基于微透镜阵的外腔谱组束系统光束质量分析

针对基于微透镜阵的光纤激光外腔谱组束系统的光束质量评价问题,利用高斯光束的传输变换理论,建立了评价谱组束激光光束质量的理论模型.通过数值模拟,详细分析了各相关参数对谱组束光束质量的影响,结果表明:在基于微透镜阵的谱组束系统中,离焦量、微透镜焦距及模场半径是影响谱组束激光光束质量的主要因素;阵列宽度对谱组束激光光束质量影...     

广角透镜光线计算程序设计的几个问题

本文把透镜的成象光束定义为充满光阑口径的物方入射光束,主光线为成象光束中心线,并给出了寻求它们的方法;同时指出了这些定义与传统方法的定义在透镜设计中所出现的差别;最后给出一个计算实例和进行象差自动平衡时能够控制增加轴外视场光能量的一个象差G。     

全息剪切干涉法测量透镜几何象差

本文用全息双频光栅剪切干涉装置对透镜几何象差的测量进行实验研究。将象差光束中两剪切干涉光线的交点看成点源,提出了用经典杨氏干涉观点、由剪切条纹图确定这些交点的空间位置而直接得到几何象差的杨氏条纹分析法。对几个透镜的象差作了测量和分析;与设计理论值作比较,二者符合良好。     

高重复频率LD侧面泵浦Nd∶YAG电光调Q激光器

文中介绍二极管激光侧泵浦 Q开关激光器 ,激光介质是 Nd∶YAG板条 ,几何尺寸为 2 0 .3mm× 5 mm× 2 .5 mm,二极管激光与板条之间用柱透镜耦合 ,激光谐振腔为平凹腔 ,输出镜曲率半径为 1m,透光率 T=0 .33。用 KD★ P电光 Q开关 ,得到输出脉宽为 12 .7ns、单脉冲能量 1.97m J的激光 ,光束质量 M2x=2 .6 9、M2y=1.87,重复频率 98Hz     

基于非球面透镜组激光光束整形设计

本文针对激光显示领域激光光束光强均匀分布要求,本研究基于非球面透镜组激光光束进行整形设计。文中通过阐述激光光束光强均匀分布原理,着重论述了出射光束分布选择、线映射函数及球面参数确定3个非球面透镜组设计内容。在此基础上,选择匀化洛伦兹函数为输出光束的光强分布函数,展开实例设计分析,旨在基于该设计方法将入射光束准直的单模高斯激光光束整形为光强均匀分布的准直平顶激光光束。     

激光光束平行漂移对聚焦光斑位置影响的理论分析

本文引入象差函数分析聚焦激光光学系统焦点附近的光强分布。推导出了激光光束平行漂移对聚焦光斑位置影响的公式。分析表明,平行漂移将使聚焦光斑产生纵向焦移和横向焦移,其大小取决于光束平移量ρ_0,球差系数S_1,出瞳半径a以及高斯参考球的半球R_0。     

球对称折射率二次方分布的平板透镜的三级象差系数

本文解析地找到了球对称折射率二次方分布的平板透镜的傍轴光路,并用 P.J.Sands 提出的不均匀透镜的三级象差理论推导出了三级象差系数。     

利用光纤和调制半导体激光的准直方法

本提出了一种新的激光光纤准直方法。利用光传播的平行性和直线性，光学准直技术被用于精密地建立几何参数的测量基准，在这些应用中，光束、处理电路的漂移、杂散光是影响测量精度的主要因素。为了消除这些影响，本利用调制半导体激光技术和光纤技术形成准直光束，四象限探测器进行探测，相敏检波技术对光电调制信号进行解调，所有的信号共享同一信号处理信道，且光束的调制频率远离杂散光的频率范围，激光光束漂移杂散光、电路漂移被抑制，在１ｍ范围获得了０．３μｍ的准直精度。     

60瓦半导体激光器光纤耦合器件

应用光纤列阵耦合方式，对大功率半导体激光器线列阵输出光束的快轴方向用一根柱透镜准直，准直后的光束耦合到光纤列阵中，实现出纤功率为60瓦的大功率半导体激光二极管线列阵光纤耦合器件，耦合效率大于80％，光纤的数值孔径NA为0．11。     

GaAs激光窗口与透镜材料的制备原理和方法

目前,激光技术已广泛应用于医疗、测量、工业、军事和高科技等领域。在各种类型的激光器中,高功率CO2激光器在我国工业加工中例如:热处理、切割、焊接、表面合金化与涂敷等行业应用得已十分普遍。对于激光器和激光加工机来说,窗口和透镜则是十分关键的部件。从某种意义上讲,没有窗口就不会产生激光,没有透镜就无法进行激光加工。在有限的几种适合制作窗口和透镜的材料中,由于GaAs具有较好的综合性能因而受到人们的重视。本文仅对GaAs激光窗口及透镜材料的制备原理和方法做一简单介绍。     

Total-reflection active-mirror amplifier for high pulse energy and high average power by using a composite ceramic

A total-reflection active-mirror (TRAM) amplifier is functionally designed by using a composite ceramic for high pulse energy and high average power. A chirped-pulse regenerative amplifier with a cryogenic TRAM has been successfully demonstrated as a feasibility study. A 3.5 mJ pulse energy is obtained at a repetition rate of 100 Hz. The corresponding energy fluence on the TRAM is as high as 1.5 J/cm² for 0.46 ns short pulses. The M²-factor is below 1.1 and no significant beam distortion is observed.     

