Multifunctional high-performance 10-J level laser system

In this letter,we report a multifunctional high-performance Nd:glass laser system.Laser pulses from an all-fiber front end are first amplified by a regenerative amplifier to 10 mJ level,and then further amplified in a four-pass amplifier.The laser system can provide 10.3-J,3-ns laser pulses at 1053-nm wavelength.The shot-to-shot energy stability is better than 1.5%(RMS).The output laser beam is near diffraction limit.Binary amplitude masks are used to maintain a flat top near-field profile with a 71%fill factor.After the frequency conversion process,7 and 5.5 J pulses at 526.5 and 351 nm are obtained,respectively.     

Multifunctional spectrofluorimetric system

A new type of spectrofluorimetric research system is constructed. It is composed of a number of easily interchangeable optical instruments and is characterized by its wide aperture, 1 : 3, versatility and extendability. Some methods of testing the performance and of optimizing the construction are described. The system serves for recording emission and excitation spectra, their anisotropies (in-phase or our-of-phase, at several geometries), as well as the low-temperature absorption spectra. A pressurized sample compartment serves for the O₂-quenching measurements in the kinetics of excited-state processes.     

美国舰载激光系统的成熟度评估

技术成熟度作为一种重要的评估工具,可为武器装备的国防采办提供更为全面的决策依据,并有效降低装备研制中的技术风险.简要介绍了国外技术成熟度评价方法,研究了技术成熟度评估在美国舰载激光系统LaWS中的应用.LaWS系统由发射望远镜、作战光源、测距仪、目标跟踪单元、总控子系统等5个子系统组成,在系统开发中,除了少量的定制部件...     

Multifunctional universal SPM nanoprobe fabrication with laser technology

Scanning probe microscopy (SPM) is a high spatial resolution method of surface topography visualization and measurement of its local properties. The detecting of interaction arising between the sharp solid-state probe and the sample surface is the foundation of SPM. In dependence from nature of this interaction the scanning tunneling microscopy (STM), scanning force microscopy (SFM), scanning near field optical microscopy (SNOM), etc. are distinguished. The spatial resolution of all types of probe microscopy determines both sharpness of increasing of interaction between a probe and a sample at their approach, and shape and size of a top of a solid-state probe. So, the progress in SPM information capabilities is highly depends on probe properties and first of all on properly fabricated aperture size. Fabrication procedures are rather complicated because of nanometric scale size of aperture and hard requirements to reproducibility and need to be improved. The way how to do it by laser-assisted drawing-out is involving of feed-back in a processing procedure-results in two types of feedback for the process of drawing-out has been suggested, tested and installed into the technological set-up. Different probes have been fabricated by above mentioned laser-assisted stretching during this work: SNOM types from optical fibers, micropipettes from quartz glass capillaries, micropipettes with microwires inside and with metallic covers outside. Some examples of application of above mentioned combined probes for cell membrane technology are described. Most important from them are topographical studying of cells and bacteria in living condition (in liquid) and studying of the mechanical properties of cell (rigidity of cell membrane) using the nanopipette as a tip of a force sensor. Except for that using the model sample the measurement of ion current that runs through nanopipette which also carries out a role of a tip of a force sensor have been done. Thus it is shown, that using a probe as a nanopipette, it is possible to combine SPM method with well-known patch-clamp method.     

Spontaneous decay controlled inversionless laser in a V-type four level system

By using a semiclassical approach, we obtain 16 coupled optical Bloch equations involving density matrix elements for a V-type four level system with three closely spaced upper levels irradiated by a single mode of the electromagnetic field. The off-diagonal elements of the density matrix ρ_ij are in general complex and arise due to the interference between the probability amplitudes of the levels i and j. Through the complex off-diagonal density matrix elements, we introduce the phase angles between the levels participating in dipole allowed/forbidden transitions. Therefore, the phase angles may be regarded as the outcome of the quantum coherence. Under rotating wave approximation, we use a perturbative approach to solve these Bloch equations analytically. These solutions for density matrix elements are used to obtain a closed form analytical expression for the imaginary part of the polarization and hence the absorptive lineshape. The proper choice of the decay constants induces the necessary coherence responsible for inversionless laser.     

