Discharge lasers pumped by generators with inductive energy storage

Generators with inductive energy storage units and semiconductor opening switches designed for laser excitation are described. Operation of the generators on a gas-discharge load is considered and possible excitation modes are discussed. A longitudinal N₂ laser, transverse discharge nonchain HF laser, and CO₂ laser are developed based on this pumping technique. Output energies of 0.6 J and 3.2 J and laser efficiencies of 5.5% and over 17% were demonstrated on H ₂-SF₆ and He-CO₂-N₂ gas mixtures, respectively. High laser parameters obtained demonstrate the considerable promise of such inductive generators for pumping different gas lasers     

Compact solid-State switched pulsed power and its applications

Power semiconductor devices, such as insulated-gate bipolar transistors, metal-oxide-semiconductor field-effect transistors, and static-induction thyristors, are used in different kinds of pulsed power generators developed for different applications. In addition, the semiconductor opening switch is found to have very effective applications in pulsed power generation by inductive energy storage. Semiconductor switches have greatly extended the scales of pulsed power parameters, especially in repetition rate and lifetime. They have also enabled new areas of pulsed power applications, such as accelerators, flue-gas treatment, and gas lasers.     

Generators of High-Amplitude Ultrashort Pulses with a Trailing-Edge Shaper

Journal of Communications Technology and Electronics - Operation of ultrashort pulse generator based on an inductive energy storage and semiconductor opening switch (diode with charge storage) is...     

Effect of xenon on the gas temperature in carbon monoxide lasers

By experimentally measuring the gas temperature of a discharge in CO-He-(Xe) laser gas mixtures it is established that the advantageous effect of the addition of xenon in > 10 percent efficient room temperature lasers is not a gas temperature effect.     

Telecom-Wavelength Organic Single-Crystal Lasers Triggered by the Molecular Conformation-Dependent Cascaded Proton Transfer Processes

Organic semiconductor molecules possess chemical tunability and large stimulated emission cross section, representing a promising candidate for laser gain medium. However, for the pursuit of telecom-wavelength organic lasers, one of the major obstacles is the lack of effective energy-level systems with high optical gain to compensate the exciton deactivation losses. Herein, the effects of molecular conformation-dependent distinct cascaded proton-transfer six-level energy gain systems on lasing emission properties are systematically investigated based on organic polymorphs, proving that an energy-level gain system without reversible transition channels is more conducive to the formation of efficient population inversion and high optical gain. Notably, the one-way irreversible six-level energy system of β-phase polymorph supports more favorable population inversions than the two-way reversible six-level system of α-phase polymorph due to the irreversible excited-state second proton transfer and the irreversible ground-state recovery, achieving the amplified spontaneous emission at telecom-wavelength of ≈850 nm. This study provides useful guidelines for constructing efficient energy-level gain systems, promoting the exploration of high-gain organic semiconductor laser materials from visible to near-infrared region.     

放电单重氧发生器的研究进展

氧碘激光器主要是通过O2(1△)与碘原子的共振能量转移来实现的,用气体放电的方法产生O2(1△)是目前的研究热点.介绍了各种放电单重氧发生器的结构特点以及存在的问题.射频放电由于具有较好的稳定性以及均匀性,已经广泛用于各种气体激光器的激励.     

Superior High-Temperature Energy Density in Molecular Semiconductor/Polymer All-Organic Composites

High-temperature dielectric polymers are in constant demand for the multitude of high-power electronic devices employed in hybrid vehicles, grid-connected photovoltaic and wind power generation, to name a few. There is still a lack, however, of dielectric polymers that can work at high temperature (> 150 °C). Herein, a series of all-organic dielectric polymer composites have been fabricated by blending the n-type molecular semiconductor 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) with polyetherimide (PEI). Electron traps are created by the introduction of trace amounts of n-type small molecule semiconductor NTCDA into PEI, which effectively reduces the leakage current and improves the breakdown strength and energy storage properties of the composite at high temperature. Especially, excellent energy storage performance is achieved in 0.5 vol.% NTCDA/PEI at the high temperatures of 150 and 200 °C, e.g., ultrahigh discharge energy density of 5.1 J cm⁻³ at 150 °C and 3.2 J cm⁻³ at 200 °C with high discharge efficiency of 85–90%, which is superior to its state-of-the-art counterparts. This study provides a facile and effective strategy for the design of high-temperature dielectric polymers for advanced electronic and electrical systems.     

