固体激光器的稳模式势稳条件分析

对传统的稳模式热条件进行了推广，使之也可适用于非球面驻波稳定腔的其它谐振腔，如环形腔等；引入了稳模式弱势稳条件的概念，进而提出了一种折囊的优化市尺－振腔同时满足稳功率热稳条件和稳模式弱热稳条件，从而使和是激光器的输出既稳功率又具有一定的模式热稳定性，如发散角的热稳定性；此外，还给出了球面驻波稳定腔、球面环形稳定腔的稳模式强、弱热稳条件的解析解。     

多板串接板条激光器的理论研究

讨论了多极串接时板条激光器的模体积匹配问题;并用数值计算分析了板条介质在腔内串接时,谐振腔参数的最佳选择.     

四棒串接连续灯泵浦Nd:YAG大功率激光器

 报道了一种符合工业应用的四棒谐振腔连续Nd:YAG激光器。实验中采用对称放置方式四棒串接谐振腔得到2 105 W的平均功率输出，光束参数积24 mm·mrad，系统总光电转换效率达到3.5%。还对影响激光器工作的因素进行了理论分析。     

双棒串接Nd:YAG激光器的稳区分析和实验研究

用传输矩阵法理论分析了在含热致双折射补偿和不含热致双折射补偿两种情况下,r偏振和偏振对双棒串接激光器谐振腔稳区的影响.选用低掺杂浓度的Nd:YAG棒,实验上用含90°石英旋光片的双棒对称平行平面短腔获得了最佳实验结果.1 064 nm激光最高输出功率达482.3 W,对应光-光转换效率为40.2%.     

双棒串接Nd∶YAG激光器的稳区分析和实验研究

用传输矩阵法理论分析了在含热致双折射补偿和不含热致双折射补偿两种情况下,r偏振和Ф偏振对双棒串接激光器谐振腔稳区的影响.选用低掺杂浓度的Nd∶YAG棒,实验上用含90°石英旋光片的双棒对称平行平面短腔获得了最佳实验结果.1064nm激光最高输出功率达482.3W,对应光-光转换效率为40.2%.     

双棒串接Nd∶YAG激光器的稳区分析和实验研究

用传输矩阵法理论分析了在含热致双折射补偿和不含热致双折射补偿两种情况下,r偏振和偏振对双棒串接激光器谐振腔稳区的影响.选用低掺杂浓度的Nd∶YAG棒,实验上用含90°石英旋光片的双棒对称平行平面短腔获得了最佳实验结果.1 064 nm激光最高输出功率达482.3 W,对应光-光转换效率为40.2％.     

高平均功率六棒串接脉冲Nd:YAG激光器

报道了一种腔内六棒串接的脉冲Nd:YAG激光器。采用44矩阵对晶体棒失调角度对谐振腔光轴的影响进行了理论分析,给出了六棒串接脉冲激光器中晶体棒失调角度的允许范围。在串接实验中,谐振腔采用对称平平腔结构,通过调整每根晶体棒的失调角度到允许范围内,实现了六棒串接脉冲Nd:YAG激光器。在输入电功率86 kW,占空比17%时,获得了平均功率3 018 W的脉冲激光输出,峰值功率17.75 kW,最高单脉冲能量为66 J,光束参数乘积为26.3 mmmrad,电光转换效率3.5%,长时间工作不稳定性小于2%。     

高平均功率六棒串接脉冲Nd:YAG激光器

报道了一种腔内六棒串接的脉冲Nd:YAG激光器。采用44矩阵对晶体棒失调角度对谐振腔光轴的影响进行了理论分析,给出了六棒串接脉冲激光器中晶体棒失调角度的允许范围。在串接实验中,谐振腔采用对称平平腔结构,通过调整每根晶体棒的失调角度到允许范围内,实现了六棒串接脉冲Nd:YAG激光器。在输入电功率86 kW,占空比17%时,获得了平均功率3 018 W的脉冲激光输出,峰值功率17.75 kW,最高单脉冲能量为66 J,光束参数乘积为26.3 mmmrad,电光转换效率3.5%,长时间工作不稳定性小于2%。     

双棒串接Nd3+∶YAG激光器

根据测量的单根 Nd3+∶ YAG棒的热焦距 ,利用 ABCD传输矩阵计算了双棒串接的几种腔型的稳定参量 ,给出了能够满足高功率、高稳定性激光输出的稳定腔型 ,实验结果与理论分析基本相符     

