氩离子激光泵浦的Nd:YAG单晶光纤激光器

本文报道了以氩离子激光作泵浦源的Nd:YAG单晶光纤激光器的研究结果。获得了波长为1.064μm基模的连续激光输出。其斜率效率高于20％;最高激光输出达35mW。实验结果与理论计算基本吻合     

光学传感器对水下Nd:YAG深熔激光焊接过程检测的研究

水下激光焊接是一种用于核电站堆芯构件和压力容器的关键维修技术,本文对水下激光焊接产生的红外光辐射信号与焊接质量的关系进行了研究。实验结果表明,当工件表面的水深超过3mm时,一种蓝色的非金属等离子体将形成并对激光产生强烈的衰减,焊缝的熔深不到正常焊接条件下的1/20。利用气体喷嘴在工件表面形成局部于燥空间,研究了不同喷嘴直径、气体流量条件下光信号和焊缝质量的关系,得到了光信号的波动幅值与局部干燥空间的合适保护条件的关系。     

High-power long-pulse second harmonic generation and optical damage with free-running Nd:YAG laser

Frequency doubling with a free-running long-pulse Nd:YAG laser and LBO or KTP nonlinear crystals yields conversion efficiency of up to 17.5% and 162 W peak power in the second harmonic. This efficiency is obtained for a TEM/sub 00/ beam with rectangular temporal pulse shape of 50 to 400 /spl mu/s. To our knowledge, this is the highest second-harmonic generation (SHG) efficiency reported for the long-pulse free-running configuration. The efficiency is limited by optical damage with much lower threshold than in the Q-switch domain. The damage is preceded by a saturation effect of the SHG efficiency. Both wavelengths (fundamental and second-harmonic) are necessary for the creation of the catastrophic damage. We present first evidence for a mechanism that involves creation of transient absorption centers by the second-harmonic radiation due to multiphoton absorption. Absorption of the fundamental wave at these centers leads to local heating and ultimately catastrophic damage.     

Two-frequency injection-seeded Nd:YAG laser

Dual longitudinal mode (DLM) operation of a Nd:YAG laser is achieved by simultaneously injection seeding with two seed frequencies. We show that the relative energy in the two frequency components can be adjusted by varying the relative seed power, and that they have excellent spatial, angular, and temporal overlap. The result is a deeply modulated 1.06-μm pulse with a modulation frequency that can be tuned from 185 MHz to at least 17 GHz in 185 MHz increments. In addition to the two seeded frequencies, weak sidebands are also observed in the output spectra. Their energy content is typically less than 1% of that of the seeded modes. We discuss mechanisms which might cause them     

衍射极限的掺钕钇铝石榴石激光器

本文报导一种以掺钕钇铝石榴石为工作物质的激光器,其输出光束达衍射极限。输出脉宽为6～7毫微秒(FWHM),光谱宽度约为0.35埃(FWHM),最高输出达60毫焦耳,偏振度达98％,重复率为1次/秒。激光谐振腔采用平凸非稳定腔结构。     

Single-diode end-pumped Nd:YAG laser

Experimental results on the first miniature Nd:YAG laser end-pumped by a single incoherent infrared-emitting diode are given. Laser operation was verified by measurements of relaxation oscillations, angular divergence, wavelength, and nonlinear output. In order to emit in the 0.81- μm pump band of Nd:YAG, the GaAs1-xPxdiode required cooling to 88 K (-185°C). Cooling the diode increased its efficiency while cooling the rod decreased the pump power necessary to reach threshold. With both laser mirrors highly reflecting at 1.06 μm, the maximum pulse powerP_{D}^{th}emitted by the diode at threshold was 6.2 ± 1.2 mW. The diode power required for laser threshold at room temperature was derived and compared with more recent experiments. Miniature size and long-lived solid-state components make this laser attractive for further development.     

二极管端泵浦Nd：YAG连续激光器

我们研制了一台二极管连续端泵浦的Ｎｄ：ＹＡＧ激光器，用国产激光二极管作泵浦源，泵浦激光波长为０．８０８μｍ。激光介质为φ５×５ｍｍ的Ｎｄ：ＹＡＧ棒，输出激光波长为１．０６μｍ，用ＣＣＤ相机和图象处理系统记录和分析激光光斑，得到激光横模为ＴＥＭ００模，当输入谐振腔的泵浦功率为２２５ｍＷ时，输出连续激光功率最高达７６．４ｍＷ，光－光转移效率为３３．９％，电光斜效率达到９．１％，并做了腔外倍频实验。     

板条型脉冲Nd∶YAG激光器的研究

本文研制了尺寸为124×12×6mm~3的Nd:YAG晶体板条型脉冲激光器,自由振荡单脉冲输出24J,器件总体效率2.5％,电光调Q单脉冲输出860mJ,脉宽12～15ns,Q开关效率72％。     

Nd:YAG laser pumped infrared dye laser

Efficient operation of a high peak power and high-average power infrared dye laser, continuously tunable over the range of 10810-12160 Å, has been achieved by pumping with an Nd:YAG laser. A peak power as high as 4 MW with an average power of 390 MW was obtained.     

