LD阵列半环形对称抽运的固体激光器

为解决激光晶体传导冷却与输出光束能量分布对称性之间的矛盾,针对半导体激光器(LD)抽运高功率固体激光器,提出了半环形侧面对称抽运的方式.对多LD阵列同时抽运激光晶体的吸收与增益情况进行了计算,并在实验中予以验证,采用半环形对称抽运的方式,在20Hz的工作频率下,以总抽运单脉冲276 mJ的能量获得最大63.6 mJ的圆形对称脉冲激光输出,斜效率34%.实验结果表明,采用对称抽运结构能够有效地改善输出光束的空间分布,获得较为对称的激光输出.     

Cr,Tm,Ho:YAG激光器输出的实验研究

对闪光灯泵浦Cr,Tm,Ho:YAG平平腔激光器进行了实验研究。在5Hz室温运行下,获得最大能量为217mJ的脉冲输出,其斜效率约为1.2％。利用有限元方法计算了晶体内温度的分布,分析了晶体内温度对激光阈值和斜效率的影响。模拟了光在腔内的分布,计算热晶体的焦距和晶体内光斑的大小,讨论了晶体热效应对激光输出的影响。     

中红外高能量输出复合腔抽运光参

报道了采用复合腔技术研究Nd∶YAG
激光抽运LiNbO3 晶体光参量振荡器(OPO)的实验研究结果.得到OPO输出单脉冲平均能量56.4mJ,闲频光(3097nm)脉冲平均能量
22.8mJ, 脉宽8ns,抽运光转换成参量光输出效率46%(重频1Hz～10Hz).测得角度调谐的波长范围是:信频光1479nm～1621nm,闲频光3097nm～3793nm.     

2.05μm单谐振纳秒脉冲光参量振荡器特性研究

报道了1064nm单频激光抽运的KTP晶体外腔单谐振光参量振荡器(OPO),获得了波长为2.05μm的纳秒激光脉冲输出。在平-平腔中,将2块II类相位匹配KTP晶体按走离补偿方式放置,在400 Hz重复频率下,抽运单脉冲能量达到5mJ时获得了单脉冲能量为0.9mJ的2.05μm信号光输出,其脉宽约为3.7ns,对应抽运光-信号光转换效率约为18%,光束质量因子M~2在x、y方向分别为2.08、3.03。     

中红外高能量输出复合腔抽运光参量振荡器

报道了采用复合腔技术研究Nd:YAG激光抽运LiNbO₃晶体光参量振荡器(OPO)的实验研究结果。得到OPO输出单脉冲平均能量56.4mJ,闲频光(3097nm)脉冲平均能量22.8mJ,脉宽8ns,抽运光转换成参量光输出效率46%(重频1Hz～10Hz)。测得角度调谐的波长范围是:信频光1479nm～1621nm,闲频光3097nm～3793nm。     

LD端面抽运Nd:YLF/Nd:YAG多波长脉冲激光器

报道了一台激光二极管(LD)双端面抽运Nd:YLF和Nd:YAG双晶体串接多波长输出脉冲激光器。在抽运能量40.5mJ,电光调Q重复频率500Hz的工作条件下,获得单脉冲能量约为6mJ的1064nm/1053nm双波长激光脉冲输出,光-光转换效率约为14.8%。相同抽运条件下在腔内插入I类相位匹配LBO晶体作为非线性频率转换器,获得了脉冲总能量为3.6mJ的526.5、529.0、532.0nm三波长同时输出,由抽运光到输出绿光脉冲的转换效率约为8.9%,测得光束质量因子分别为M2x=1.61,My2=1.25。     

重频Cr,Tm, Ho:YAG激光器输出特性的实验研究

根据对2.1μm波长Cr,Tm,Ho:YAG激光器输出特性的实验研究,详细分析了腔长、输出镜透过率、全反镜曲率半径和水温等因素对激光器输出的影响。在镀银腔情况下,重频5Hz时,激光阈值为47J,斜效率为1.3%,输入能量为144J时,最大输出为7.9W。重频10Hz时,激光阈值为45J,斜效率为1.1%,输入能量为121J时,最大输出为9.7W。     

环形腔高脉冲能量2μm激光器

报道了激光二极管侧面抽运Tm,Ho:LuLF晶体2μm脉冲激光器.采用环形腔结构,理论计算了腔型参数,主要确定了束腰位置和大小,便于在腔内插入调Q等器件.三方向对称侧面抽运方式,具有更好的抽运均匀性·为获得高能量的激光输小提供保障.在自由运转模式下,脉冲重复频率1 Hz,抽运能量3.25 J,获得输出激光单脉冲能量为114 mJ,光光转换效率为3.5%,系统斜率效率为8.0%.插入声光调Q,对应抽运能量2.75 J时,获得调Q激光输出35 mJ,脉冲宽度约700 ns.     