100 J侧面滑闪预电离TE CO2激光器

提出了一种新型侧面滑闪放电技术,为TE CO2激光器均匀放电提供高效、均匀的紫外预电离。采用这种技术,成功实现5.5 cm电极间距的高气压CO2均匀放电,放电截面达27.5 cm2。放电体积为5.5 cm×5 cm×90 cm的单元模块采用V(CO2)∶V(N2)∶V(He)=1∶1∶4的混合气体在60 kPa的气压下,获得了53 J的激光脉冲输出,激光比输出能量达3.46×10-4J/(L.Pa)。采用简单的谐振腔,利用两个相同的单元模块串联实现了103 J的激光输出。实验表明双模块器件存在很强的激光脉冲能量增强效应,双模块串联输出的激光能量比单模块激光能量的两倍还大15%。     

Efficient E-beam excitation of XeCl

Efficient laser output at 308 nm has been obtained from XeCl in an Ne/Xe/HCl mixture at a pressure of 4 atm bye-beam excitation and bye-beam controlled discharge pumping. Maximum energy extraction is 7 J/1 fore-beam excitation and 9 J/1 for thee-beam controlled discharge. Efficiencies based on total energy deposited in the gas are approximately 4 percent. Similar results were obtained with KrF in the same device, indicating that undere-beam ore-beam controlled discharge excitation, XeCl may be as efficient as KrF.     

千瓦级横流连续CO2激光器流场特性的研究

本文针对MGL-84型千瓦级横流CO2激光器,深入研究了流场气动特性对激光放电的影响,提出了使流场速度分布更加均匀的措施,所设计的湍流发生器明显地改善了放电稳定性。     

Bessel beams from semiconductor light sources

We report on recent progress in the generation of non-diffracting (Bessel) beams from semiconductor light sources including both edge-emitting and surface-emitting semiconductor lasers as well as light-emitting diodes (LEDs). Bessel beams at the power level of Watts with central lobe diameters of a few to tens of micrometers were achieved from compact and highly efficient lasers. The practicality of reducing the central lobe size of the Bessel beam generated with high-power broad-stripe semiconductor lasers and LEDs to a level unachievable by means of traditional focusing has been demonstrated. We also discuss an approach to exceed the limit of power density for the focusing of radiation with high beam propagation parameter M². Finally, we consider the potential of the semiconductor lasers for applications in optical trapping/tweezing and the perspectives to replace their gas and solid-state laser counterparts for a range of implementations in optical manipulation towards lab-on-chip configurations.     

TDLAS技术气体检测二次谐波信号的仿真与分析

可调谐半导体激光吸收光谱(TDLAS)技术结合半导体激光器可调谐的特点及气体分子对特定波长能量光的吸收特性,凭借灵敏度高、响应时间短等优势广泛应用于气体浓度检测。TDLAS技术气体浓度检测包括波长调制、气体吸收、二次谐波解调等环节,吸收信号的二次谐波分量携带气体浓度信息,用于计算气体浓度。利用MATLAB对气体检测过程进行了信号仿真,并利用数字锁相放大算法提取了二次谐波信号,验证了二次谐波与气体浓度的关系。通过仿真分析了二次谐波信号随调制系数的变化关系,以便确定较佳的调制参数,为后续系统搭建与气体检测实验提供参考。     

气体激光器的微波激励技术

作为一种优良的气体激光器的激励技术——微波激励技术,已成功地用于多种辉光放电形式的脉冲和连续波气体激光器中,其中包括原子、分子和准分子激光器,并已进入实用化阶段。本文评述这种激励技术的进展。     

Recent progress in the development of electrically and optically pumped dye vapor lasers

This paper reviews new results in the field of organic dye vapor lasers. Gain studies of the scintillator dye POPOP in liquid solution and in the vapor phase show that a dye vapor exhibits optical gain nearly as high as in the solution case under excitation by a N2laser. Superradiant emission has been observed from both, optically excited POPOP vapor and electron-beam excited vapor. The optimum operating conditions of an electron-beam pumped dye vapor-buffer gas system with high purity argon as buffer are reported. Potential energy transfer processes from the rare-gas buffer to the dye vapor are discussed. The metastable ionic species Ar+2has been identified as the most likely POPOP excitation source after intense electron pumping of the dense Ar buffer gas at typically 4-5 atm. An estimate of the conversion efficiency from electronic energy deposited in the Ar buffer to stimulated emission of the dye yields 5 percent. These results suggest that an efficient tunable electron beam pumped dye vapor laser is feasible.     

