激光、激光技术 激光器结构与设计

TN2422006054034热透镜谐振腔参数对指向精度的影响=Influence of ther-mal lens resonator on pointing stability[刊,中]/路鑫超(华北光电技术研究所.北京(100015)),刘先达…//激光与红外.—2006,36(6).—448-451从谐振腔理论出发,论证了谐振腔参数与谐振腔灵敏度对热透镜谐振腔指向精度的影响,计算了经过优化后的热透镜谐振腔参数,并通过实验测量了不同谐振腔参数下输出激光的指向精度。实验结果表明,优化后的热透镜谐振腔具有较高的指向精度。图6参6(王淑平)激光、激光技术 激光器结构与设计…     

自缩短效应对Kerr被动锁模激光器稳定区的影响

利用谐振腔的往返矩阵理论以及谐振腔的稳定性条件研究了锁模激光器的稳定区与激光腔内光功率的关系,从而得出在高脉冲功率下自缩短效应对Kerr被动锁模飞秒激光器的稳定区的影响.利用激光谐振腔的此性质可以对Kerr被动锁模激光器的谐振腔的设计进行优化,从而提高其锁模的可实现性以及谐振腔的稳定性.     

多个激活元件激光器振荡模体积的匹配

本文利用矩阵方法研究了由多根YAG:Nd棒串接的高功率连续激光器,这些激光棒的几何尺寸和热聚焦特性可以是不同的。通过电子计算机计算求得了描述激光器运转特性的参量(特别是振荡模体积匹配参量)随激光谐振腔几何结构和激光棒热焦距变化的函数关系。同时,对两根不同的YAG:Nd棒的串接振荡进行了实验研究,获得了与理论分析一致的结果。 关键词：     

关于开式谐振腔振荡模的角分布

激光器件输出的角分布(或“输出的方向性”、或“输出光束的发散角”)是一个十分重要的参量.它关系到激光的某些十分重要的应用.为了达到改善方向性的目的,有必要对目前常用的几种谐振腔的角分布特性作一个大致的了解.为此,对平行平面谐振腔和球面共焦谐振腔的角分布作一个初步的探讨. 一、问题的公式化 为叙述简便,只讨论一个方形(或矩形)反射面的谐振腔经分离变量后的二维问题. 表征谐振腔性质及其规律的,是谐振腔的本征方程[1]:其中X(x、x')是积分核,它基本上决定了谐振腔的性质.对于不同形式的谐振腔它是不同的.谐振腔内存在着很多的振…     

猫眼激光谐振腔横模选择特性研究

将猫眼逆向器作为激光谐振腔的一个腔镜组成猫眼谐振腔。介绍了猫眼逆向器的结构,阐述了猫眼逆向器中凸透镜和凹面镜的间距改变时猫眼曲率半径的相应变化,并通过有效地控制该间距来选择激光横模,从而保证基横模输出。在激光谐振腔衍射积分方程的基础上,运用牛顿柯特斯数学方法,对不同参量下的猫眼激光谐振腔的横模状况进行分析,得出了各阶横模对应的特征值和功率损耗,计算出保证基横模输出的参量,并与实验对比,得到了一致的结论,为激光器的横模选择和控制提供了一种简便易行的新方法。     

降低热不稳定性的激光二极管泵浦固体激光器

通过谐振腔腔结构理论研究了在端面泵浦固体激光器中,等效热反射镜曲率半径变化时,振荡光半径的变化速率理论和实验都表明,通过调整谐振腔的参量,使得该变化速率接近零,可以有效地抑制热效应导致的激光功率不稳定性。     

660nm单一波长Nd∶YAG陶瓷激光器

针对陶瓷晶体1319nm的谱线设计了适合的谐振腔腔镜膜系参量,采用激光二极管列阵侧向抽运掺杂1.1at%、Φ3×50mm的Nd∶YAG陶瓷,利用色散棱镜及KTP晶体Ⅱ类匹配腔内倍频,研制了一台660nm单一波长输出的高重频Nd∶YAG陶瓷红光激光器.根据陶瓷晶体的热透镜焦距设计了谐振腔的各个参量,在重复频率为1000Hz、单脉冲抽运能量约144mJ时,获得了3.9mJ的660nm脉冲激光输出,总的光-光转换效率为2.71%.为进一步研究大功率、高效率的陶瓷红光激光器奠定了基础.     

