光抽运XeF(C-A)蓝绿激光器

利用分段表面放电作为光抽运源 ,采用光解离XeF2 技术 ,研制了一台 XeF(C A) 蓝绿激光器。抽运源有效激活长度为 6 0cm ,单位长度的沉积功率为 4 5MW /cm。在 2 5 0PaXeF2 / 6 0kPaAr/ 40kPaN2 条件下 ,采用平凹腔 ,输出耦合为 4% ,获得了XeF(C A)激光输出。对XeF(C A)激光特性参数进行了测量 ,输出能量为百毫焦耳量级 ,最大能量达 16 7mJ,激光脉宽～ 6 0 0ns ,辐射光谱范围 470～ 5 0 0nm ,发散角水平方向为 1 7mrad ,垂直方向为3 7mrad。     

XeF激光与YAG倍频激光对CCD软破坏效应对比实验研究

为了对比研究XeF(C-A)激光和YAG倍频激光对可见光面阵CCD的软破坏效应,分别建立了XeF(C-A)激光和YAG倍频激光对可见光面阵CCD辐照效应实验研究平台和CCD图像同步采集系统,在此基础上开展了上述两种激光对CCD的辐照效应实验,获得了CCD出现局部饱和、全饱和、串音以及全屏饱和时的激光能量密度阈值和CCD图像,并对实验数据进行了总结分析,采用激光能量密度阈值法和饱和面积法对CCD图像进行了分析处理。结果表明,两种激光对SONY SUPER HAD型CCD具有相同的软破坏效应。     

XeF激光器中XeF2气体的监测

给出了一种用吸收光谱法实时监测XeF激光器中XeF2气体压强的方法,标定了XeF2气体在波长为253.7nm处的吸收截面的大小Ó2253.27XeF=(1.55±0.05)×10-19cm2.用该监测系统测量了XeF2气体与3种作为激光器气室材料的反应速率,同时研究了XeF蓝绿激光器中输出激光能量与XeF2气体压强的关系.     

XeF（C-A）蓝绿激光对可见光面阵CCD软损伤的实验研究

建立了脉冲激光辐照CCD器件实验平台,采用XeF（C-A）蓝绿激光辐照可见光CCD,获得CCD出现软损伤（局部饱和、全饱和、串扰及致眩）的激光能量密度阈值或量级及对应的CCD图像,用饱和面积法分析了蓝绿激光对CCD的软损伤效应。     

用于抽运XeF(C-A)激光的分段表面放电辐射源

研制了用于抽运激光的分段表面放电辐射源。辐射源采用分段表面滑闪放电诱导长距离、线性等离子体通道大电流放电 ,实现了高亮度真空紫外辐射 (140～ 170nm) ,且各段总的放电分散时间小于 10 0ns。用该辐射源解离XeF2 获得了XeF (C A)激光输出     

复合物Mg+-S2(CH3)2光解离光谱

在230～440 nm波段,研究了复合物Mg -S2(CH3)2的光解离光谱.此波段内的复合物光诱导产物的质谱揭示,存在着非反应猝灭产物Mg 和反应产物Mg -SCH3.反应产物来源于Mg 离子插入S-S化学键,导致复合物解离的过程.复合物的光解离光谱由三个对应于离子Mg (32P←32S)跃迁的谱峰构成.由量化计算中的CIS方法所获得的吸收谱理论值与实验吻合地较好.     

封闭充气管道中气体热效应对激光传输的影响

对连续激光在封闭充气管道中传输时的热效应进行了数值计算研究,并与实验情况进行了比对。结果表明,在封闭管道环境下,尽管光束传输距离较短,但由于光束能量密度较高、气流不流通,热效应作用将使光束产生较大发散,而且热效应的时间累积影响严重。     

