熔石英介质中强紫外激光自聚焦效应研究

 针对脉冲宽度约1 ns、波长为351 nm的三倍频紫外激光,定量分析了熔石英介质中的自聚焦长度、峰值光强与强紫外激光光束质量及环境条件等因素的关系,研究了产生紫外光非线性自聚焦效应的阈值条件。研究结果表明：在强紫外激光光束质量一定的前提下,可将B积分值定义为自聚焦的阈值条件;入射强紫外激光光束质量越差,在熔石英介质中产生自聚焦的阈值条件越低;即使对于空间分布均匀的理想光束,当空气中存在灰尘时,经过一段距离的传输后,在熔石英介质中将导致强紫外激光自聚焦效应的产生,且灰尘尺寸较大时的自聚焦效应较明显,自聚焦的阈值条件也相对较低。     

线聚焦——实现实用X射线激光饱和输出的关键技术

自从X射线激光问世以来,在产生机制从准稳态到瞬态,抽运方式从横向抽运到纵向抽运,再到全新的掠入射抽运方式的过程中,大增益的饱和输出一直是研究的根本目标.线聚焦问题是实现辐照均匀化进而达到饱和输出的关键.伴随着抽运方式的发展,先后出现了一系列对应的线聚焦器件,取得了不错的线聚焦效果.文章对X射线激光发展历史上出现的主要线聚焦器件进行了总结.     

激光二极管反馈干涉的实验观测

利用LabView软件虚拟示波器和信号源,观测了激光二极管反馈干涉实验现象．实验证明反馈回激光二极管的光的入射方向和入射光强以及信号处理电路的带宽,对反馈干涉信号有很大的影响．     

动态激光衍射法测量细丝直径

基于夫琅禾费衍射理论和巴比涅互补原理,提出了利用激光衍射对细丝直径进行动态测量的方法.该方法具有测量精度高、速度快、非接触、使用方便且易于微机联接实现自动化测量等优点.     

激光驻波场中钠原子沉积图样的理论研究

原子在近共振激光驻波场中受光的作用力汇聚沉积，形成以激光半波长为周期的光栅结构. 利用半经典模型对钠原子束在不饱和驻波场中的运动行为进行了理论研究，用数值方法模拟出在考虑横向温度、纵向速度和自由飞程后钠原子沉积的光栅结构，通过半高宽、对比度对最终沉积图样进行表征，分析了这些因素对沉积的影响，为正在开展的原子光刻实验提供了必要的理论依据. 关键词： 原子沉积 半经典模型 激光驻波场     

Line Narrowing of a Tunable High Pressure CO2 Laser by Means of an Improved Non-Littrow Cavity

A model is reported to foresee ,for different mirror choices, the spectral properties of a high pressure, frequency tunable, CO₂ laser, operating with a non-Littrow grating mounting. The calculations show a larger frequency selectivity for not collimated plane cavities. The model is experimentally verified in a suitable high pressure laser. In particular narrowed linewidths less than 300MHz ( FWHM) are obtained.     

Near- and mid-infrared laser-optical sensors for gas analysis

Semiconductor diode lasers were first developed in the mid-1960s and found immediate application as much needed tunable sources for high-resolution laser spectroscopy commonly referred to as tunable diode laser absorption spectroscopy (TDLAS). In this paper, currently available semiconductor lasers for spectroscopy in the near- and mid-infrared spectral region based upon gallium arsenide, indium phosphite, antimonides and lead-salt containing compounds will be reviewed together with the main features of TDLAS. Room-temperature measurements of atmospheric carbon dioxide near 2 μm will be discussed and recent results obtained with a fast chemical sensor for methane flux measurements based on lead-salt diode lasers operating near 7.8 μm will be presented.     

An airborne diode laser spectrometer for the simultaneous measurement of H2O and HNO3 content of stratospheric cirrus clouds

We describe a tunable diode laser spectrometer for the in situ simultaneous detection of the nitric acid and the water vapour by means of high resolution absorption spectroscopy on rovibronic lines, using a single laser emitting in the mid-infrared (5.8 μm) and a multipass cell. The instrument was designed to be installed on a high altitude aircraft, as a part of a composite payload for atmospheric aerosol studies. The instrument design criteria are discussed and the expected performances are compared with results of laboratory and field operation. Due to the high chemical activity of HNO₃, that makes difficult to use a reference cell, a fast sweep detection of direct absorption was used for the measurement. An absorption sensitivity of about 2×10⁻⁴ was achieved with an integration time of 2.5 s, corresponding to a concentration of about 4 ppb of HNO₃ in the cell and 0.1 ppb in the external aerosol. The data acquisition and processing techniques, based on the full molecular lineshape fitting are also shown and discussed, including some examples of the data acquired during the scientific flights.     

Cr,Nd:YAG self-Q-switched laser with high efficiency output

The high efficient laser performance of self-Q-switched laser in the co-doped Cr⁴⁺,Nd³⁺:YAG microchip with 1.8 mm thickness was demonstrated. The slope efficiency is varied with the reflectivity of output coupler at 1064 nm, and the highest slope efficiency of 26% was obtained for 95% reflectivity of output coupler at 1064 nm. The pulse width, the single pulse energy and the pulse repetition rate for different reflectivity of the output couplers were measured, and the experimental results agree with the numerical calculations of the passively Q-switched rate equations. This can lead to develop the diode laser pumped monolithic self-Q-switched solid-state microchip lasers, especially for the intracavity frequency-doubled solid-state microchip lasers.     

Diode-pumped 671 nm laser frequency doubled by CPM LBO

A design of diode-pumped high-efficiency Nd:YVO₄/LBO red laser is reported. Using critical phase-matching (CPM) LBO, 671 nm red laser was obtained from 1342 nm light by intracavity frequency doubling. With an incident pump laser of 800 mW, using type-I and type-II CPM LBO, 97 and 52 mWTEM₀₀ mode red laser outputs were obtained, with optical-to-optical conversion efficiencies of up to 12.1% and 6.5%, respectively.