激光自倍频晶体研究和应用进展

激光自倍频晶体是一类同时具有激光和非线性效应的复合功能晶体。以激光自倍频晶体制作的全固态激光器具有体积小,调整方便,稳定性高等优点。自1970年代以来,以LiNbO3,YAl3(BO3)4倍频晶体为基质的激光自倍频晶体实现了自倍频激光运转。近年来,以RECa4O(BO3)3(RECOB)为基质的激光自倍频晶体受到重视和广泛研究。本文从对激光晶体、非线性光学晶体及激光自倍频晶体的基本要求出发,在综述激光自倍频晶体研究历史的基础上,讨论了激光自倍频晶体中的基波和倍频光,探讨了NYAB和Nd:GdCOB一类晶体中晶体长度,Nd3+浓度和效率之间的关系。理论估算表明,当浓度适当,晶体长度10mm时,这两类晶体的光–光转换效率可达30%以上。本文总结了NYAB系列晶体的研究历程及RECOB系列激光自倍频研究的思路及取得的成果。在最近10年中,利用山东大学生长的Yb:YAB晶体,获得1.1 W自倍频绿光,光光转换效率为10%;在RECOB体系中,比较了各种晶体的特点,选定Nd:GdCOB为主要研究对象,经过晶体掺钕浓度和长度关系,位相匹配方向、膜系及热工程等多方面研究,获得了1.36 W的545 nm绿光输出,光–光转换效率为17.1%;输出功率为1.03 W时,半小时功率波动不超过1%。这是目前为止,Nd3+离子激光自倍频晶体的最好结果。文章最后介绍了激光自倍频晶体的可能应用。通过理论和实验分析,认为到目前为止Nd:GdCOB是以Nd3+为激活离子最后的激光自倍频晶体,而在Yb3+为激活离子时,Yb:YAB晶体最佳。     

半导体激光自混频干涉技术对振幅的测量

激光自混频干涉是一种非常特别的现象 ,在许多应用中 ,通常都尽可能地避开来自各种各样的光器件反馈到激光器腔内的光 ,把它看成是有害的 ,例如 :来自光纤端面、或大型光学系统中的各个小光学镜面表面的反射光 ,这些光都能增加噪声及改变半导体激光的一些特性 ,这种性质的惊人影响已由Lenstra[1] 等人详尽描述过。然而 ,激光自混频干涉技术正是应用这种外反馈光携带的可被提取的信息对振动振幅和频率进行测量。     

半导体激光自混频干涉式传感器中的干涉与调制

应用F-P模型，阐述了半导体激光自混频干涉式传感器的干涉与调制过程，同时给出了相应的计算．     

一种新型的半导体激光自混频式麦克风

对激光自混频技术进行了分析，制作了半导体激光自混频式麦克风。     

线性调频半导体激光器自混频干涉理论模型

使用半导体激光器在弱反馈条件下的动力学理论,建立了线性调频半导体激光器的自混频干涉理论模型.基于该模型,分析了激光器振荡频率偏移与输出功率变化特性.通过测量激光器输出功率谱,可以得到激光器前端面与被测目标之间的距离.     

一种新型的激光自混频测振的方法

1引言在激光器的许多应用中，我们都尽可能的避开出射光的自反馈现象．尽管如此，还是被来自各种各样的光学元器件所组成的共振腔产生的反射光所困扰．自反馈不仅增加了噪音强度，而且同时大大改变了激光器输出的特性曲线，这种作用的性质已被Lenstra等人‘’‘描述过．然而我们正是利用了这种“不利”的特性构成了自混频激光测振系统．2基本原理激光自混频干涉的简单装置如图1所示．首先由激光垂直照射在待测物体上，利用从待测物体上反馈的光对激光器输出功率调制，然后从尾光接收调制信号，这种可被提取的携带外界馈信息的光反馈调制后…     