Surface-emitting semiconductor lasers and laser arrays

Various types of surface-emitting semiconductor lasers are reviewed along with their anticipated applications. The recent progress in grating-coupled surface-emitting (GSE) lasers is particularly emphasized. SuchGSE arrays have operated continuously to more than 3 W and pulsed to more than 30 W. They have obtainedCW threshold current densities of under 140 A/cm² withCW differential quantum efficiencies of 20 to 40% per surface. Linewidths in the 40 MHz range have been obtained with output powers of 100 to 250 mW. The arrays typically consist of 10–30 mutually injection-coupled gain sections with 10 laterally coupled ridge-guided lasers in each gain section. A single GaInAs strained-layer quantum well with a graded index separate confinement heterostructure geometry allows junction down mounting with light emission through the transparent GaAs substrate. A surface relief grating is used for feedback and outcoupling.     

半导体微腔激光器瞬态特性的分析

建立了反映半导体微腔激光器特性的模型,借助计算机手段,运用Matlab软件直接给出了半导体微腔激光器瞬态响应的仿真结果及载流子密度和光子密度的相图,分析了自发辐射因子、注入电流和腔长对微腔器的激射阈值、延迟时间、驰豫振荡频率和光输出等参量的影响。该模型及有关结合为半导体微胶激光器的工艺制作,改善的高频调制特性和优化器件提供了理论依据。     

Nd:YVO_4/KTP激光碘分子超精细光谱和稳频研究

用Nd :YVO4/KTP腔内倍频环形激光器产生的 5 32nm波长激光 ,探测到了波长在 5 32 .170nm至 5 32 .2 0 0nm范围的一系列碘的多普勒吸收谱线和饱和吸收谱线。理论计算出相应的波长值和超精细谱线结构参数。理论计算值与实验测量数据在较高的精度内相一致。用三次谐波锁定的稳频电路实现了该激光器在碘饱和吸收线超精细分量上的频率稳定。     

1.55μm InGaAsP-MQW自对准压缩台面高速DFB激光器

采用一种自对准压缩台面结构制作高速1.55μmDFB激光器。激光器的典型阈值为12mA，单面斜率效率达0．157mW/mA，出光功率大于20mW。由于采用窄条p-InP作为电流阻挡层，因此激光器的寄生电容可降至2.5pF,-3dB调制带宽可达9.1GHz。     

Efficient upconversion-pumped continuous wave Er3+:LiLuF4 lasers

We report on detailed spectroscopic investigations and efficient visible upconversion laser operation of Er³⁺:LiLuF₄. This material allows for efficient resonant excited-state-absorption (ESA) pumping at 974 nm. Under spectroscopic conditions without external feedback, ESA at the laser wavelength of 552 nm prevails stimulated emission. Under lasing conditions in a resonant cavity, the high intracavity photon density bleaches the ESA at 552 nm, allowing for efficient cw laser operation.We obtained the highest output power of any room-temperature crystalline upconversion laser. The laser achieves a cw output power of 774 mW at a slope efficiency of 19% with respect to the incident pump power delivered by an optically-pumped semiconductor laser. The absorption efficiency of the pump radiation is estimated to be below 50%.To exploit the high confinement in waveguides for this laser, we employed femtosecond-laser pulses to inscribe a cladding of parallel tracks of modified material into Er³⁺:LiLuF₄ crystals. The core material allows for low-loss waveguiding at pump and laser wavelengths. Under Ti:sapphire pumping at 974 nm, the first crystalline upconversion waveguide laser has been realized. We obtained waveguide-laser operation with up to 10 mW of output power at 553 nm.     

On the multiplicity of Bismuth active centres in germano-aluminosilicate preform

Spatially resolved optical spectroscopy of Bismuth-doped germano-aluminosilicate fibre preform prepared by modified chemical vapor deposition (MCVD) reveals the existence of two subnetworks accommodating the active centres connected to Bismuth doping: a pure silica subnetwork and an aluminosilicate one. Even at low Bismuth doping level for which laser generation in the fibre has been demonstrated, two kinds of optical centres in a silica subnetwork can be identified. At least one of these centres is able to inhibit the laser generation in aluminosilicate fibres at high Bismuth doping levels. We discuss the technological issues for improving the efficiency of Bi-doped fibre lasers in the spectral range of 1150-1500 nm.     

Applications and performance of high power lasers and in the battlefield

This paper reviews the status and applications of a defensive weapon based on high power lasers, in the battlefield. Laser weapon is a novel concept which utilizes high power laser beam to traverse the distance into incoming objects at a speed of light, and then, destroy or disable it. Various types of lasers and configurations will be discussed in this review including gas lasers, solid state lasers, fiber lasers and the free-electron laser. We will discuss various configurations such as airborne laser (ABL), diode pumped crystals and disk lasers as well as heat-capacity lasers. Recent applications of ultrafast solid state lasers for non-lethal or low collateral damage applications will be presented.     

Optical gain calculation of mid-infrared InAsN/GaSb quantum-well laser for tunable absorption spectroscopy applications

We report on optical gain calculations of a dilute-nitride mid-infrared laser structure designed to be grown on InAs substrate. The active region is composed of several strain-compensated type-II “W”-like InAsN/GaSb/InAsN quantum wells adapted to operate near 3.3 μm at room temperature. For typical injected carrier density σ = 1.1012 cm^− 2, the theoretical laser structure performances reveal a gain value at around 1000 cm^− 1 at 300 K, inducing a modal gain value equal to 50 cm^− 1. Low radiative current densities lower than 100 A/cm² are predicted, indicating that this dilute-nitride structure could operate at 300 K with small threshold current density.