毛细管放电激励软x射线激光的产生时间

利用x射线二极管(XRD)，实验上测量了毛细管放电激励下类氖氩469nm软x射线激光的尖 峰信号. 改变毛细管的充气气压和主脉冲放电电流，研究了激光尖峰的产生时间随实验参数 的变化情况. 实验结果表明，激光产生于主脉冲电流波形的前沿，此时的主脉冲电流是其峰 值的65%—75%. 增加毛细管充气气压或者减小主脉冲峰值电流，激光的产生时间将会稍有延 迟. 同时改变毛细管充气气压时，激光尖峰信号在42Pa存在最大值. 关键词： 毛细管放电 软x射线激光 激光产生时间     

Combined weak-current discharge in a copper-vapor laser

We have considered the application of a new method of pumping of active media on metal vapors by a combined weak-current discharge. A distinguishing feature of a weak-current discharge compared to the method for the traditional pumping of self-contained lasers is the regime of lower energy input to the discharge. Using this regime, it is possible to realize a pulsed-periodic form of the discharge with laser pulses of various shapes and durations at low current amplitudes (several amperes). Additional pulsed-periodic discharge is used to heat the active zone.     

Capillary discharge soft X-ray lasing in Ne-like Ar pumped by low main current pulses

Under the condition of the low main current pulse, the capillary discharge soft X-ray laser is obtained. The laser energy of the same discharge current amplitude at different Ar pressures and of different current amplitudes at the same Ar pressure are compared, respectively. At different Ar pressures, the amplitude of the main current pulse evidently impacts the soft X ray, especially at a pressure higher than 30 Pa. In order to obtain the laser output at a high Ar pressure, the amplitude should be increased. However, at the same Ar pressure, it might have an optimum current, in which case the laser spike is the highest and the most stationary. The laser achieving time at different amplitudes is also discussed. As far as we know, this is the first time the influence of the amplitude of the main current pulse has been analyzed.     

高光束质量Nd:YAG激光系统的研制

针对惯性约束核聚变驱动器激光预处理系统的需求,研制了一套高功率高光束质量Nd：YAG 激光系统,该系统中采用了高稳定的被动调Q单纵模振荡器、受激布里渊散射脉冲压缩和高效聚光腔等多种技术,获得了脉冲宽度3ns、激光能量1.1J、远场发散角0.3mrad的激光输出。     

High power high repetition rate pulsed collisional laser using a He + Eu+ mixture

Studies have been made of the properties of an ionized europium collision laser with=1002 nm in the 1.5 to 6 kW range of pumping powers. For this purpose, a gas-discharge tube made of BeO ceramic, 50 cm long and 2.7 cm diameter was used. The pulse repetition rate ranged from 2 to 10 kHz at a pumping duration of 400 ns.For helium pressures in the range of 0.3 to 1 atm, the efficiency and laser power increases faster than the concentration of helium atoms. At the atmospheric pressure of helium, the optimal lasing conditions are as follows: discharge current amplitude 150 A, the europium vapour pressure corresponds to 640 to 660° C and is dependent on the discharge current. The laser efficiency is independent of the pulse repetition rate in the 3 to 9 kHz range.The maximum laser power achieved was 12.7 W atF=9.5 kHz, and the efficiency amounted to 0.21%, whereas at 11.8 W andF=6.5 kHz the maximum efficiency was 0.24%. The dynamic efficiency of the laser reached 0.4%.     

高光束质量Nd:YAG激光系统的研制

 针对惯性约束核聚变驱动器激光预处理系统的需求,研制了一套高功率高光束质量Nd：YAG 激光系统,该系统中采用了高稳定的被动调Q单纵模振荡器、受激布里渊散射脉冲压缩和高效聚光腔等多种技术,获得了脉冲宽度3ns、激光能量1.1J、远场发散角0.3mrad的激光输出。     

Effect of leakage transformer on laser power and mode pattern of CO2 laser excited by 60 Hz AC discharges

The 60 Hz AC discharges generated by a leakage transformer instead of an isolation one, which is usually used in the power supply of DC CO₂ laser, are employed as a pumping source in this experiment. The laser performance characteristics as functions of pressure and discharge current have been investigated. The maximum laser power is about 40 W at conditions of 18 Torr and 35 mA. The output power is not less than that of DC discharge at the same condition. In addition, the laser outputs of 60 Hz AC discharges obtained by different transformers such as a leakage type and an isolation one have been measured. It was found that the laser power obtained by the leakage transformer is saturated at the higher current compared with the isolation transformer.     