自制激光水平尺

利用磁铁、铝片和水平激光模组等制作了电磁阻尼摆式激光水平尺,该激光水平尺制作简单、使用方便.     

氙灯泵浦kW级固体热容激光器电源系统

kW级固体热容激光器的电源系统由大功率高压恒流充电单元、储能单元、放电控制单元、脉冲氙灯与预燃单元、总控与测量单元等部分组成.实际应用表明,该系统已达到了单脉冲输出能量7.5 kJ,重复工作频率10 Hz的设计指标,并具有平均功率高、效率高、可靠性好等特点.     

Ultrafast population transfer in a Λ-configuration level system driven by few-cycle laser pulses

The feasibility of population transfer from a populated level via an intermediate state to the target level driven by fewcycle pulses is theoretically discussed.The processes of on-or far-resonance stimulated Raman scattering with sequential or simultaneous ultrashort pulses are investigated respectively.We find that the ultrashort pulses with about two optical cycles can be used to realize the population operation.This suggests that the population transfer can be completed in the femtosecond time scale.At the same time,our simulation shows that the signal of the carrier-envelope-phase-dependent effect can be enlarged due to quantum interference in some conditions.Our theoretic study may promote the research on the coherent control via ultrashort pulses in the related fields.     

Decay rate measurements of upper laser level in He-Cd+ laser

The decay rate of² D _5/2 level of Cd II has been measured by the magnetic-field power-dip method. The decay rate at the zero-pressure limit is found to be 2.4·10⁶s⁻¹. The calculated collision cross section for excited Cd ions with He atoms equals 0.91·10⁻¹⁵ cm². This work was supported by the Institute of Quantum Electronics. WAT Warszawa, within the project 06.2.3.     

全光纤激光器实现kW级功率输出

 搭建了一台全光纤结构的光纤激光器。采用双端泵浦结构,共有36个泵浦输入端。在使用其中的24个泵浦输入端,泵浦功率为1 477 W时,获得了1 008 W高功率输出,光光转换效率为68%。输出激光的中心波长为1 082 nm,半波全宽为3 nm。目前激光器输出功率受限于泵浦功率,增加泵浦源的数目有望进一步提高输出功率。     

全光纤激光器实现kW级功率输出

搭建了一台全光纤结构的光纤激光器。采用双端泵浦结构,共有36个泵浦输入端。在使用其中的24个泵浦输入端,泵浦功率为1 477 W时,获得了1 008 W高功率输出,光光转换效率为68%。输出激光的中心波长为1 082 nm,半波全宽为3 nm。目前激光器输出功率受限于泵浦功率,增加泵浦源的数目有望进一步提高输出功率。     

激光冲击强化激光器的研制

针对近年来发展的激光冲击强化技术,采用1级谐振8级放大的系统结构和模块化设计方法,研制出了激光冲击强化用短脉宽、大能量的Nd:YAG脉冲激光器,并对激光器技术指标进行了测试分析。在预热20 min后、环境温度变化小于2 ℃的情况下,单脉冲最大输出能量高达25 J,能量不稳定度小于3%,脉宽16~20 ns可调,脉宽不稳定度小于1 ns,光束发散角小于等于2.5 mrad,重复频率达5 Hz。对TC4钛合金进行激光冲击强化实验,大幅度提高了TC4钛合金试件表面的残余压应力。结果表明,研制的激光器各项性能良好。     

激光冲击强化激光器的研制

针对近年来发展的激光冲击强化技术,采用1级谐振8级放大的系统结构和模块化设计方法,研制出了激光冲击强化用短脉宽、大能量的Nd:YAG脉冲激光器,并对激光器技术指标进行了测试分析。在预热20 min后、环境温度变化小于2 ℃的情况下,单脉冲最大输出能量高达25 J,能量不稳定度小于3%,脉宽16~20 ns可调,脉宽不稳定度小于1 ns,光束发散角小于等于2.5 mrad,重复频率达5 Hz。对TC4钛合金进行激光冲击强化实验,大幅度提高了TC4钛合金试件表面的残余压应力。结果表明,研制的激光器各项性能良好。     

