Dynamic analysis of V-folded cavity for TEM_(00) operation of end-pumped solid-state laser

Based on graphic analysis design method of optical resonator, a simple design expression of V-folded cavity of end-pumped solid-state lasers with TEMoo operation is described, which satisfies two criterias of the resonator design. We give numerical simulation of spot size as a function of thermal focal length using this design approach whose advantages are validated experimentally.     

Theoretical studies on beam parameters of a self－start ring cavity Ti：sapphire laser

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Passive mode locking of a Nd：YAG laser with co－doped Nd, Cr：YAG as saturable absorber

We demonstrate the characteristics of relatively low saturation intensity using co-doped Nd, Cr:YAG as saturable absorber for passively mode locking the Nd:YAG laser. The difference of the saturation intensity between Q-switched and mode-locked operation in co-doped Nd, Cr:YAG was only one to two orders of magnitude, while Cr:YAG was generally reported at a difference of five orders of magnitude. More than 80% mode locking modulation depth was achieved at an incident pump power of 4.4W, corresponding to an intracavity intensity of 6×10^4W/cm^2, using a 68cm long plano-concave cavity.     

Energy reduction:a technique for seed-injection locking of single-axial-mode Q-switched Nd:YAG laser

A new technique for seed-injection locking of single-axial-mode (SAM) Q-switched Nd:YAG laser is re- ported.The technique called energy reduction (ER) is utilized when SAM operation is locked to design its feedback scheme.This method ensures long-term 100% seed-injection locking performance and the pulsed SAM output energy can reach as high as 200 mJ.Both temporal and spatial interferometric experiments have been executed to confirm the SAM oscillation.     

New simplified coupling scheme for the delivery of 20 MW Nd:YAG laser pulses by large core optical fibers

The feasibility of transmitting 20 MW, 5 ns laser pulses from a frequency doubled Nd:YAG laser through a standard 1500 μm multi mode optical fiber is demonstrated. A new coupling scheme employing an optical homogenizer prevents breakdown in air without the use of a vacuum chamber. At the same time a very homogeneous flat top beam profile on the fiber surface is achieved. The new scheme therefore clearly simplifies fiber coupling of high power laser pulses. Experiments on the delivery of more than 20000 pulses with 110 mJ mean energy without fiber damage have been performed. Received: 2 August 2000 / Revised version: 18 August 2000 / Published online: 22 November 2000     

Fabrication of a quartz optical fiber tip for dental treatment with Nd:YAG laser—Proposal of a new process with TiO2 powder

In dental treatment with Nd:YAG laser beam, a quartz optical fiber is generally used to transmit the laser beam, which is irradiated to the hard and soft tissues for a caries treatment and a periodontal tissue excision. Since a normal optical fiber, which the laser beam comes out from the tip of the fiber, has difficulty irradiating to a narrow space and an inner root canal uniformly, it is effective to use a processed optical fiber tip from which is obtained a diffused and circumferential laser beam. In this paper, a new process to obtain these laser beams with TiO₂ powder is proposed, and the characteristics and the performances of the processed optical fiber were investigated. An experimental instrument was developed to measure the energy partition radiated from the processed fiber tip, and the ratio of a straight beam, a sideways beam and heat generated by the absorption of the laser beam was measured in each condition. As a result, the ratio of an energy partition was controllable by changing the incidence parameter to process the fiber tip, and the processed fiber tip corresponding to the clinical purpose could be obtained. The parameters which affected the processability of the fiber tip were processing time and incidence laser energy. The prepared cavity with processed fiber on the enamel was influenced by a straight beam, and the removal of enamel to the depth direction was controllable by using the processed fiber.     

High-sensitivity CW Fabry–Pérot enhanced spectroscopy of CO2 and C2H2 using a 1064-nm Nd:YAG laser

2 (20⁰3←00⁰0) R(6), C₂H₂ (2100⁰1¹←0000⁰0⁰) R(12), and C₂H₂ (1200⁰3¹←0000⁰0⁰) P(6) near 1064 nm using CW cavity ring-down spectroscopy and CW cavity transmission. An effective interaction length of more than 30 km was achieved (cavity finesse ≈86000) and the sensitivity was ≈10^-8 cm^-1. Higher sensitivity of 3.3×10^-11 cm^-1/ was obtained by cavity-enhanced wavelength modulation spectroscopy. The absorption coefficients, pressure broadening coefficients, lineshapes, line strengths, and absolute wavelengths of those lines were determined, some of them for the first time. The measurements were carried out over a wide range of pressures from the strongly inhomogeneous to the strongly homogeneous region. Received: 25 May 1998/Revised version: 28 July 1998     

一种CCD辅助测量基模(TEM_(00))激光光斑尺寸的方法

激光光束是一种振幅和等相位面都在变化的高斯球面光波 ,其最小光斑的位置和大小不易确定 ,本文在实践的基础上提出一种测量基模 ( TEM0 0 )激光光斑尺寸的方法 ,解决了这一问题     