毛细管放电X光激光装置中的预脉冲电源

 针对目前毛细管放电X 光激光装置产生的预脉冲电流幅值过大、持续时间较短的问题，提出了增加预脉冲开关抑制原有预脉冲，再外加由脉冲成形网络组成的预脉冲发生器，产生所需预脉冲的改造方案。可在主脉冲来临之前产生幅度10~50A，持续时间约17μs的方波预脉冲电流，来满足毛细管放电泵浦类氖氩X光激光实验的需要。     

用于XeF蓝绿激光器的表面放电光泵浦源

基于Al2O3陶瓷、BN陶瓷和聚四氟乙烯三种基底建立了分段表面放电光泵浦源,对比研究了这三种表面放电光泵浦源的电学特性、辐射特性和烧蚀特性。利用放电波形计算了表面放电光泵浦源的等效电感、等效电阻和沉积效率,应用光谱法比较了它们的紫外辐射强度,并采用平均线烧蚀率评估了三种泵浦源的耐烧蚀性能。通过比较研究发现,在充电电压为13.5～26.8 kV、间隙长度为8 cm、放电室内混合气体气压为100 kPa条件下,三种泵浦源中 Al2O3陶瓷表面放电光泵浦源的沉积效率最高,大于82%;辐射光谱具有紫外增强效应,紫外辐射最强;平均线烧蚀率最小(小于0.15 m/shot),耐烧蚀性能最好。研究结果表明采用Al2O3陶瓷表面放电光泵浦源作为大功率重频XeF蓝绿激光器的泵浦源,可提高XeF蓝绿激光器的寿命。     

用于XeF蓝绿激光器的表面放电光泵浦源

基于Al2O3陶瓷、BN陶瓷和聚四氟乙烯三种基底建立了分段表面放电光泵浦源,对比研究了这三种表面放电光泵浦源的电学特性、辐射特性和烧蚀特性。利用放电波形计算了表面放电光泵浦源的等效电感、等效电阻和沉积效率,应用光谱法比较了它们的紫外辐射强度,并采用平均线烧蚀率评估了三种泵浦源的耐烧蚀性能。通过比较研究发现,在充电电压为13.5~26.8kV、间隙长度为8cm、放电室内混合气体气压为100kPa条件下,三种泵浦源中Al2O3陶瓷表面放电光泵浦源的沉积效率最高,大于82%;辐射光谱具有紫外增强效应,紫外辐射最强;平均线烧蚀率最小(小于0.15μm/shot),耐烧蚀性能最好。研究结果表明采用Al2O3陶瓷表面放电光泵浦源作为大功率重频XeF蓝绿激光器的泵浦源,可提高XeF蓝绿激光器的寿命。     

毛细管放电X光激光装置中的预脉冲电源

针对目前毛细管放电X 光激光装置产生的预脉冲电流幅值过大、持续时间较短的问题,提出了增加预脉冲开关抑制原有预脉冲,再外加由脉冲成形网络组成的预脉冲发生器,产生所需预脉冲的改造方案。可在主脉冲来临之前产生幅度10~50A,持续时间约17μs的方波预脉冲电流,来满足毛细管放电泵浦类氖氩X光激光实验的需要。     

High power repetitive TEA CO2 pulsed laser

A high power repetitive spark-pin UV-preionized TEA CO₂ laser system is presented. The discharge for generating laser pulses is controlled by a rotary spark switch and a high voltage pulsed trigger. Uniform glow discharge between two symmetrical Chang-electrodes is realized by using an auto-inversion circuit. A couple of high power axial-flow fans with the maximum wind speed of 80 m/s are used for gas exchange between the electrodes. At a repetitive operation, the maximum average output laser power of 10.4 kW 10.6 ??m laser is obtained at 300 Hz, with an electro-optical conversion efficiency of 15.6%. At single pulsed operation, more pumping energy and higher gases pressures can be injected, and the maximum output laser energy of 53 J is achieved.     

Effect of optical pumping of metastable helium atoms on the operation of a helium-neon laser

Nonradiative destruction of the upper levels of helium has made possible optical pumping of metastable 2³S He atoms in a helium-neon laser. The changes in gain under various discharge conditions have been determined by introducing an extra loss, which has produced the same drop in generated power as extra pumping from a helium tube. The lifetime of the metastable 2³S He atoms has been measured as a function of the discharge current under a specific set of conditions.     

