紫外可调频准分子激光系统

报道一种结构简单的紫外可调频放电泵浦准分子激光系统,只用一个火花隙控制两台准分子激光器实现了振荡放大。在XeCl(中心波长308毫微米)谱区实现了调频输出,单脉冲能量11毫焦耳,带宽0.07毫微米,束散角约为0.2毫弧度。     

准分子激光光束均匀技术

由于放电结构及谐振腔的限制,准分子激光光斑呈现不均的分布。介绍了各种均匀器的工作原理,从衡量光束均匀性的各项指标出发,评述分析了各种均匀方法的优缺点及适用范围。     

紫外激光切割Si片的实验研究

报道了用193nm准分子激光切割硅片的实验结果。采用柱透镜光学系统及“热劈裂法”获得小于15μm的切缝及小于5μm的切面不平整度。     

New wavelengths of the YAlO3: Er laser

In addition to the 1.662 μm laser transition, stimulated emission at three new wavelengths at 1.677, 1.706, and 1.729μm have been observed at 300 K in the YAlO3:Er crystal with an activator concentration of 1.25 weight percent.     

CH4受激拉曼散射产生紫外激光用于NO2差分吸收激光雷达的研究

脉冲Nd:YAG三倍频激光(355 nm)泵浦CH4的受激拉曼散射第一级斯托克斯光(395.6 nm)用作NO2差分吸收激光雷达的λon.为研究CH4的受激拉曼散射效应和定量解释其物理机理作了数值模拟计算,并作了一系列的实验.通过调节泵浦能量、光束质量和气体压强,得到了各级散射光的能量转化效率与三者间的函数关系,找到了第一级斯托克斯光的优化条件.     

紫外预电离Blumlein型准分子激光器放电特性-能量耦合关系

介绍了用上升时间为0.8毫微秒,耐压为60千伏的一组分压器和磁光法,研究紫外预电离Blumlein直型准分子器件能量耦合过程的结果;最后对最佳耦合形式等问题进行了讨论。     

New UV laser transitions of sulfur and oxygen

Three new UV laser lines, S III 363.2 nm and O II 397.3 and 398.3 nm, obtained by means of an axial pulse discharge, are reported.     

Even-and odd-mode guide wavelengths of coupled lines in microstrip

Measurements have been made of the even- and odd-mode guide wavelengths of coupled microstrip lines on alumina between 1 and 12 GHz. Both modes show a linear relationship of negative slope between normalised wavelength and frequency.     

Biological effects of excimer laser radiation

Excimer laser radiation at 193 nm (ArF) and 308 nm (XeCl) is being used for medical applications. Because ultraviolet radiation is absorbed by DNA and causes cell killing, mutagenesis, and carcinogenesis, the effects of 193- and 308-nm excimer laser radiation on biological material have been studied. Radiation at 193 nm causes less cell killing than conventional 254 nm germicidal light per incident photon. Radiation at 193 nm showed very low potential for causing mutation because proteins absorb strongly at 193 nm, thereby reducing the photon flux reaching the nuclear DNA. In addition, the quantum yield of a cytotoxic and mutagenic photoproduct of DNA is lower for 193 nm than for 254 nm. Radiation at 308 nm is cytotoxic and mutagenic. Results of in vitro assays indicate that the relative ability of excimer laser radiation to cause DNA damage decreases in the order 248 nm>308 nm>193 nm     

准分子激光离体血管成形术

用波长308nm的XeCl准分子激光照射试管内及离体动脉內血栓和主动脉壁,经目视观察及组织学检查表明:准分子激光能有效地汽化血栓;若保持激光与血管同轴,则可避免损伤血管壁;准分子激光照射血管壁形成的切割边缘整齐,组织学上无热损伤现象。因而准分子激光可以安全有效地应用于血管成形术。     

强激光脉冲序列SRS效应的理论研究

本文从理论上给出了脉冲序列受激喇曼散射(SRS)效应中斯托克斯光脉冲的场增益公式。结果表明序列的各脉冲前沿存在斯托克斯光增益;在一定脉冲结构和光强下,介质记忆效应占主导地位。     

