双折射双频激光器输出光偏振特性的实验研究

报道了双折射双频激光器输出光偏振特性的实验研究，实验发现双折射双频激光器两端输出的线偏振光的偏振方向并不一致，而相互有一定的旋转角度，实验也再次证明了激光器输出的是正交线偏振光，而不是晶体本征模的椭圆化了的偏振光。     

角抽运Yb:YAG激光器

报道了一种高功率准三能级激光器角抽运方法，抽运光从板条激光器结构中的板条工作介质的角注入，综合考虑抽运吸收、抽运亮度、晶体的掺杂浓度以及晶体尺寸等因素，进行了角抽运复合Yb:YAG激光器设计，实验上获得了最大连续输出功率400W, 斜效率28%的输出，实验结果充分证明了角抽运原理的正确性和应用于高功率激光器方面的可行性. 关键词： Yb:YAG 角抽运 复合晶体     

电光调制对外部光反馈垂直腔表面发射激光器输出矢量混沌偏振的操控

基于周期性极化铌酸锂晶体的线性电光效应耦合波理论,数值研究了电光调制对外部光反馈垂直腔表面发射激光器(VCSEL)输出矢量混沌偏振模的操控.研究结果表明,VCSEL输出的偏振度随着电光晶体的长度或施加于电光晶体的外电场强度成周期性转换,控制一定的施加外电场强度和晶体的长度,激光器的不同参数下引起初始混沌偏振态都可以转换为其他任意混沌偏振态.特别是合理选择一定的施加外电场强度或晶体长度,VCSEL输出的任意混沌偏振模可以转换为完全一致的两线性混沌偏振模(x和ŷ偏振),即两线性混沌偏振模的能量能够达到稳定和完全均衡.     

410一2200nm角度调谐BBO参量振荡器

介绍了以Nd:YAG激光器的三倍频光作泵浦源，BBO作非线性光学晶体，在410一2200nm波段可连续调谐的光参量振荡器（OPO）的工作原理和实验装置，测定了其调谐曲线的输出能量，并对实验结果做了分析。     

用电光采样法测量相对论电子束团长度

介绍了电光采样法测量电子束束团长度的实验原理和装置,理论分析并模拟计算了被测电子束团库仑场分布、ZnTe晶体的电光效应与束团电场的关系,并利用琼斯矩阵法分析了探测光通过电光晶体时在束团电场作用下的偏振变化、测量信号与束团长度的关系等。分析表明:测量中应使束团库仑场垂直于ZnTe的［001］方向,探测光偏振方向与ZnTe晶体y″轴成45°或者135°夹角,1/4波片快轴与探测光偏振方向夹角应取45°,这时平衡探测器输出信号与束团库仑场Eb成正比。1/4波片的作用是将电光晶体的工作点从非线性段移到线性段,平衡探测的作用是简化信号与Eb的关系,并提高信噪比。为实际测量应用提供参考。     

用电光采样法测量相对论电子束团长度

 介绍了电光采样法测量电子束束团长度的实验原理和装置,理论分析并模拟计算了被测电子束团库仑场分布、ZnTe晶体的电光效应与束团电场的关系,并利用琼斯矩阵法分析了探测光通过电光晶体时在束团电场作用下的偏振变化、测量信号与束团长度的关系等。分析表明：测量中应使束团库仑场垂直于ZnTe的［001］方向,探测光偏振方向与ZnTe晶体y″轴成45°或者135°夹角,1/4波片快轴与探测光偏振方向夹角应取45°,这时平衡探测器输出信号与束团库仑场Eb成正比。1/4波片的作用是将电光晶体的工作点从非线性段移到线性段,平衡探测的作用是简化信号与Eb的关系,并提高信噪比。为实际测量应用提供参考。     

LD侧面抽运Nd∶YAP腔内三倍频蓝光激光器

研制了一台LD侧面抽运Nd∶YAP腔内三倍频447.1nm脉冲蓝光激光器.采用列阵高频激光二极管侧面抽运Nd∶YAP晶体,使用V型折叠腔,LN晶体电光调Q,输出高峰值功率的1341.4nm偏振基频光.选取KTP晶体Ⅱ类临界相位匹配倍频,获得670.7nm红光.使用LBO晶体Ⅰ类临界相位匹配把670.7nm的倍频光与1341.4nm的基频光进行和频,获得三倍频447.1nm的蓝光输出.实验结果表明:优化后的V型折叠腔,可提高非线性转换效率,在平均抽运功率92.4W时,获得了平均功率887mW、峰值功率17.7kW、脉宽50ns的偏振蓝光输出,光-光转换效率为0.96%.     

