激光二极管侧面泵浦的高效率Nd：YAG激光器

用准连续激光二极管列阵侧面泵浦Ｎｄ：ＹＡＧ固体激光器，获得３９．５ｍＪ的静态输出，器件重复频率为５０Ｈｚ，效率最高达３９．５％，对该器件进行了细致的实验研究，验证了理论计算的正确性，并对实验结果进行了分析。     

An Efficient LD Pumped Nd:glass Laser

ＡｎＥｆｆｉｃｉｅｎｔＬＤＰｕｍｐｅｄＮｄ：ｇｌａｓｓＬａｓｅｒＬＵＪｉａｎｇ；ＷＡＮＧＹａｎｇｉｕｎ；ＨＵＡＮＧＺｈａｏｍｉｎｇ；ＪＩＮＺｈｅｎｈｏｎｇ（ＷａｖｅＳｃｉｅｎｃｅＬａｂ．，ＳｈａｎｇｈａｉＵｎｉｖｅｒｓｉｔｙ，Ｓｈａｎｇｈａｉ２０１８...     

890 mW Diode Pumped Nd:YVO4 Intracavity-doubled Red Light Laser

A diode-pumped Nd3+:YVO4 emitting at 1342 nm and 671 nm was developed. Low concentration neodymium doped Nd:YVO4 shows excellent stability at 1342 nm. With a type-Ⅱ noncritical phase-matched LBO crystal as the intracavity frequency doubler, 890 mW of 671 nm light was obtained at 11.2 W incident pumping power, the optical-optical conversion efficiency is 7.9%.     

890 mW Diode Pumped Nd:YVO4 Intracavity-doubled Red Light Laser

A diode-pumped Nd3+:YVO4 emitting at 1342 nm and 671 nm was developed. Low concentration neodymium doped Nd:YVO4 shows excellent stability at 1342 nm. With a type-Ⅱ noncritical phase-matched LBO crystal as the intracavity frequency doubler, 890 mW of 671 nm light was obtained at 11.2 W incident pumping power, the optical-optical conversion efficiency is 7.9%.     

LD抽运Nd:GdVO4的激光性能研究

利用LD端泵NdGdVO4晶体,实现了激光器的1 063 nm连续和调Q激光输出.在连续激光输出实验中,在泵浦功率为20.2 W时,得到最高的光-光转换效率为55.0%,斜效率为59.1%,此时输出功率为11.5 W;在泵浦功率为33.7 W时,得到16.7 W的最大激光输出.在调Q实验中,当重复频率为10 kHz时,获得脉宽6.5 ns,能量340 μJ,峰值功率52.3 kW.当重复频率为30 kHz时,获得脉宽14.5 ns,平均输出功率5.18 W,峰值功率11.9 kW.     

激光二极管泵浦Nd：LMA激光器的连续波输出研究

报道有一个３Ｗ激光二极管端面泵浦Ｎｄ：ＬＭＡ激光器，实验采用三镜折迭像散补偿腔。在１０５４ｎｍ波长，激光器连续输出功率达６２０ｍＷ，斜率效率为５０％，光－光转换效率２０％，在１０８３ｎｍ波长处，激光器连续输出功率为６４ｍＷ，斜率效率为６％，光转换效率２．１％。     

一种能补偿热效应的高功率端面泵浦Nd:YVO4激光谐振腔的设计

针对激光二极管端面泵浦的Nd:YVO₄全固态激光器,提出了一种利用双晶体,对Nd:YVO₄的热效应进行补偿的方案,同时该方案又能提高最大输出功率,避免由于插入附加光学元件所导致的损耗,满足调Q以及提高腔内倍频效率的要求.     

Laser-diode-pumped Passively Q-switched Nd:Sr5(VO4)3F Laser with Cr4+: YAG Saturable Absorber

Cr4+:YAG is a new saturable absorber for passive Q-switching. As a passive Q-switcher, it has several excellent properties, such as low saturation fluence, high damage threshold, good thermal conductivity, no degradation and so on. By using a laser-diode as pumping source and Cr4+ :YAG as passive Q switcher, the passive Q-switching run in Nd: Sr5(VO4)3F laser at 1. 065 μm is realized. The average output power, the single pulse energy, the pulse width and the repetition rate for different small-signal transmission of Cr4+:YAG and different pumping power were measured. Meanwhile, the coupling rate equations for Cr4+:YAG as passive Q-switcher were given and the experimental results agreed with the numerical solution of equations.     