铅卤钙钛矿法布里-帕罗谐振腔激光器

随着后摩尔时代的到来,对大容量、高速度信息处理的需求使得半导体器件应用由电子集成转向光子集成,高性能微纳激光器是实现光子集成的重要环节.种类丰富的半导体材料促进了半导体微纳激光器的快速发展,近年来,随着大量新型半导体材料(如二维半导体、铅卤钙钛矿等)的涌现,有望实现半导体微纳激光器性能的进一步提升.由于钙钛矿材料具有高光吸收、缺陷高容忍、激子结合能大等优异光学性质,使其成为高增益、低阈值半导体微纳激光器的优秀候选材料.法布里-珀罗(F-P)谐振腔激光器是钙钛矿激光器中研究广泛、结构简单、应用价值较高的一类激光器.本文以铅卤钙钛矿F-P谐振腔激光器为例,对其工作机理以及近年来的研究成果进行综述,从激子与光子弱耦合的光子激光和强耦合的极化子激光两个方面出发,详细介绍了钙钛矿材料既作为增益介质又作为谐振腔的F-P结构激光器以及仅作为增益介质的F-P腔激光器的激光的产生原理和影响因素,最后总结了钙钛矿F-P谐振腔激光器当前面临的挑战,展望了其进一步发展可能具备的前景.     

晶体热效应对LD端面泵浦固体激光器优化设计的影响

考虑了激光介质因受热不均匀而引起的热效应对激光器衍射损耗和谐振腔基模尺寸的影响,利用M²因子来描述泵浦光在激光介质中的传播规律,根据泵浦光在激光介质中的有效泵浦体积最小以提高泵浦效率这一判据,给出了含有泵浦光束质量因子M_p²和激光介质参量在内的端面泵浦固体激光器的优化设计曲线,利用这些曲线可方便地指导完成激光器的最佳化参量选择.利用上述理论,对LD端面泵浦光纤耦合输出的Nd:YVO₄激光器进行了研究,实验结果和理论分析相符合.     

XeF(C-A)蓝绿激光线宽压缩技术

利用表面放电光泵浦XeF(C-A)蓝绿激光器开展了激光线宽压缩技术研究,分别采用谐振腔腔镜谱带重叠法和光栅谐振腔法实现了线宽小于10 nm的窄线宽激光输出。采用谐振腔腔镜谱带重叠法,激光输出线宽约7 nm,采用光栅谐振腔法可以将激光线宽压缩到约1 nm,并实现XeF(C-A)激光的可调谐输出,调谐范围为470~495 nm。     

Research on a middle infrared and long infrared dual-band laser

We propose a continuous-wave(CW)middle infrared(MIR)and long infrared(LIR)dual-band laser for the calibration and effect research of infrared detecting and imaging systems.A total output power of 18 W is achieved by the proposed dual-band laser through one DF gain medium module and one parallel placed CO2 gain medium module using a common stable resonator and output mirror with nominal transmissivities of ～5%in the MIR band and～10%in the LIR band.Spectra of dual-band laser are acquired.The power extracting efficiency of this dual-band laser can be significantly improved,as validated by a single-band test of optimized parameters.     

Design of SMMW Laser Resonators with On-Axis Signal and Pump Beam Guiding in a Mirror Ring

A ring resonator design for optically pumped submillimeter wave (SMMW) lasers using the same set of four mirrors (including one focussing mirror) for pump beam and SMMW beam guiding is introduced.The optimum design is discussed on the example of a 2.523 THz methanol laser. It turns out that the focal length of the focussing mirror has to be adapted to the resonator perimeter. Eleven well suited focal length - resonator perimeter ratios, defining eleven standard resonator configurations, can be distinguished.The setup of an experimental laser with the optimized resonator and the experimental setup to measure laser performance are described, and results concerning laser output power, beam quality and efficiency are discussed.This paper is the extended version of the paper presented on the 23rd International Conference in Colchester [1] and continues a former article presented in this journal [2].     

A model describing the single and multiple line spectra of tunable microcrystal lasers

A theoretical model is derived by which the occurrence of the single and multiple emission line spectra of tunable microcrystal lasers is described. These spectra in general exhibit several emission lines, arising from the Stark-split atomic levels of the lasing ions in the crystal field. The model is based on the shift of the resonator frequencies due to the thermally induced shift of the optical resonator length and demonstrates that the coincidence of the resonator frequencies with the laser gain lines leads to the emission of single or multiple line spectra of microcrystal lasers. These spectra can be described by the model. The model is given as a set of criteria. In this way not only can predictions of the single emission-line tuning range be made but also resonator lengths can be optimized in order to obtain a maximum tuning range. Furthermore, Q-switched operation can be achieved for specific parameters by periodically shifting the resonator frequencies. The linewidth of the gain used in this model depends on the laser threshold and is folded with the thermal shift of the atomic transitions. Therefore the centre wavelength of the gain is assumed to be constant. The advantage is that this experimentally relevant linewidth can be measured easily with microcrystal lasers themselves, whereas spectroscopic data do not take laser threshold behaviour into account. It is shown that the results of the model are in good agreement with experimental data measured for two different Nd: YAG crystals. Simply by inserting other material and laser parameters, the model can easily be applied to other laser crystals and other wavelengths.     