激光自混频干涉法测量表面粗糙度的研究

对半导体激光自混频干涉法测量表面粗糙度中的干涉效应进行了理论分析,推导了干涉信号与表面粗糙度的数学关系式,讨论了影响测量信号的因素及表征表面粗糙度的评定参数,即表面轮廓的方均根偏差。结果表明,随着加工表面粗糙度的降低,反射光的强度逐渐增加,被测物体表面的反射率越高,越有利于测量。     

半导体激光自混频干涉法测振动速度

应用半导体激光自混频干涉方法可研究物体的振动速度．本文阐述了测速的基本原理，给出了信号分析的理论依据和计算方法。     

纳米流体激光自混频功率谱及其计算

激光自混频技术可用于纳米颗粒和纳米流体的探测。在纳米流体自混频信号自相关函数的基础上,理论推导了功率谱函数的表达式。结果表明,纳米流体的激光自混频信号功率谱是洛伦兹线型和高斯线型的卷积,即佛赫特(Voigt)线型。通过数值计算研究了各种典型情况下激光自混频信号功率谱的频谱特征,颗粒定向运动速度决定了多普勒频移和高斯线宽,颗粒粒度决定了洛伦兹线型的宽度,颗粒粒度和速度与功率谱之间的对应关系为纳米流体的测量提供了理论基础。     

激光二极管泵浦NYAB激光器的空间分布速率方程的研究

报道了用以描述激光二极管泵浦ＮＹＡＢ连续激光顺空间分布特性的非线性耦合的速率方程组，和以此方程组进行的理论计算，讨论了泵浦光和激光的空间分布、晶体的最佳长度、输出镜的最佳透过率对激光器输出的影响，给出了ＮＹＡＢ激光器设计的一些依据。     

Theoretical Analysis on the Simultaneous Operation of a Color-Center Laser and a Q-Switched Nd:YAG Laser

The simultaneous operation for the Q- switched Nd: YAG laser at 1.06 and the tunable color-center laser over 1.12～1.26 μm has been realized by using a LiF: F2- color-center crystal both as the Q-switcher for the Nd:YAG laser and as the active medium for the color-center laser. The interaction of the two lasers has been analyzed and calculated with the rate equations. The pulse duration of YAG laser is compressed, in agreement with the experimental results.     

Space phase matching and self-frequency-doubling red laser in Nd:GdCOB crystal

By using the calculation theory of the phase-matching direction and effective nonlinear coefficient of frequency doubling in biaxial crystal, we calculate the effective nonlinear coefficients at different frequency-doubling phase-matching directions of the three main fluorescent lines (936, 1060, 1331 nm) of Nd:GdCOB crystal. The space distribution curves of effective nonlinear coefficient are drawn. Two crystal specimens are cut at the optimal type I phase matching angles: for specimen 1, θ=65°, Φ=34.6° (the first octant); for specimen 2, θ=66.5°, Φ=145.5° (the second octant). When pumped by Datachroom-5000 pulsed dye laser, the output self-frequency-doubling red laser in specimen 2 is 0.62 mJ, and the corresponding conversion efficiency is 2.5%. Under the same pumping condition, the output red laser of specimen 1 is much smaller than that of specimen 2, which is well in agreement with the theoretical calculation.     

LD泵浦Nd：BGO晶体的自调Q激光器

首次实现了ＬＫ泵浦Ｎｄ∶ＢＧＯ固体激光器的１．０６４μｍ的激光输出，泵浦阈值功率为２５ｍＷ，在连续运转状态下得到最大为４０ｍＷ的ＴＥＭ００模输出，光－光效率为１３．３％，根据法拉第磁光效庆理论，了ＬＤ泵浦Ｎｄ∶ＢＧＯ自调Ｑ激光器的各种参数，并研制成该激光器，在该器件中，作为损耗调制元件的磁光调制器就是绕有线圈的Ｎｄ∶ＢＧＯ晶体本身，实验在重复率为１ＫＨｚ的条件下得到了ＦＷＨＭ为１００ｎｓ的稳定脉冲     