RF-pumped infrared laser using transverse gas flow

A transverse gas flow configuration has been developed utilizing RF discharge waveguide technology for several infrared lasers. Two potential applications have been identified: pulsed chemical laser and CW CO2laser. In the 3.8 μm DF laser, the flowing gas device provides rapid gas replenishment to maintain high electrical efficiency at high repetition rates. An average power of 0.6 W was achieved at 1 kHz. An order of magnitude power improvement can potentially be developed in a closed cycle system. In the CW CO2laser, the flowing gas provides efficient cooling so that high output power per unit gain length can be achieved. A 16 W output in a 20 cm gain length device, corresponding to a record 0.8 W/cm output has been demonstrated. This system can be developed into a 20-60 W laser with a 20-50 cm gain length.     

Simulink仿真指导放电准分子激光长脉宽的实验探究

针对医疗用308 nm准分子激光器长脉宽的实际需求,提出Simulink仿真模型指导延长激光脉宽的方案,并进行实验研究。首先建立并验证了典型准分子激光器放电激励回路仿真模型的有效性,其次基于脉冲形成网络原理建立4级LC峰化回路的放电激励模型,并进行了具体的激光器结构设计和参数选择。对一台储能电容为60 nF,工作电压范围在20~29 kV的308 nm准分子激光器进行实验,通过改变激励回路的结构和参数,激光脉宽由30 ns延长到60 ns,且当储能电容电压值为28 kV时,输出能量达407 mJ,激光脉冲能量的转移效率由典型结构的1.531%提高至1.73%,实现了放电激励308 nm准分子激光长脉冲输出条件下的高能量转移率,验证了Simulink仿真模型的有效性和指导意义,为实用化长脉宽准分子激光的设计和应用提供基础。     

大能量高功率准分子激光的应用及关键技术

实用型大能量高功率准分子激光器广泛地应用于材料的加工及表面处理,介绍了其在液晶平板显示行业、太阳能光伏行业、半导体行业及汽车制造业的应用。分析了大能量高功率准分子激光器的关键技术,如大面积均匀放电技术,预电离技术,高压快脉冲激励技术以及为了得到更大的脉冲能量及功率输出而采用的双腔同步技术。     

长脉冲紫外预电离TE CO2激光器

研制了一台增益体积为1.17 L的长脉冲紫外预电离TE CO2激光器。基于Pulser/sustainer技术,设计了独立可控的双高压开关抽运电路。在激光混合气体比CO2∶N2∶He=1∶2.5∶13,总气压30 kPa时,以6 nF的Pulser电容控制100 nF的Sustainer电容,获得稳定的辉光放电,激光比注入能量达1.607 J/(kPa.L),其中,Pulser能量不到全部注入能量的5%。另外,在保持Sustainer总电容100 nF不变的情况下,设计了两种脉冲宽度略有不同的Sustainer电路,均获得了稳定的辉光放电,实验测量了放电电压、放电电流与输出激光脉冲波形,并分析了Sustainer放电的阻抗特点。激光器采用“Z”形折叠腔结构,输出激光脉冲宽度达20μs,电光转换效率超过12.0%,最大脉冲能量为6.5 J。     

Computational model of longitudinal discharge uniformity inRF-excited CO2 slab lasers

A computational model is used to predict longitudinal excitation uniformity in large-area electrodes for RF-excited CO₂ lasers. Effects of nonuniform discharge loading along the electrode transmission line are accounted for in the model, as is the dependence of discharge properties on power loading, excitation frequency, gas pressure, and electrode geometry. Predictions of excitation uniformity are tested against measurements of discharge luminosity. Good agreement is demonstrated. Since the model is valid over the range of discharge conditions interesting to slab CO₂ lasers, it should applicable to the problem of slab electrode optimization     

高功率高重频TEA CO_2激光器均匀场放电电极设计

介绍了在高功率、高重频TEACO2激光器上应用的修整改型Chang氏电极的结构形状。对修整改型的Chang氏电极在垂直放电方向上有较好的均匀性、电极的曲面、电极表面电场强度分布、主放电极辉光放电和放电区域均匀放电做了必要的论述。通过电极型面及结构的基本放电参数与输出特性的实验,并结合在大功率、高重频、高脉冲能量和高速气体循环特点下的TEACO2激光器,说明选择修整改型后的Chang氏电极更为适宜。