大能量窄脉宽高平均功率绿光激光器

研制了在大能量窄脉宽情况下实现高平均功率输出的绿光激光系统。利用激光二极管抽运Nd∶YAG晶体,采用RTP晶体电光调Q和主振荡功率放大的功率分摊技术,实现大能量窄脉宽高重复频率532 nm绿光激光输出。输出基频光波长1064 nm,脉冲平均能量213 mJ,工作频率100 Hz,光-光转换效率12%。采用Ⅱ类相位匹配高抗灰迹KTP晶体腔外倍频,输出绿光波长532 nm,脉冲平均能量127 mJ,工作频率100 Hz,脉冲宽度7.2 ns,光束质量20mm.mrad,532 nm插头效率2.1%。     

2.09μm纳秒钬激光抽运的磷锗锌光参量振荡器

高脉冲能量中红外激光在远程大气探测和目标识别中有着重要的应用,为了获得高脉冲能量的中红外激光输出,选用自主生长的ZnGeP2(ZGP)晶体作为中红外参量非线性晶体,晶体采用Ⅰ型相位匹配,切割角度为55°,利用自行研制的2.09μm La3Ga5SiO14(LGS)电光调QCr,Tm,Ho…YAG激光器作为ZGP光参量振荡器(OPO)的抽运源。光参量振荡器采用对抽运光具有反射的双程抽运结构以提高转换效率,采用脉宽约35ns的2.09μm调Q钬激光直接抽运ZGP-OPO,在单谐振振荡结构下获得了脉冲能量为5.9mJ的4.8μm中红外激光输出,光-光转换效率为13.1%,斜率效率为17%;在双谐振振荡结构下获得了脉冲能量为9mJ的3.7μm和4.8μm中红外激光输出,光-光转换效率为23.9%,斜率效率为26.7%。     

二极管抽运200Hz TEM00模Q开关Nd:YAG激光器

用三只QCW-600W激光二极管侧面抽运Nd:YAG激光器,在重复频率为200Hz,单脉冲注入能量为270mJ条件下,实现了29.7mJ,TEM00模调Q激光输出,M2=1.12,脉宽6.4ns,光-光转换效率11%,斜效率16.5%,输出能量不稳定度1.14%.通过KTP晶体腔外倍频,获得了单脉冲能量16.8mJ,脉宽5.6ns的绿光输出,倍频效率56.6%.     

双侧面90°抽运微通道致冷Yb:YAG板条激光器

报道了采用带有微柱镜的激光二极管阵列(LDA)双侧面90°排布抽运的Yb∶YAG板条激光器,实验中使用的激光晶体尺寸为6 mm×10 mm×1 mm,掺杂原子数分数为3%。抽运光通过自行设计的聚光系统聚焦成10 mm×1 mm的光斑进行抽运,聚光系统的效率为75%,晶体表面功率密度达到1.9 kW/cm2,晶体内抽运光交叠区的体功率密度达到38 kW/cm3,远高于阈值的1.7 kW/cm3。当激光器采用平-凹腔结构,耦合输出为6%时激光单脉冲输出能量最高为25.5 mJ,斜率效率为13%。插入声光调Q晶体后获得4.7 mJ的调Q脉冲输出,脉宽为24.8 ns。     

LD 脉冲泵浦被动调Q 窄脉冲大能量全固态激光器

利用Nd:YAG/Cr4+:YAG 键合微片激光晶体研制了被动调Q 大能量窄脉冲的全固态激光器,激光器采用脉冲激光二极管泵浦方式,设计了本振级和两级放大结构,分析了激光器系统的自激振荡和其抑制方法,在激光器本振级获得稳定脉冲激光输出的基础上,当两级放大器泵浦电流分别为83A 和85 A 时,获得了最大单脉冲输出能量为120 mJ,脉冲宽度为1.28 ns 的1 064 nm 激光输出,激光通过倍频后可得到65 mJ 的532 nm 绿光输出,其窄脉宽和高光束质量特性可为飞秒激光器啁啾放大提供良好的泵浦源。     