小功率可调式TEM_00模CO_2激光器

本文给出获得TEM00模输出的小功率CO2 激光器制作工艺     

基模动态稳定望远镜谐振腔

本文使用等价腔和传播矩阵方法,在一般情况下推导出了望远镜腔的基模热稳条件,该表示式简单而又严格,还易于推广到含热透镜多元件腔的一般情况,并与用近似方法所得结果作了比较和讨论。     

角锥棱镜激光谐振腔的基本特性

分析了角锥棱镜对光束的相位变换作用,带二面角误差的角锥棱镜可等效于6块光楔的组合,其楔角的大小和方向由二面角误差决定。对在腔内往返传输的光线在镜面上的位置进行了分析,结果表明：3个二面角误差相同且不为零的角锥棱镜构成的谐振腔为约束非稳腔。用Fox-Li迭代法数值模拟得到了不同棱镜二面角误差情况下的谐振模式。模拟结果表明：圆形镜腔情况下基本振荡模式接近于TEM03模的拉盖尔高斯光束;当3个二面角误差不相同时,模式中各个区域的强度分布不对称。采用3个二面角误差基本接近且绝对值较小的棱镜可以提高光束质量。     

交叉棱镜腔Nd:YAG板条激光器

对稳定和非稳共焦型Nd:YAG板条激光器的特性作了理论分析和实验研究.证实了使用交叉棱镜腔的流动空气-水混合冷却板条激光器有高的光束质量和对棱镜失调的不灵敏性,可望获得某些实际应用.关键词:交叉棱镜腔,板条激光器.     

Experimental studies of an unstable confocal resonator alexandrite laser

The effects of excited converging wave in an unstable confocal resonator onthe properties of an alexandrite laser are investigated experimentally.The results show thatexciting the converging wave inside the resonator is an effective method to reduce the diver-gence of the laser beam for low gain laser medium.     

利用特征向量法分析有源失调腔的2维模场

 利用一种用于光腔模式及光束传输模拟计算的特征向量法计算有源腔的2维失调,通过对谐振腔几何关系的求解,以及对增益进行薄层模型处理,最后利用特征向量法计算有源腔失调后的模式分布,发现失调造成了模式强度分布不均匀,并带来模式阶数的改变。计算了相应的光束质量因子,结果表明:在一定失调范围内,失调可能会带入新的模式竞争;谐振腔在一定范围的失调情况下,各阶模式的光束质量可能变好,也有可能变差,随着模式阶数的增加光束质量整体趋势是越来越差;原来简并的模式可能不再简并。该方法可以为计算失调后谐振腔的模场带来方便。     

利用特征向量法分析有源失调腔的2维模场

利用一种用于光腔模式及光束传输模拟计算的特征向量法计算有源腔的2维失调,通过对谐振腔几何关系的求解,以及对增益进行薄层模型处理,最后利用特征向量法计算有源腔失调后的模式分布,发现失调造成了模式强度分布不均匀,并带来模式阶数的改变。计算了相应的光束质量因子,结果表明:在一定失调范围内,失调可能会带入新的模式竞争;谐振腔在一定范围的失调情况下,各阶模式的光束质量可能变好,也有可能变差,随着模式阶数的增加光束质量整体趋势是越来越差;原来简并的模式可能不再简并。该方法可以为计算失调后谐振腔的模场带来方便。     

输出功率5.2 W的全固态连续单横模671 nm红光激光器

设计了全固态连续单横模671 nm红光激光器.利用880 nm LD双端端面泵浦Nd:YVO4复合晶体,实现了均匀泵浦并改善了激光晶体热效应;考虑到影响倍频转化效率的各种因素,优化设计了Z字形四镜激光谐振腔,采用I类临界相位匹配晶体LBO作为腔内倍频晶体;当泵浦功率为42.5W时,获得了5.2W的连续单横模671 nm红光输出,光-光转化效率达到12.2％,激光器长期功率稳定性优于±2.5％(1 h).     

微波同轴腔高阶TM模式参数的计算

用FORTRAN语言编程计算了微波圆柱同轴谐振腔TM工作模式的系列关联参数。给定合适的几何结构参数范围与模式参数范围,就可快速算出同轴腔内所有可能存在的腔体尺寸、本征频率、纵向电场强度极大值的位置对应的半径以及该位置处的特性阻抗。这样,设计者就可以根据特定的需要,从计算出的大量结果中选取符合要求的结构参数,为下一步仿真和实验提供依据,减少了设计初期冗长反复的仿真模拟和试错实验。用3维电磁场软件ISFEL 3D对计算结果进行仿真发现：计算结果与仿真结果有很好的一致性,说明自编程序的计算结果可以作为多注速调管谐振腔设计的优选或优化数据库,可以提高其设计的准确性和效率。