Design of a 2.5 THz submillimeter wave laser with optical pump beam guiding

A ring resonator design using the same set of mirrors for pump beam and submillimeter wave (SMMW) beam guiding is introduced. Optimal design is discussed on the example of a 2.5 THz methanol laser. It turns out that due to refocussing of the pump beam on the pinhole certain focal lengths of the focussing mirror, which mainly is responsible for the beam guiding, should be avoided. Diffraction losses and pinhole losses determine optimalg-parameters for which the pump beam guiding losses of the resonator are minimum, and optimal pump beam waist radii.The setup of an experimental laser with the optimized resonator and the experimental setup to measure laser performance are described, and results concerning laser output power, beam quality and efficiency are discussed.     

Design, simulation and structural optimization of a longitudinal acoustic resonator for trace gas detection using laser photoacoustic spectroscopy (LPAS)

The design of the acoustic resonator is critical for the optimization of the sensitivity of laser photoacoustic spectroscopy (LPAS) in trace gas detection applications. In this paper, an LC circuit model is used for the simulation of a 1D acoustic resonator. This acoustic resonator is designed for CO photoacoustic spectroscopy. The effects of the structural parameters, quality factor and resonant frequency on the performance of the device are theoretically analyzed. The role of the buffer volume as an acoustic filter is investigated and optimized dimensions of the buffer volume, to achieve minimum noise transmission coefficient, are calculated. The effects of the ambient temperature, variety of pressure and gas flow velocity on the resonant frequency of photoacoustic resonator and PA signal are simulated. The temperature dependence of the microphone sensitivity is also introduced.     

LD抽运的折叠腔Nd∶YVO4/KTP倍频红光激光器

对LD端面抽运的Nd∶YVO₄/KTP腔内倍频激光器的三镜折叠腔结构进行优化设计,研究了总腔长、输入镜曲率半径和Nd∶YVO₄和KTP晶体的热效应对激光谐振腔的稳定区域、Nd∶YVO₄晶体内基模光束半径的影响。实验结果表明:该方法所得出的结论与理论相吻合。在实验中比较了折叠腔不同折叠角度的红光输出功率,并获得了最佳折叠角度为25°,其有效倍频效率为10.8%。最后使用基频光的偏振特性与KTP的相位匹配之间的关系对实验结果进行理论解释。     

Optimization of a sealed-off CO2 laser resonator by utilizing a genetic algorithm

A genetic algorithm is used to optimize a CO₂ laser resonator. Three optimal parameters of a CO₂ laser resonator (the diameter of the laser discharge tube, the curvature radius of the concave reflector and the transmissivity of the output-mirror) are obtained with the maximum output of the laser power as the objective function in the genetic algorithm. After the optimization, the calculated laser power with the fundamental mode increases by 62% and the measured value increases by 35% in an experiment as compared to a non-optimized case.     

Induced Raman scattering in the resonator of a primary laser

Raman scattering is examined for substances in the resonator of a primary laser under steady-state conditions in relation to the parameters of the resonator, laser, and substance. Allowance is made for the effects of the Raman scattering on the operation of the primary laser. Relations are obtained for the threshold and optimum (for induced Raman scattering) values of various parameters.     

500.8 nmNd∶YAG青光激光器光学薄膜的设计与制备

从双波长激光运转及和频的机理出发，对LD泵浦Nd∶YAG，LBO腔内和频500.8 nm〖JP2〗青光激光器所使用的光学薄膜进行了设计和制备.在激光反射镜的设计上，为了达到最佳的和频输出，对膜系要求进行了深入分析.采用对谐振腔一端面反射率固定不变并通过对另一腔镜基频光的透射率进行调谐的方法, 在给出合理初始结构后，利用计算机对膜厚进行了优化.并采用双离子束溅射沉积的方法，通过时间监控膜厚法成功制备出青光激光器所使用的全介质激光反射膜, 在室温下实现946 nm和1064 nm双波长连续运转，并通过Ⅰ类临界相位匹配LBO晶体腔内和频在国内首次实现500.8 nm青色激光连续输出.当泵浦注入功率为1.4 W时和频青光最大输出达20 mW.     

Generation of high power and high stability azimuthally polarized beams in a Nd:YAG laser

Generation of high stability and high power azimuthally polarized beams is demonstrated in a Nd:YAG laser by inserting an optimum aperture in the cavity. The location and the size of the aperture are optimized by analyzing the mode-radius, stability and mode selectivity of the cavity with a transfer matrix method. Experiments are performed in a Nd:YAG laser with a flat-flat resonator, and the results are concordant with the theoretical predictions. A 10 W azimuthally polarized beam with the standard deviation of the output power less than 0.6% is obtained.