信号光脉冲比抽运光窄12倍的内腔式KTP光参量振荡器

在闪光灯抽运的非稳腔Nd∶YAG被动调Q激光器腔内,放置非临界相位匹配KTP晶体,构成内腔式单谐振KTP光参量振荡器(OPO)。研究了输出信号光的波长调谐性能,获得1.57~1.60μm可调谐激光脉冲。实验结果表明,1.57μm信号光的输出能量随着光参量振荡器腔长的增加而减少,脉冲宽度随着腔长的增加而有所变化;抽运能量较大时,转换效率随着抽运能量的增加趋于饱和然后逐渐下降;对此给予了合理的理论解释。当光参量振荡器的腔长为5 cm,1.06μm抽运光脉冲宽度为30 ns时,输出的1.57μm信号光的脉冲宽度为2.5 ns,能量为21.3 mJ。1.57μm信号光的脉冲宽度仅为1.06μm抽运光脉冲的1/12,总的电光能量转换效率为0.128%。     

高光束质量闲频光谐振中红外MgO:PPLN光参量振荡器

报道了采用纳秒脉冲激光器泵浦基于掺杂氧化镁周期极化铌酸锂(MgO:PPLN)晶体的高光束质量、闲频光谐振中红外光参量振荡器。通过选取曲率半径为200 mm的凹面输入镜和平面输出镜来建立平凹腔,实现了高光束质量的近-中红外激光输出。当输入的最大泵浦能量为21 mJ时,输出信号光和闲频光的最大能量分别为3.2 mJ和1.12 mJ,对应信号光和闲频光的斜效率分别为24%和9%。通过在25～200℃范围内改变MgO:PPLN晶体温度,实现信号光波长1.505～1.566μm和闲频光波长3.318～3.628μm的激光调谐输出。由于闲频光单谐振的光参量振荡器具有较大的衍射损耗和光束发散角,可以提高输出闲频光的光束质量。采用刀口法测量得到中红外激光在两个正交方向的光束质量因子分别为M_x²≈1.2和M_y²≈1.2。     

Efficient gain-switched operation of a Tm-doped silica fiber laser

We present the results from experiments relating to a gain-switched Tm-doped silica fiber laser in which a gain-switched Nd:YAG laser is used to pump the ³H₅ energy level of the Tm³⁺ dopant ion. This fiber laser configuration is the first example to our knowledge of a moderate energy gain-switched fiber laser which is pumped with a low-repetition-rate high-energy pulsed laser. For a near-optimized cavity, the gain-switched fiber laser produces a maximum pulse energy of 1.46 mJ at a maximum linear slope efficiency of 20% and a total optical-to-optical efficiency (with respect to the launched energy) of 19%. At low pump energies, the slope efficiency is approximately 40%, however, saturation of the output pulse energy is observed with the increase in the launched pump energy. We also present results from a numerical model that simulates ³H ₅-band pumping and includes all of the known pump excited-state absorption (ESA) mechanisms and, in addition, four cross-relaxation mechanisms have also been included. The calculations establish that the pump ESA mechanism contributes only a small loss factor to the overall efficiency of the laser when the Tm-doped silica fiber laser is pumped at low pump energies, however, as the pump energy is increased, losses due to pump ESA limit the amount of output energy from the fiber laser. The loss mechanism is mainly attributed to pump ESA from the ³H₄ upper laser level to the combined ³F_2,3 energy level at low launched pump energies because of the large absorption cross section for this transition and the relatively long lifetime of the ³H₄ energy level. For harder pumping conditions, the majority of the excited state population resides in the ¹G₄ level, inhibiting in some laser configurations gain-switching of the fiber laser until cessation of the pump pulse itself     

3.77-5.05-/spl mu/m tunable solid-state lasers based on Fe/sup 2+/-doped ZnSe crystals operating at low and room temperatures

Spectroscopic properties and lasing of Fe:ZnSe and co-doped Fe:Cr:ZnSe crystals in the mid-infrared spectral range were studied at room and low temperatures. Using a free-running Er:YAG laser as a pump source, the output energy of the thermoelectrically cooled Fe:ZnSe laser was 142 mJ with 30% slope efficiency at T=220 K. Passive Q-switched oscillation of Er:YAG laser with Fe:ZnSe crystal was demonstrated and used as a pump source for a Fe:ZnSe laser system. Room-temperature (RT) gain-switched lasing of Fe:ZnSe was achieved in microchip and selective cavity configurations using Q-switched Er:YAG and Raman-shifted Nd:YAG lasers as pump sources. The microchip laser threshold of 100 mJ/cm/sup 2/ was demonstrated using a Fe:ZnSe crystal without any reflection coatings. A slope efficiency of 13%, oscillation threshold of 1.3 mJ, and tunable oscillation of Fe:ZnSe laser systems over 3.95-5.05 /spl mu/m spectral range were realized at RT.