(Ta2O5)0.92(TiO2)0.08介电陶瓷的激光烧结改性研究

采用CO2 激光对 (Ta2 O5) 0 .92 (TiO2 ) 0 .0 8陶瓷的烧结改性进行了系统研究 ,分析了改性微观机理。所制备的陶瓷试样比普通炉烧试样的介电常数值提高了约 3倍 ,平均值约为 4 5 0 ,同时具有良好的热稳定性。通过X射线衍射相结构分析 ,确定激光烧结陶瓷试样中存在H -TiTa18O47高温相 ,采用金相和扫描电镜的分析方法 ,首次获得了陶瓷试样的 3D显微结构信息 ,激光烧结试样具有与普通炉烧试样明显不同的显微结构特征。相结构及显微结构的差异应是激光烧结试样介电性能改善的主要原因。     

CO2激光的大气传输特性

综合分析了影响CO2激光大气传输的一些关键因素,包括大气分子和气溶胶的散射及吸收,与其他波段激光的大气衰减相比较,并对CO2激光的大气传输特性进行了系统的分析与归纳,得出了CO2激光的实际应用性结论.     

NCl(a~1Δ)自猝灭对其生成和传输的影响

利用一维预混合反应模型,对全气相碘激光(AGIL)的储能粒子NCl(a1Δ)的自猝灭反应对其生成和传输的影响进行了模拟计算。计算结果表明,NCl(a1Δ)的自猝灭反应是影响其生成和传输的主要因素;采用最新测得的自猝灭反应常数,NCl(a1Δ)自猝灭反应对其生成和传输的影响程度有大幅度降低,但仍然是主要的影响因素。为了提高NCl(a1Δ)的生成传输效率和准确分析评估AGIL,有必要进一步深入开展NCl(a1Δ)自猝灭常数及其与温度关系的测定工作。     

Controlled Layer Thinning and p‐Type Doping of WSe2 by Vapor XeF2

This report presents a simple and efficient method of layer thinning and p‐type doping of WSe₂ with vapor XeF₂. With this approach, the surface roughness of thinned WSe₂ can be controlled to below 0.7 nm at an etched depth of 100 nm. By selecting appropriate vapor XeF₂ exposure times, 23‐layer and 109‐layer WSe₂ can be thinned down to monolayer and bilayer, respectively. In addition, the etching rate of WSe₂ exhibits a significant dependence on vapor XeF₂ exposure pressure and thus can be tuned easily for thinning or patterning applications. From Raman, photoluminescence, X‐ray photoelectron spectroscopy (XPS), and electrical characterization, a p‐doping effect of WSe₂ induced by vapor XeF₂ treatment is evident. Based on the surface composition analysis with XPS, the causes of the p‐doping effect can be attributed to the presence of substoichiometric WO_x (x < 3) overlayer, trapped reaction product of WF₆, and nonstoichiometric WSe_x (x > 2). Furthermore, the p‐doping level can be controlled by varying XeF₂ exposure time. The thinning and p‐doping of WSe₂ with vapor XeF₂ have the advantages of easy scale‐up, high etching selectivity, excellent controllability, and compatibility with conventional complementary metal‐oxide‐semiconductor fabrication processes, which is promising for applications of building WSe₂ devices with versatile functionalities.     

A 170 J electron beam pumped XeF(C→A) laser

A pulse output energy of 170 J has been achieved from an XeF(C→A) laser system, pumped by a pair of counterpropagating, three-meter-long electron beams. This represents a record for all types of pumping, for this excimer system. Energy was extracted from a volume of ~100 L, using a free-running stable oscillator. No evidence of laser oscillations on the competing XeF(B→X) transition was observed. Within the extraction volume the laser gas was pumped at a rate of 140 kW/cm³ (time average value), for a period of 1.7 μs. The optical cavity was folded, giving a gain length of 6 m. The optical pulse duration was 0.8 μs (full width at half maximum), and the observed flux buildup time of ~1 μs was consistent with modeling and a measurement of the net gain. The specific output energy was 1.7 J/L which is comparable to that achieved in previous, small scale experiments at somewhat higher pump rate. The results confirm the volumetric scalability of the electron beam pumped XeF(C→A) laser system to high output energy per pulse, and the feasibility of operating this system at a low electron beam pump rate which relaxes constraints on the design of the electron gun and pulse power subsystems in a high output energy device. Means for extending the laser pulse duration and increasing the output energy of the specific test device are discussed. An output energy of ~1000 J is projected for an optimized gas cell width, for full size resonator mirrors, and with injection     