Energy extraction in dual-wavelength Q-switched laser with a common upper laser level

The effect of lower-laser-level lifetimes on Q-switched pulse generation in a dual-wavelength solid-state laser with a common upper laser level was numerically and experimentally investigated. A rate-equation model that accounts for finite lower-laser-level lifetimes was developed, and for a Nd:YAG laser operating at 1064 and 1319 nm, numerical simulations of dual-wavelength pulse generation were performed with and without the effects of lower-laser-level lifetimes. In the laser experiments, characteristics of the dual-wavelength Q-switched pulses agree reasonably well with theoretical predictions. As a result, we found that both the total energy of the two Q-switched pulses and the ratio of 1064–1319-nm pulse energies were strongly affected by the lower-laser-level lifetimes when the Q-switched pulse width was comparable or shorter than the lower-laser-level lifetime.     

激光系统中半导体激光器温度稳定系统研究与设计

激光器系统中半导体激光器的功率输出稳定度和工作温度有很大的关系,为了使大功率半导体激光器输出功率稳定,需要对激光器实现高精度、快速温度控制。针对现有的激光系统中激光器温度控制系统存在控制精度不够高、控制速度慢等问题,设计了一种温度稳定系统,采用PT-100热电偶测量激光器温度,并使用最小二乘法对温度数据进行拟合,使得温度测量精度达到0.01 ℃;使用改进粒子群算法优化(PSO)的PID控制器实现温度控制。仿真实验和实际测试表明,所设计的温度稳定系统能够很好地控制激光器温度,达到目标温度所需的调节时间小于11 s,达到稳态后温度波动在±0.02 ℃内。与传统的温度控制方式相比,所设计的系统能够实现参数自整定并自动调节温度,对大功率激光系统中激光器温度具有良好稳定效果。     

Pulsed resonant laser interaction in three level systems

We present a simple treatment for three level transitions excited by a doubly resonant laser pulse. Explicit solutions are derived in special cases. For the strong pulse case we show that the wavefunction can be expressed as a precessing vector.     

飞焦级脉冲激光能量测量方法研究

为解决1 fJ～1 pJ脉冲激光能量的测量问题,提出了一种基于时域波形积分的飞焦级脉冲激光能量测量方法。该方法采用光电倍增管（PMT）获得飞焦级脉冲激光的响应信号,该微弱响应信号经放大、校准与激光脉冲时域波形积分后实现飞焦级脉冲激光能量测量。根据该方法设计了飞焦级脉冲激光能量测量装置,并分析了该装置的测量不确定度。实验表明,该装置实现了波长1 064 nm、脉冲宽度5 ns～1 s、能量范围1 fJ～1 pJ的脉冲激光光源的能量测量,测量不确定度为15.8%。     

Trend of laser research developments in global level

An up-to-date progress of the international laser research and development is given in this article. The number of scientific publications and filed patents are considered as a figure of merit and based on these numbers the growth pace and important aspects are investigated. We have used the Science Finder Scholar search engine, which indexes more than 4000 journals, in different languages, and represents most significant published materials in laser science and engineering. The growth of the laser and related fields are described in terms of resulting scientific publications for the period of 1990–2003. The share of top nations in scientific publications, and in particular laser publications in terms of their gross domestic product (GDP) is presented. It is noted that the four countries including the USA, Japan, Germany and China have a laser publication contribution of 58.9% while the rest of the world including 189 countries contribute 41.1%. However, for the case of patent, which is a more important factor, these four countries hold a share of 90.1% while the remaining nations have a small share of 9.9%. The USA heads all the nations in the number of scientific publications, citations, and laser publications, however, in terms of accepted laser patents Japan shows a big lead. Scientific scopes of the laser systems are presented and some requirements to be met in each field are described. The key points in this field of research, which might be helpful in the future development of the laser technology are discussed.