LD侧面抽运Nd:YAP腔内三倍频蓝光激光器

研制了一台LD侧面抽运Nd:YAP腔内三倍频447.1 nm脉冲蓝光激光器.采用列阵高频激光二极管侧面抽运Nd:YAP晶体,使用V型折叠腔,LN晶体电光调Q,输出高峰值功率的1 341.4 nm偏振基频光.选取KTP晶体Ⅱ类临界相位匹配倍频,获得670.7 nm红光.使用LBO晶体Ⅰ类临界相位匹配把670.7 nm的倍频光与1 341.4 nm的基频光进行和频,获得三倍频447.1 nm的蓝光输出.实验结果表明：优化后的V型折叠腔,可提高非线性转换效率,在平均抽运功率92.4 W时,获得了平均功率887 mW、峰值功率17.7 kW、脉宽50 ns的偏振蓝光输出,光-光转换效率为0.96%.     

高峰值266nm紫外激光器

报道了一种激光二极管(LD)端面泵浦的Nd:YAG声光Q开关高峰值功率266nm紫外激光器。该激光器采用紧凑的平平腔结构,LBO和BBO分别作为其二倍频和四倍频晶体。分别利用高偏振比LD阵列(40∶1)、低偏振比LD阵列(5∶1)及低偏振LD阵列腔内放置布氏片结构进行了实验。当注入功率为25W、调制频率为10kHz时,以上结构分别得到功率0.85,0.61和0.72W的266nm紫外光输出。其中,采用高偏振比LD阵列的输出功率最高,单脉冲能量为85μJ,脉宽为5ns,峰值功率高达17kW,泵浦光到紫外光的光-光转换率达3.4%。     

掺铒光纤激光器自脉冲行为的研究

对掺饵光激光器的自脉冲行为进行了研究。采用半导体激光器连续光泵浦，在较低的泵浦功率下，在掺饵光纤激光器中得到了稳定的１倍周期和２倍周期自脉冲输出，观察到周期性的不等幅脉冲序列输出，在理论上动用光子寿命可变的正交偏振激光场耦合模型对实验进行了分析。结果表明，掺饵光纤激光器中两正交偏振模光子寿命的调节对获得稳定的自脉冲有着十分重要的作用。     

光扇效应对Ce∶KNSBN记录偏振组态的影响

在非同时读出条件下,采用Ar+ 514.5 nm单色激光为光源。以信号光为非寻常偏振光(e光),通过改变抽运光的偏振态,研究不同写入光偏振组态下Ce∶KNSBN晶体的两波耦合特性。结果表明     

偏振态对激光相干合成的影响

为了研究光束相干合成中偏振态的特性,取理想矩形光束进行模拟分析。通过改变偏振态的退偏率、偏振态夹角、参与合成的子束数目等,观察光场在远场叠加的合成效果。讨论了这些因素对远场合成效果的光强分布、峰值功率密度、光束质量因子等的影响。模拟结果显示:当退偏率小于10%、偏振态夹角小于18时,合成后光束质量因子小于1.1。     

大功率高光斑均匀性半导体激光复合光源

 为了获得具有更高输出功率和良好光斑分布均匀性的半导体激光光源,根据半导体激光优良的偏振特性,利用偏振分光棱镜将2束大功率激光束合成为一束更大功率的光束,通过一个发射系统投射。在光束合成前采用非球面光学系统对每个激光器慢轴方向的光束进行扩束,使其与快轴方向光束发散角基本一致。实验证明,此种半导体激光复合光源具有良好的光斑均匀性,其输出功率是2个半导体激光器输出功率之和,完全满足激光制导等军用系统对激光功率和光斑均匀性的要求。     