激光二极管端面抽运Nd:YVO4板条激光器及其热效应

激光器中激光介质采用板条状几何结构可以极大地降低它的热效应,但仍然需要进一步分析其影响,进而优化激光器效率.利用有限元分析方法分析了部分端面抽运的混合腔板条激光器中激光介质的热效应,计算的热透镜焦距与实测结果基本相符.分析了热效应对模式匹配的影响,分析结果对于优化激光器效率、改进谐振腔设计具有一定的参考价值.并在分析的基础上进行了混合腔实验,抽运功率为110 W时,获得连续输出激光功率41.5 W,光光转换效率约38%,斜效率达58.8%,M2因子为非稳腔方向M2x＝1.59,稳定腔方向M2y＝1.55.     

Stabilization of a Mode-Locked Nd: Glass Laser by Intracavity Second-Harmonic Generation

A method is described for generating stabilized, intensity-limited pulsetrains from a mode-locked Nd:glass laser with internal second-harmonic generation.     

钕玻璃的热致断裂及泵浦极限

以激光介质的第一主应力为评判标准,依据Griffith微裂纹理论作为断裂临界应力,基于已报道的断裂实验数据和3维、瞬态的有限元计算,建立了预测一定泵浦参数下钕玻璃断裂可能性的Weibull统计模型,同时分析了影响介质泵浦极限的其它因素。结果表明：材料的抛光工艺决定了介质的断裂应力;对于短脉冲大能量方式工作的钕玻璃介质,基于美国20世纪90年代的抛光水平,1 Hz以下低重频时应优先考虑18 kWcm-2的泵浦饱和极限,10 Hz以上高重频时应优先考虑介质的断裂极限。     

Laser-diode-pumped Passively Q-switched Nd:Sr5(VO4)3F Laser with Cr4+:YAG Saturable Absorber

Cr4+:YAG is a new saturable absorber for passive Q-switching. As a passive Q-switcher, it has several excellent properties, such as low saturation fluence, high damage threshold, good thermal conductivity, no degradation and so on. By using a laser-diode as pumping source and Cr4+ :YAG as passive Q switcher, the passive Q-switching run in Nd: Sr5(VO4)3F laser at 1. 065 μm is realized. The average output power, the single pulse energy, the pulse width and the repetition rate for different small-signal transmission of Cr4+:YAG and different pumping power were measured. Meanwhile, the coupling rate equations for Cr4+:YAG as passive Q-switcher were given and the experimental results agreed with the numerical solution of equations.     

钕玻璃的热致断裂及泵浦极限

以激光介质的第一主应力为评判标准,依据Griffith微裂纹理论作为断裂临界应力,基于已报道的断裂实验数据和3维、瞬态的有限元计算,建立了预测一定泵浦参数下钕玻璃断裂可能性的Weibull统计模型,同时分析了影响介质泵浦极限的其它因素。结果表明:材料的抛光工艺决定了介质的断裂应力;对于短脉冲大能量方式工作的钕玻璃介质,基于美国2 0世纪9 0年代的抛光水平,1 Hz以下低重频时应优先考虑18 kW.cm-2的泵浦饱和极限,10 Hz以上高重频时应优先考虑介质的断裂极限。     

不同泵浦光下Nd:GdVO4晶体输出特性

为研究808 nm和879 nm两种泵浦光对Nd:GdVO4晶体激光输出特性的影响,并比较两种不同波长泵浦所得连续输出光的效率高低,分析了Nd:GdVO4晶体的能级结构和两种泵浦光作用下的激光输出特性,发现在879 nm也有较强的吸收峰.用808 nm和879 nm两种不同波长泵浦Nd:GdVO4晶体的过程是不同的,808 nm泵浦是一种间接方式能量转移的过程,在此过程中有明显的热负载产生.而879 nm泵浦是将粒子直接激励到激光辐射上能级,降低无辐射弛豫过程产生的热量.从理论上可知,879 nm的泵浦量子效率要高于808 nm的泵浦量子效率,对减少晶体的热产生有很强的优势.实验中采用激光二极管端面泵浦Nd:GdVO4晶体直腔方案,研究了两种不同泵浦光泵浦Nd:GdVO4晶体以获得1 063 nm的连续光,得到了两种光抽运时的斜效率,发现在同样实验条件下,879 nm泵浦的输出光斜效率在小功率泵浦时略高于808 nm|而在大功率泵浦的情况下明显高于808 nm,最高达到38%.同时,在808 nm抽运时,实验上获得了1 341 nm波长的激光,为光通讯的应用提供了一种光源.     