激光二极管泵浦固体激光器低敏感度谐振腔研究

提出了对称偏移因子、角扰动失谐率二个参量用来指导谐振腔的设计,使激光二极管泵浦固体激光器谐振腔对机械扰动具有较低的敏感性.在对各个光学元件对称轴偏移量进行定量描述的基础上,提出对称偏移因子.当对称偏移因子很小时,激光器在光学元件的平移扰动下具有较好的稳定性.在对光学元件角度偏转扰动定量描述的基础,提出了角扰动失谐率,当角扰动失谐率较小时,激光器在光学元件角度变化时,具有较好的稳定性.所有的设计方法均应用于凹凹腔进行了分析,并对一些现象进行了实验测量.     

端面抽运固体激光器热透镜效应的实验研究

提出一种易于实现、对激光器本身没有干扰、高空间精度、可实时测量介质热透镜的干涉测量方法. 并利用此方法全面研究了端面抽运Nd:YVO4激光器的热透镜效应，为认识激光介质的热效应和设计此类激光器提供了参考.  关键词： 热透镜 端面抽运 固体激光器     

Control of the pulse duration in one- and two-axis passively Q-switched solid-state lasers

We study theoretically and experimentally different methods to control the pulses emitted by solid-state lasers passively Q-switched by a saturable absorber. We explore one- and two-axis laser schemes allowing to control the pulse duration, which is ruled by the saturation powers of the transitions in the absorber and in the gain medium. In one-axis lasers, it is shown that the adjustment of the pump and laser beam sizes in the active medium and in the absorber provides an efficient means to control the pulse temporal shape and duration. Furthermore, a two-axis laser cavity supporting so-called forked-eigenstate operation permits to freely adjust the parts of the mode power which circulate in the gain medium and in the absorber. In this case, a lengthening of the pulse duration up to 500 ns is obtained with an increase of the average output power. The theoretical results obtained by using rate equations adapted to each cavity geometry are in close agreement with experiments performed on a diode-pumped Nd³⁺:YAG laser Q-switched by a Cr⁴⁺:YAG saturable absorber. The relevance of the different techniques to control the pulse durations in the framework of potential applications is discussed. Received 3 December 2001     

固体激光腔动力学稳定性的调控

在固体激光腔运行中热透镜的屈光度,1ft,作为谐振腔的动力学因子,对腔的运行特性有着关键性的影响作用.运用变换圆图解方法,对固体激光腔的光模特性的动力学稳定性作了详细的分析,给出了它对动力学因子及腔参数u1=L1(L1-R1)R1与u2=L2(L2-R2)R2的依赖关系.给出了腔参数u1与u2的直观物理图像描述;在此基础上,利用变换圆图解方法,进一步讨论,如何选择腔参数u1与u2,调节稳定区内运行的最小基模光斑尺寸和动力学稳定区的宽度,及调控动力学稳定区的‘位置’;提出了两倍拓宽动力学稳定区的一个可行方案;最后,还讨论了动力学敏感腔的存在及其在自调Q激光器与自Kerr透镜锁模激光器中的可能运用. 关键词： 固体激光器 热透镜 动力学稳定性的调控     

Propagation parameters of the beam extracted from a diode pumped Nd:YAG ceramic slab laser with a hybrid stable–unstable resonator

We analyze the propagation properties of the beam extracted from a diode pumped ceramic Nd:YAG slab laser adopting a hybrid stable–unstable resonator. Such a resonator produces a beam characterized by an Hermite–Gauss mixture-like distribution in one transverse direction and a hard-edge diffracted distribution on the other transverse direction. The beam propagation parameters M_x² and M_y² are measured for different values of the diodes driving current. We obtain a beam parameter product smaller than 3 mm mrad in both transverse directions and in the whole range of powers, up to an extraction of 220 W in a QCW regime.     

Out of the blue: semiconductor laser pumped visible rare‐earth doped lasers

The rise of semiconductor‐based pump sources such as In_xGa_1‐xN‐laser diodes or frequency‐doubled optically pumped semiconductor lasers with emission wavelengths in the blue encourages a revisitation of the rare‐earth ions Pr³⁺, Sm³⁺, Tb³⁺, Dy³⁺, Ho³⁺ and Er³⁺ with respect to their properties as active ions in crystalline solid‐state laser materials with direct emission in the visible spectral range. Nowadays, some of these blue‐pumped visible lasers compete with Nd³⁺‐lasers in terms of efficiency and direct lasing at various colors from the cyan‐blue to the deep red can be addressed in very simple and compact laser setups. This paper highlights the spectroscopic properties of suitable rare‐earth ions for visible lasing and reviews the latest progress in the field of blue‐pumped visible rare‐earth doped solid‐state lasers.