Xenon Flash Lamp Pumped Miniature Nd:S-VAP Pulsed Laser

ＸｅｎｏｎＦｌａｓｈＬａｍｐＰｕｍｐｅｄＭｉｎｉａｔｕｒｅＮｄ：Ｓ－ＶＡＰＰｕｌｓｅｄＬａｓｅｒＸｅｎｏｎＦｌａｓｈＬａｍｐＰｕｍｐｅｄＭｉｎｉａｔｕｒｅＮｄ：Ｓ－ＶＡＰＰｕｌｓｅｄＬａｓｅｒ￥ＺＨＡＯＳｈｅｎｇｚｈｉ；ＷＡＮＧＱｉｎｇｐｕ；ＺＨＡＮ...     

Passively Q-switched self-frequency doubling Nd:Ca4GdO(BO3)3 laser with Cr:YAG saturable absorber

Nd³⁺ : Ca₄GdO(BO₃)₃, known as Nd : GdCOB, is a new self-frequency doubling laser crystal. Using Cr⁴⁺ : YAG as passive Q-switch, we have realized the Q-switched laser running at 0.53 μm with an Nd : GdCOB crystal. Meanwhile, the pulse width, the single pulse energy and the repetition rate under different small-signal transmission of Cr⁴⁺ : YAG and different pump conditions are measured and the numerical solutions of the coupling wave rate equations agree with the experimental results.     

Second harmonic generation from precise diamond blade diced ridge waveguides

Carbon ion irradiation and precise diamond blade dicing are applied to fabricate Nd:GdCOB ridge waveguides. The propagation properties of the fabricated Nd:GdCOB waveguides are investigated through experiments and theoretical analysis. Micro-Raman analysis reveals that the Nd:GdCOB crystal lattice expands during the irradiation process. Micro-second harmonic spectroscopic analysis suggests that the original nonlinear properties of the Nd:GdCOB crystal are greatly enhanced within the waveguide volume. Under pulsed 1064 nm laser pumping, second harmonic generation (SHG) at 532 nm has been achieved in the fabricated waveguides. The maximum SHG conversion efficiencies are determined to be ～ 8.32 %·W^-1 and ～ 22.36 %·W^-1 for planar and ridge waveguides, respectively.     

Laser performance of monolithic Cr,Nd:YAG self-Q-switched laser

The self-Q-switched laser performance of monolithic Cr⁴⁺,Nd³⁺:YAG concave-planar resonator with 5-mm length was studied experimentally and theoretically. The slope efficiency is as high as 24% and pump threshold is as low as 64 mW. The pulse width, the single pulse energy and the pulse repetition rate of monolithic Cr,Nd:YAG self-Q-switched laser were measured as a function of absorbed pump power. With the increase of pump power, the pulse width decreases and the pulse energy and the pulse repetition rate increase. The average output power of 91 mW with pulse width of 7 ns at repletion rate of 35.5 kHz was obtained at the maximum absorbed pump power of 440 mW, the peak power is as high as 370 W. The theoretical prediction of pulse energy, pulse width and pulse repetition rate as a function of absorbed pump power based on rate equations is in a good agreement with our experimental data. This can lead to develop the diode laser-pumped monolithic self-Q-switched solid-state microchip lasers.     

Surface second-harmonic generation based on periodically poled LiNbO3 nonlinear optical crystal

We have generated a second-harmonic generation(SHG) of a Q-switched microchip Nd:YAG laser on the surface of a periodically poled LiNbO3(PPLN) nonlinear crystal near the grazing incidence angle.Three individual SHG waves as transmitted homogeneous,inhomogeneous and reflected radiations have been generated and their intensities are measured and characterized within a desirable range of about 10 different incidence angles of the Nd:YAG laser as pump source on the PPLN surface.The basic of surface nonlinear radiation is also investigated and similar results are calculated and extracted from the theory.Comparison between calculated and measured data shows that they are in good agreement with each other.