavity doubling frequency. When the pump current is 120A, we obtain the highest green output power of 3.62W, 1064nm to 532nm of conversion efficiency of 15.3%. and found intracavity frequency doubling the output power is relatively low.5. ByⅡtype KTP frequency-doubling crystal and theⅡtype LBO deferent frequency for critical phase matching of external cavity, when electro-optic Q-switched repetition rate is 600Hz, the highest average power of 375mW, pulse width of 12ns, single pulse energy of 0.625mJ and peak power of 52.1kW of 355nm UV pulse laser is obtained.Finally, the cavity design, the lens coating selection, frequency-doubling crystal and sum-frequency crystal selection, electro-optic Q-switched, Q-switched crystal, and power supply design are analyzed, which urges the laser of high-power, high stability and the high beam quality to improve.更多还原