     

Optimizing the composite slab sizes in corner-pumped lasers

Using the method of images, a simplified and visualized analytic model to aid in optimizing the geometrical parameters of the corner-pumped composite slab to improve the absorption efficiency is presented. According to the analysis results, the ray trace models are built and simulations are performed. Based on the analytical model and simulation results, the sizes of the composite slabs are optimized to boost the absorption efficiency and pump uniformity. A corner-pumped composite YAG/Yb:YAG slab laser that produced 1016 W continuous wave output power from a single composite crystal, with a slope efficiency and optical-to-optical efficiency of 43% and 34.4%, respectively, was designed. This analysis method may be applied to other obliquely pumped schemes in which the pump direction does not parallel the axis of the resonator.     

The influence of transverse structures on the coupling of solid-state lasers

We demonstrate the influence of transverse structures on the coherent coupling of laser modes. From the Maxwell-Bloch equations in the approximation of a finite mode expansion we derive Adler equations for the relative phases. We use an improved model to describe the gain-induced coupling of two non-orthogonal modes of a solid-state laser. Experimental results for some time-dependent experiments are presented and compared with theoretical predictions of our model.     

大功率固态调制器的仿真研究

设计了大功率固态调制器的新型固态脉冲开关模块。通过分析电力电子仿真软件Saber中绝缘栅双极晶体管(IGBT)物理模型的概念和等效电路,结合实验数据建立了IXDH20N120型IGBT的模型,研究了Saber环境下,不同参数条件和拓扑结构对调制器电路输出特性的影响。仿真结果表明：动态均压网络在有效地保护开关的同时,可以减少IGBT的开关损耗;电路中器件离散性与系统分布参数会造成调制器输出波形质量下降,效率降低。并对调制器在负载打火情况下,因严重不均流而损坏器件故障的机理作了分析,实验证明仿真结果和分析与实际相符。     

太阳光泵浦固体激光阈值的理论分析

为了选择适合太阳光泵浦的激光材料,本文从四能级速率方程出发,综合考虑了太阳辐射带状光谱特性和激光材料对泵浦光吸收能力,建立了太阳光泵浦固体激光理论模型。利用该模型推导得到了单束光侧面泵浦和椭球腔侧面泵浦方式下的泵浦阈值表达式,并结合Nd~3+∶YAG、Nd~3+∶glass、Nd~3+∶Cr~3+∶GSGG(Nd~3+∶Cr~3+∶Gd_3Sc_2Ga_3O_12)、Cr~3+∶BeAl_2O_4和Cr~3+∶Nd~3+∶YAG等激光材料的光谱参数,计算了这些材料的泵浦阈值光强。结果表明:在单束光侧面泵浦和椭球腔侧面泵浦方式下,Nd~3+∶YAG的泵浦阈值光强分别为448个太阳常数和224个太阳常数,是比较适合用太阳光泵浦的激光材料。由于椭球腔的特殊结构,采用椭球腔侧面泵浦激光介质,阈值光强比较低。分析了泵浦阈值光强与材料直径的关系。该模型可用于从现有的激光材料中筛选出在太阳光泵浦下最易输出激光的工作物质。     

Low‐wavelength emission of Nd‐doped lasers

This paper gives an overview of the results obtained with diode‐pumped Neodymium‐doped crystals operating below 900 nm. Operation at such low wavelengths requires considering the strong thermal population of the lower level of the laser transition. Based on a theoretical study and simulations, the paper presents the challenges related to the design of these three‐level lasers. Experimental results are given with Nd:YAG and Nd:vanadate crystals. It is explained how to deal with the line competition with emission at 946 nm or 912 nm. Finally, intracavity second‐harmonic generation is presented. The output powers reach a few hundred mW at wavelengths below 450 nm. Hence, the paper demonstrates the potential of Nd‐doped diode‐pumped solid‐state lasers for applications in the blue range, in replacement of gas lasers such as helium‐cadmium lasers.