二极管端面抽运的固体激光放大器自身热透镜焦距测量

通过分析激光经过热透镜后光束半径的变化，提出了利用放大器测量热透镜焦距的方法.根据激光束传输与变换理论，得到了热透镜焦距的表达式，并分析了其前提条件和近似偏差.最后，基于上述理论分析，测量了激光二极管端面抽运Tm,Ho∶GdVO₄放大器的热透镜焦距. 关键词： 热透镜焦距 固体激光 激光束传输与变换     

Resonator insensitive investigation to thermal lens for end-pumped lasers

Optical pumping of solid-state lasers induces a thermal lens effect in the laser crystal; this thermal effect determines the beam properties. In this paper, the focal length of the thermal lens is calculated, and resonator parameter (g_1 g_2) is obtained, which is insensitive to thermal distortions when the product of the resonator parameters (g_1, g_2) equals 1/2. By using our calculated results, we get the fundamental transverse mode laser output with optic－optic conversion of 48.6%, and slope efficiency of 56.3%.     

Thermal lens determination of LD end-pumped solid-state laser with stable resonator by slit scanning method

A simple method to determine the thermal focal length of LD end-pumped solid-state laser with stable resonator is presented. The M² factor describing the quality of the beam can be obtained by scanning a slit through the multi-mode Gaussian beam field. The waist width of the beam and the corresponding TEM₀₀ under the same parameters of laser are then deduced through the law of multi-mode Gaussian beam propagation. Based on the standard matrix theory of stable resonator, the thermal focal length of the gain medium can be easily achieved. To show the application of this approach, the thermal focal length of an LD pumped Nd:YVO₄ laser is measured and the experimental results are in agreement with the theoretical prediction.     

A simple method to determine the thermal focal length of solid-state lasers with rate equation

A simple method to measure the thermal focal length of solid-state laser with rate equation was presented. By measuring the output beam power of lasers, the beam waist of oscillating wave can be deduced from rate equation under the stable oscillation condition. Based on the ABCD matrix theory, the thermal focus of the gain medium was easily obtained. The thermal focus of a LD end-pumped Nd:GdVO₄ laser was measured and the experimental results agreed with the theoretical predication.     

采用曲率传感器测量热透镜焦距

 分析了用光栅型波前曲率传感器测量热透镜焦距的基本原理,针对高功率固体激光器的工作特点,结合实验现象推导了在热透镜效应较强时热透镜焦距变化的计算公式。对半导体二极管(LD)侧面泵浦的百W级Nd:YAG激光棒在泵浦电流为15~25 A时的热透镜焦距值进行了测量,讨论了可能存在的误差。实验现象和理论分析一致,测量的热透镜焦距值与理论值符合得较好。     

Thermal lens measurement technique in end-pumped solid state lasers: Application to diode-pumped microchip lasers

A simple derivation, which relates the thermal lens focal length in solid state lasers to pump power and a method for direct estimation of thermal lens focal length, is reported. This method is applicable to any type of stable resonator. The method is used for the measurement of the thermal lens focal length with an accuracy of 8% in an axially pumped microchip laser. The variation of focal length with pump power is also measured.     

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     

自加热式铜蒸气激光器的热气体透镜研究

本文分析了自加热式铜蒸气激光器放电管内的热气体透镜效应,并指出不同的铜蒸气激光器在稳定工作时可能等效为正透镜,也可能等效为负透镜。在实验部分,本文给出了热气体透镜焦距与输入功率、缓冲气体压强的关系,描绘了热气体透镜从负透镜变化到正透镜的动态过程。     

一种新的长焦距透镜的制造方法

针对小口径长焦距透镜传统火漆上盘法容易引起零件中心偏的问题，介绍了一种用平行平板上盘来加工长焦距透镜的方法。在加工透镜第二面的时候，取一平行度非常好的平板，将零件反扣在平行平板上，使零件和平行平板保持线接触，然后将透镜灌胶固定。采用这种方法加工（焦距ｆ′＝－６ｍ，口径Ｄ＝７．７５ｍｍ）的透镜，其中心偏角平均为１′，而采用传统火漆上盘法加工同样的透镜，其中心偏角平均为５′     

采用曲率传感器测量热透镜焦距

分析了用光栅型波前曲率传感器测量热透镜焦距的基本原理,针对高功率固体激光器的工作特点,结合实验现象推导了在热透镜效应较强时热透镜焦距变化的计算公式。对半导体二极管(LD)侧面泵浦的百W级Nd:YAG激光棒在泵浦电流为15~25 A时的热透镜焦距值进行了测量,讨论了可能存在的误差。实验现象和理论分析一致,测量的热透镜焦距值与理论值符合得较好。     