Injection-controlled tuning of an electron-beam excited XeF (C→A) laser

Efficient, ultra-narrow spectral output from an electron-beam excited XeF(C rightarrow A) laser medium has been achieved by injection-controlled tuning. Using a pulsed dye laser as the injection source, amplified output pulses tunable between 435 and 535 nm and having a spectral width of 0.001 nm were obtained. For a 482.5 nm injection wavelength that is well matched to the XeF(C rightarrow A) gain maximum, output energy density and intrinsic efficiency values of approximately 8 J/l and 6 percent were achieved.     

Multijoule performance of the photolytically pumped XeF(C→A) laser

An XeF(C rightarrow A) laser with output up to 5.8 J/pulse has been demonstrated. The photolytic pumping scheme begins withe-beam excitation of xenon to produce Xe*2fluorescence at 172 nm. This VUV radiation is transmitted through an array of CaF2windows into the laser cell, where it photodissociates XeF2to produce primarily XeF(Bfrac{1}{2}). Collisions with N2buffer gas relax the excited states to XeF(Cfrac{3}{2}), which lases on a transition centered at 481 nm and continuously tunable over more than ±35 nm. Typical values of the experimental parameters were as follows. The 420 kV, 1 me-beam source delivered an average current of 10 A/cm²over an aperture 14 × 100 cm for pulse lengths up to 1 μs. Totale-beam energy available was 3.5 kJ, of which 2.4 kJ was deposited in the xenon. The total VUV energy radiated was 720 J, of which 115 J was coupled into the laser cell. This produced 32 J of available XeF* energy, of which up to 18 percent was extracted as laser energy. The total system efficiency was 0.2 percent. Optimized designs should achieve better than 1 percent efficiency.     

Effect of nitrogen on XeF(C→A) and Xe2Cl laser performance

Experiments demonstrating the effect of nitrogen on electron-beam pumped XeF(C rightarrow A) and Xe2Cl laser performance are reported. The laser power of the XeF(C rightarrow A) laser decreased with increasing nitrogen pressure, whereas the Xe2Cl laser power increased by a factor of three at an optimum nitrogen pressure of 200 torr. Atomic absorptions in both laser spectra are decreased by the addition of nitrogen. The kinetic mechanisms leading to the observed behavior are discussed.     

Single-frequency operation of a long-pulse e-beam excited XeF(C-A)laser

A 1-m gain length e-beam excited XeF(C-A) excimer laser operating in a unique reimaging ring amplifier configuration has been used to amplify an ultranarrowband single-mode dye laser pulse. Double heterodyne detection was used to simultaneously determine the single-mode injection dye laser and the amplified XeF(C-A) laser bandwidths. Fast Fourier transform (FFT) analysis of the pulses indicates that the amplifier output has the same bandwidth as the injected dye laser pulse. The bandwidth of the XeF(C-A) laser was line narrowed by 6 orders of magnitude, from a free running value of 16 nm (20000 GHz) to 20 MHz. Specific output energies of 0.7 J/l at 488 nm and 1.3 J/l at 476.5 nm were measured. Laser output pulse lengths up to 500 ns were observed     

电子束泵浦XeF(C→A)激光的实验研究

给出了电子束泵浦XeF(C→A)准分子激光的实验资料并作了一些初步分析,这些结果是在选用最佳混合气体(对应电子束横向激发采用8大气压Ar,16托Xe,8托NF3;对应纵向激发采用2大气压Ar,8托Xe,3托NF_3)条件下得到的。着重研究了光学谐振腔对宽带内波长调谐性和输出功率的影响。用纵向电子束激发,在74毫微米宽带范围内(从455毫微米到529毫微米)得到了连续可调谐的窄带激光输出。当用棱镜作为色散元件时,其线宽约为5毫微米;如果用衍射光栅代替棱镜则线宽可窄至1毫微米左右。