端面泵浦双Nd: YVO4激光器中热效应对腔稳定性的影响

利用多个激光晶体串接方式可以提高固体激光器的输出功率. 发展双Nd: YVO₄晶体激光器, 将晶体的端面镀膜作为谐振腔的端面镜, 构成了平行平面谐振腔. 对平行平面谐振腔的等效腔进行了理论分析, 结果表明激光晶体吸收泵浦光产生的热透镜效应对保持腔的稳定性起到了重要的作用. 在国内首次进行了双端泵浦双Nd: YVO₄激光器的实验研究, 在抽运功率为 20.74 W时获得了11 W的1064 nm TEM00模激光输出, 其光-光转化效率约为53%. 并且对于不同掺杂浓度下的实验结果进行了讨论.     

半导体激光泵浦Nd：YVO4激光器的1.34μm输出特性

报道了半导体激光泵浦Ｎｄ：ＹＶＯ４激光器在１．３４μｍ的输出特性，当入射的泵浦光功率为５１５ｍＷ时，最大１．３４μｍ激光输出功率达１５７ｍＷ，光－光转换效率为３０．５％，研究了激光器的纵模特性及弛豫噪声与泵浦功率的关系，发现不同的纵模具有各自不同的弛豫振荡频率。     

Experimental Investigation of Thermal Lensing in End-pumped Nd:YVO4 Crystal Using a New Simple Approach

The stability of linear planar resonators involved in solid-state lasers is entirely decided by the thermal lens of the laser crystal. There exists a critical point between stable state and unstable state at which the thermally focusing point falls on the surface of one end mirror. Based on this fact, a new method for measuring the thermal focal length has been presented, and applied to three different Nd3+-doped (2%, 0.8%, and 0.5% ) Nd:YVO4 crystals at various absorbed pump power levels up to 10 W, the results show a good agreement with those of theoretical calculation. It also indicates that the thermal lensing is strongly dependent on the Nd3+-doped concentration, and is affected by crystal surface temperature, especially in the situation of weak thermal lensing.     

激光二极管泵浦Nd∶Sr_5(VO_4)_3F激光器的输出特性研究

分析了Ｎｄ∶ＳＶＡＰ晶体在Ｘ（ａ）－轴和Ｙ－轴不同切割情况下的偏振吸收和荧光谱，并对沿不同方向切割样品的激光特性进行了研究。发现沿Ｘ轴方向切割样品的荧光谱的偏振度为４．４１，而沿Ｙ轴方向切割样品的偏振度为２．１８。并且，沿Ｘ轴方向切割样品的π偏振荧光谱的强度是沿Ｙ轴切割样品的１．７倍。还报道了对激光器输出中心波长与泵浦功率大小的关系以及输出功率的大小与激光晶体温度关系的研究结果     

激光二极管抽运的被动调QNd3+:YAG微晶片激光器及其稳定性

从理论和实验两个方面研究了连续激光二极管抽运的Cr~(4+):YAG被动调QNd~(3+):YAG微晶片激光器。考虑Cr~(4+):YAG饱和吸收体激发态吸收,推导了连续抽运的被动调Q微晶片激光器的速率方程,分析了微晶片参量对调Q脉冲半峰全宽和峰值功率的影响;提出了实现稳定脉冲输出的微晶片激光器设计原则。在饱和吸收体初始透过率较低(T_0≈40％)的情况下,获得了脉冲峰值功率不稳定性小于±0.7％、脉冲宽度不稳定性小于±1.0％、峰值功率高达千瓦量级的高重复频率激光输出。     

Dependence of the refractive power of Nd:YAG rods on the intracavity intensity

The refractive power of two flashlamp-pumped Nd:YAG rods was measured as being dependent on the output coupling of the resonator. With laser oscillation, the refractive power or thermal heat is decreased by up to 15% and a minimum occurs at a specific output coupling. The experimental results could be explained by a theoretical model assuming a non-radiative transition from the upper laser level to the ground state. The lifetime of this non-radiative transition decreases with increasing pumping power per pulse and, for pumping power higher than 100 kW, saturation at a value of 0.63 times the fluorescence lifetime occurs. The results indicate that the non-radiative process is caused by energy migration to flashlamp-induced transient quenching centres.