低温Yb:YAG放大器增益与热畸变特性实验研究

为了研究低温条件下Yb:YAG放大器的增益和热特性,搭建了一套液氮冷却的低温放大器,开展了实验研究。测量了不同泵浦强度下的小信号增益以及低温和常温下的介质热致波前畸变。结果表明:低温条件下,可以用更少的泵浦能量得到高于常温的增益;常温下泵浦电流200A、脉冲宽度1200μs的小信号增益为1.59;低温下泵浦电流200A、脉冲宽度400μs的小信号增益为1.82,光光效率显著提高。自发辐射放大(ASE)问题在低温下更加显著,采用短脉冲泵浦有利于降低ASE的影响。低温的热管理效果较常温有显著提高,可以在更高的平均功率下运行。     

Generation and amplification of sub-picosecond pulses using a frequency-doubled neodymium YAG pumping source

Stable, tunable, sub-picosecond pulses have been obtained by synchronously pumping a Rhodamine 6G dye laser with a frequency-doubled CW modelocked neodymium YAG laser. Careful attention has been paid to minimize amplitude and timing instabilities, resulting in dye laser pulses shorter than 500 fs. The main advantage of this new pumping source over current synchronously pumped dye lasers is that it is particularly well suited to short pulse amplification. Using this technique amplification of 2 × 10⁶ has been achieved.     

LD 泵浦的Cr4+:Nd3+:YAG自调Q激光器研究

利用4W的激光二极管泵浦Cr4+:Nd3+:YAG微片,获得了自调Q激光脉冲输出。在连续泵浦状态下,获得重复频率为10KHz脉冲宽度为40ns调Q脉冲激光输出。在脉冲泵浦状态下,获得包含多个子脉冲的脉冲序激光输出。采用加基电流的矩形脉冲泵浦,获得了稳定的单脉冲输出。     

星光Ⅱ装置激光能量测量实时采集和数据传输系统

介绍一套激光能量实时采集和多路传输通信系统。该系统兼容现有的不同型号和规格的激光能量计,具有峰值保持和功率积分功能,抗干扰能力强,可实现数据自动采集、处理及长距离多点传送。为实现激光能量测量精密化和自动化打下了技术基础。     

Time delay in InGaN multiple quantum well laser diodes at room temperature

This paper reports that a long delay between the beginning of pumping current pulse and the onset of optical pulse is observed in InGaN laser diodes.The delay time decreases as the pumping current increases,and the speed of the delay time reduction becomes slower as the current amplitude increases further.Such delay phenomena are remarkably less serious in laser diodes grown on GaN substrate than those on sapphire.It attributes the delay to the traps which cause a large optical loss by saturable absorption and retard the laser action.The traps can be bleached by capturing injected carriers.The effect of GaAs laser irradiation on InGaN laser action demonstrates that the traps responsible for the delay are deep centres which can be filled by the photo-assisted processes.     

Sättigungsverhalten und Verlauf der Elektronentemperatur beim Argon-Ionenlaser

Recently saturation of laser power ofCW ion lasers has been observed with large bored laser tubes made of metal segments. The saturation was observed in Argon, Krypton and Xenon in high current regions. In this case it was necessary to calculate the correlation between the electron temperature, electron- and ion-density and on the other hand the discharge quantities as current density and voltage drop. By measuring the discharge quantities at optimum laser power it is possible to determine the optimum electron temperature for any current density. The comparison of the run of these quantities leads to the assumption that the saturation mechanism causes a decrease of the optimum electron temperature.     

Magnetization dynamics in epitaxial films induced by femtosecond optical pulses near the absorption edge

Peculiarities of the magnetization dynamics induced in iron garnet films by laser pulses with a frequency detuning near the absorption edge have been studied experimentally. It has been found that the dependence of the observed signal amplitude on the pumping energy becomes nonmonotonic with an increase in the pumping frequency. At the same time, the pumping energy corresponding to the maximum amplitude of the signal and this maximum signal amplitude decrease. Moreover, the signal amplitude starts to decrease with an increase in the pumping energy at frequencies within the absorption band. The observed phenomena are possibly caused by generation of magnetostatic spin waves and the effect of ultrafast optically induced demagnetization.