C r^4＋：YAG被动Q开关的Nd：YAG激光器

本文以Ｃｒ＾４＋：ＹＡＧ作可饱和吸收材料，研究了高效率的灯泵单脉冲被动Ｑ开关Ｎｄ：ＹＡＧ激光，单脉冲Ｑ开关的输出为５０－７０ｍＪ，Ｑ开关效率为４６％－５２％，总效率为０．７５％－０．９７％，脉冲宽度（ＦＷＨＭ）为７－９ｎｓ。     

YAG:Nd~(3 )晶体光学均匀性对激光性能测试的影响

在进行N4~(3 ):YAG激光晶体性能测试过程中,常常发现同一根晶体棒在相同的实验条件下于谐振腔内旋转不同角度时可得到不同的实验数值(例如在测定脉冲效率、连续效率、内耗时)。我们考虑这是由于激光棒的不均匀性引起的。     

FM-laser operation of the Nd:YAG laser

The FM-laser or frequency-sweeping mode of laser oscillation has been demonstrated in a Nd :YAG 1.06-μ laser with an intracavity LiNbO3phase modulator. The experimental results are in excellent agreement with the theoretical expressionDelta= (DeltaOmega/Deltanu) (delta/pi)where δ= peak single-pass phase retardation in the modulator,DeltaOmega= axial mode spacing,Deltanu=modulator detuning, and Δ=resulting FM index of the laser output. Modulation indices as large asDelta approx 230rad have been obtained, in which case the instantaneous laser frequency is sweeping over a full spectral range of2Delta cdot f_{m} approx 120GHz (≈ 4 cm^-1) at a repetition frequencyf_{m} approx 260MHz, with a time-bandwidth product per periodapprox 2Delta approx 460. The coherently mode-locked spectral bandwidth thus obtained in the FM-laser case is very much wider than can be achieved in the pulsed mode-locked case with the same Nd:YAG laser. Some possible ways of using this broad-band coherent FM spectrum are suggested.     

脉冲稳频Nd∶YAG环行激光器

我们在实现单频行波运转的脉冲Nd∶YAG环行激光器基础上,通过自动搜索补偿和快速稳频环路,获得脉宽为0.7ms,峰值功率大于100W,频漂小于1MHz的1.06μm稳频激光。     

Q开关Nd:YAG激光切割晶体后囊膜

自从1980年Aron-Rosa报道第一篇“应用Nd:YAG激光打开人工晶体植入后的后囊膜”的论文后,引起眼科界很大的反响.在这以前,主要利用眼球色素组织吸收可见光,产生热效应达到光凝固的作用.而调Q-Nd:YAG激光是不可见的近红外光,是由于它的高功率密度,对眼内无色素的半透明或白色组织如晶体囊膜或机化膜进行光学击穿而达到切割组织的作用.我院自1985年10月开始应用于临床.     

LED带抽运Nd∶YAG激光器

为了研究抽运光源光谱与增益介质吸收光谱对发光二极管(LED)带抽运激光器输出效率的影响,进一步提高输出效率,将光谱信息引入激光速率方程中,建立了LED带抽运速率方程, 采用该方法对LED带抽运Nd∶YAG激光器进行了理论分析和实验验证。结果表明,利用红外LED对Nd∶YAG激光器进行侧面抽运,当抽运能量为9.1mJ时,取得了能量为607μJ的1064nm激光输出,达到实验中最高的倾斜效率15.5%,此时光转换效率为6.67%;速率方程的计算求解和实验的输出能量二者基本吻合。这一结果对研究提高LED带抽运激光器的输出效率是有帮助的。     

Stabilized efficient single-frequency Nd:YAG laser

It is shown how intracavity etalons can be optimally designed for axial mode selection and frequency stabilization of gas and crystal lasers. Relevant laser parameters, required etalon properties, and expected losses are determined. A simple frequency stabilization scheme based on birefringent etalons is described, which does not require laser modulation. Major problems associated with stable single-frequency operation of solid-state lasers are discussed. Using an optimally designed crystal quartz etalon, a Nd:YAG laser could be stabilized to 10^-7in frequency and 2 percent in amplitude. The linearly polarized single frequency TEM00output was 150 mW, which compares to an unpolarized 12-mode output of 400 mW for the bare laser.     

以砷化镓为锁模元件的被动锁模Nd:YAG激光器

报道以厚400μm、(100)向的砷化镓替代染料为锁模元件的全固态被动锁模Nd:YAG激光器。锁模脉冲宽度为16ps,单脉冲平均能量10μJ,锁模几率大于90％。     

Harmonic mode locking of the Nd:YAG laser

We present experimental and theoretical results forNth harmonic mode locking of a Nd:YAG laser with an intracavity phase modulator operating atN = 2, 3, 4,and 5 times the fundamentalc/2Lfrequency. The bandwidths of the resulting mode-locked spectra depend upon modulation frequency, modulation depth, and laser cavity losses in good agreement with the Gaussian-pulse analysis of Kuizenga and Siegman [5]. For modulation atN(c/2L)the resulting pulse-repetition frequency is alsoN(c/2L)in all cases. However, in theN = 2case, for example, the mode-locked optical spectrum includes every adjacent axial mode component if the laser rod is located near the center of the laser cavity, but only every other axial mode when the rod is located at the end of the laser cavity. This behavior is explained by a Lamb-type theoretical analysis taking into account the competition between the two "hypermodes," or sets of interleaved next-adjacent axial modes, that can oscillate separately or simultaneously in theN = 2case.