光刻用准分子激光器中心波长在线测量研究

实现了一种准分子激光光刻光源中心波长的实时测 量方法。基于法布里珀罗(F-P)标准具与中阶梯光栅的相关测量 装置,通过对 F-P标准具的干涉条纹和光栅衍射条纹的分析,实现了对光刻光源输出激光中心波长的在 线有效测量。整 个测量装置体积小、成本低,在500～3000Hz 高重频条件下,实现了亚pm量级的测量精度,标准差低于0.1pm,取 得了较好的实验结果。     

Deep UV exposure of Ag2Se/GeSe2utilizing an excimer laser

Although inorganic resists are characterized by high contrast and resolution, they have traditionally suffered from poor sensitivity. We have investigated the use of a rare-gas halide excimer laser operating at λ = 249 nm to expose the inorganic resist Ag2Se/GeSe2. Well-controlled lines and spaces, each of 0.5-µm width, were contact printed using a chromium-on-quartz mask. By increasing the peak dose rate to about 520 kW/cm², we found that the required dose could be lowered from 130 to 5.2 mJ/cm²; this sensitivity is a factor of 250 better than that obtained with exposures at λ = 436 nm and low power densities. The reciprocity failure at these high flux rates can be explained by a locally induced temperature rise.     

Reciprocity behavior of photoresists in excimer laser lithography

The effect of high excimer-laser peak powers on the lithographic exposure process is quantitatively examined to investigate the reciprocity behavior of several photoresists. Using the bleaching of an absorption peak as the measure of resist response, it is found that there is no dependence of the resist sensitivity on the peak power of the radiation. Thus the higher UV intensity of excimer lasers can be fully exploited in faster exposures of the resists.     

New CW lines from a submillimeter waveguide laser

Sixty-one new CW laser lines with wavelengths between 0.1 and 1.5 mm have been observed with a waveguide laser optically pumped by a CO2laser.     

准分子激光直写二维图形加工

为了探索准分子激光脉冲直写加工的参数和工艺,建立准分子激光微加工系统和材料加工工艺,对二维加工过程中激光刻蚀效果与扫描速度和激光参数之间的关系进行了理论推导,分析表明最大扫描速度受激光光斑尺寸和重复频率的约束.以玻璃为实验靶材,在2.7×1mm2 范围内进行了二维图形刻蚀实验研究.结果显示,刻蚀对材料周围的热影响很小,刻蚀图形清洁而且清晰,通过控制扫描速度可以获得均匀的二维图形.     

New analysis for the assignment of UV-visible ionic Xe laser lines

Visible and UV laser emissions from a highly ionized pulsed Xe plasma were studied in relation to the ionic assignment of the laser lines. Time-resolved spectroscopy and intensity versus pressure analysis were used to determine the ionic origin of the studied lines. The results of both methods show good agreement, and the joint coincidence is used as a criterion for ionic classification, thus imposing a stringent condition for the assignment of the lines and enhancing its reliability. The disagreement between some of our assignments and those from other authors are discussed on the basis of the results of our systematic analysis of more than 200 spontaneous lines in the region of interest     

小型化准分子激光器气体性能的优化

对于新研制的准分子激光系统而言,激光气体的性能具有非常重要的作用,激光系统的混合气体配比与单脉冲能量、放电稳定性和寿命等性能参量有密切关系。为了获得最佳气体配比,在自行研制的小型化Xecl准分子激光器的基础上进行了激光气体性能优化实验,分析了Xe,HCl气体比例对激光性能的影响,通过理论分析和实验结果给出了Ne和He两种不同缓冲气体下的激光性能差异,并给出了该激光系统的优化气体成分和有效提高激光效率方法。实验结果为研制商业化小型准分子激光器件提供了支持和依据。     

New optically pumped FIR laser lines in CD3OH

In this work we report laser action in 69 new FIR laser lines in CD₃OH optically pumped by a regular cw CO₂ laser. We have performed measurements of laser wavelength, optimum pressure of the gas, relative polarization and intensity on all lines, including some previously known.