利用准直管法测凹透镜的焦距

介绍了利用准直管精确测量凹透镜焦距的方法，该方法借助一个焦距较长的凸透镜与被测凹透镜组成无焦系统，可以使准直管出射光束的张角发生改变；用一辅助凸透镜与一测微目镜进行平行光束的会聚，测出准直管玻罗板线对在辅助凸透镜焦平面上所成像的大小；经过相应计算可得到被测凹透镜的焦距。     

丰富测透镜焦距实验的内容

在普通物理光学实验中，焦距的测量通常使用单透镜作为待测透镜，但单透镜存在各种像差，会使测量结果的物理意义变得不清，对此本提出了一些改进意见。     

1.6 W of TEM00 cw output at 1.06 μm from Nd:CNGG laser end-pumped by a fiber-coupled diode laser array

In this paper we demonstrated and analyzed a high-power cw Nd:CNGG laser end-pumped by a fiber-coupled diode laser array in a convex–concave-type cavity. TEM₀₀ mode output power of 1.63 W was obtained with 27% optical-to-optical conversion efficiency and slope efficiency of 44.5%. Thermal lensing and its variation with the incident pump power for this crystal have been measured. The coefficient for pump power induced diffraction losses of Nd:CNGG crystal have also been estimated for this laser configuration.     

Anomalous variation of thermal lens signal with concentration from rhodamine B in methanol solution

Thermal lens signals in solutions of rhodamine B laser dye in methanol are measured using the dual beam pump-probe technique. The nature of variations of signal strength with concentration is found to be different for 514 and 488 nm Ar⁺ laser excitations. However, both the pump wavelengths produce an oscillatory type variation of thermal lens signal amplitude with the concentration of the dye solution. Probable reasons for this peculiar behaviour (which is absent in the case of fluorescent intensity) are mentioned.     

一种测量二极管侧面抽运固体激光器热焦距的方法

提出了一种能够简单、准确测量二极管侧面抽运固体激光器热透镜焦距的方法,明确提出采用非对称平平腔测量时,激光晶体端面与腔镜的间距不需要为零,并从实验上证明了方法的可靠性. 应用该方法的测量结果可以优化复合折叠和频黄光激光器的结构,保证两束基频在腔内达到最佳的空间重合,提高腔内和频效率. 关键词： 全固态激光器 Nd∶YAG激光器 热焦距 腔内和频     

Review of the formula of thermal focal length in side-pumped laser rods

The expressions of focal length in side-pumped rod lasers are studied. Good agreement is obtained between simulation and experiments reported previously, using Koechner's theory. The results reveal that underestimation of thermal lens accrues from overestimating the material's thermal conduction and without considering the nonuniform heat deposit. In the case of Nd:YAG rods, temperature-dependent variation of the refractive index constitutes the major contribution of thermal lensing, whereas the temperature- and stress-dependent variations of the refractive index make the major contributions of thermal lensing for Nd:Glass rod lasers.     

激光热透镜焦距测量实验及其公式改进

通过平平非稳腔法对激光热透镜焦距进行了实验测量,研究了不同抽运光束腰位置对热透镜焦距的影响.从理论上引入抽运光远场发散角和束腰位置,对端面抽运激光晶体热透镜焦距公式进行了改进.     

从复透过率函数导出薄透镜的焦距

从透射平板的复透过率函数表达式人手,得出薄平凸透镜的焦距,等效地可得到其他薄透镜的焦距,避免了几何光学中对薄透镜焦距的繁琐推导。     

低功率激光热透镜效应的模拟及研究

与高功率激光相比,低功率激光更安全,其热透镜效应对激光功率变化更敏感,更适合用于实验教学.本文利用有限元法模拟低功率激光的热透镜效应,模拟介质温度场和等效热透镜焦距,定量探究低功率激光热透镜焦距与激光功率以及介质热吸收率、厚度的关系.模拟结果与实验数据符合良好,为探究低功率激光热透镜效应实验提供理论依据.     

大孔径长焦距摄远物镜光学系统设计

对于长焦距摄远光学系统,大相对孔径意味着成像亮度更加优秀,但是也伴随着孔径边缘像差变差而难以校正的难题。利用折反系统减小光学系统总长,采用反射结构为基础,搭配前后两组校正镜构成光学系统,设计出大相对孔径,总长较短的摄远光学系统。光学系统工作波段为可见光波段,焦距1 000 mm,F数2.1,摄远比0.52,光学总长远小于焦距,遮拦比45%,全视场MTF在空间频率80 lp/mm处大于0.3,像面直径11 mm。该光学系统镜片全部采用球面镜,光学系统由2片反射镜和7片透射镜组成,结构紧凑,成像质量好。对摄远物镜进行公差分析,得出该设计公差较宽松。