斜程湍流大气中部分相干艾里光束的偏振特性研究

偏振是激光通信中保密编码的重要参数,研究斜程湍流大气中的偏振特性对激光通信具有重要意义。利用广义惠更斯-菲涅尔原理和偏振-相干统一理论,推导了无衍射的部分相干艾里高斯光束在斜程湍流大气传输中的偏振度解析式,详细研究了湍流参数、相干长度、天顶角、截断因子和分布因子对偏振度的影响。研究结果表明:与水平湍流相比,光束在斜程湍流下恢复到初始偏振需要更长的传输距离。天顶角、接收高度、截断因子、分布因子越大和相干长度越小,光束偏振度峰值也越大。高相干性的高斯光束比艾里光束更易于保持偏振度不变。无衍射艾里光束中选取合适的光学参数更有利于信息传输与编码,本文结果对激光大气通信领域有着潜在的应用价值。     

The correlation between frequency difference and mode polarization in an intracavity birefringent dual-frequency laser

We discuss the correlations between the measured lasing-mode frequency difference and the mode polarization angle in an intracavity birefringent dual-frequency laser. The frequency difference and polarization are adjusted by rotating an intracavity quartz crystal through a large angular range. We propose two kinds of frequency difference: the equal-order frequency difference and the adjacent frequency difference. By measuring the equal-order frequency difference versus the quartz crystal rotation angle, the real physical process behind frequency splitting is revealed. Based on this, the adjacent frequency difference curve is also obtained. The emitted laser beam polarization angle is also measured for large rotations of the intracavity quartz crystal. These measurements reveal the complete process of optical activity in frequency splitting and allow us to predict the trends of frequency difference and polarization angle for large quartz crystal rotation angles. We analyze the correlations between the equal-order frequency difference and the polarization angle based on the experimental results, which show that the certain points on the two curves are inter-related. The principal results agree well with the optical theory of crystals.     

Improved measurements of thermally induced birefringence effects in a laser material using a half-wave plate

The polarization dependence of a probe beam for use in measuring thermally induced birefringence effects in a laser-diode end-pumped Nd:YAG ceramic laser has been investigated. The variation in intensity of the probe beam was found to be 10.2% for a linearly polarized probe beam, 20.6% for a circularly polarized probe beam, and 31.4% for a circularly polarized probe beam using a half-wave plate with a pump power of 12 W. The angle between the analyzer and the inclination of the major axis of the elliptical polarization with respect to the x axis was controlled using a half-wave plate. By combining a half-wave plate with a circularly polarized probe beam, the variation in intensity increased compared with conventional methods.     

An angle-resolved laser incident beam detector based on a pair ofFabry-Perot etalons

An angle-resolved laser detector based on a pair of a non-mechanical scanning Fabry-Perot cavities is described. The differential signal from the two cavities is approximately independent from the polarization of the incident laser beam and it is used to determine the angle of incidence of the beam on the Fabry-Perot cavities. The F-P etalon is made of interferometric filter combination. A laser incident angle sensor experimental platform is built up, and the experiment is carried out with a given laser range finder. When the incident angle is less than 5°, the transmission difference measured by the laser angle sensor is significantly lower than theoretical value, and deviation is more than 10%. When the incident angle is greater than 10°, the deviation is much lower than that of the situation of the incident angle is lower than 10°.     

Rotation of laser beam polarization in acousto-optic devices

When a linear, polarized laser beam is passed through an acousto-optic device, the polarization direction of the outgoing beam is often different from that of the entering beam, and thus a rotation of the polarization angle takes place. This paper shows how the polarization rotation and the intensity can be calculated for different polarization angles. Experimental results obtained with a single crystal germanium frequency shifter in the 10.6 μm region agreed well with theory.     

Optical activity of a cadmium diphosphide crystal

We have experimentally studied the characteristic features of a laser beam, polarized at angles of ± 45° to the horizontal (vertical), passing through plates of varying thickness cut from a CdP₂ crystal and placed between crossed polarizers, as a function of their angle of rotation relative to the vertical axis. We show that a periodic variation in the intensity is connected with the variation in polarization of the laser beam. We have established that the laser beam remains linearly polarized not only when it passes through the sample along the optic axis, but also when it travels at up to a 17.5° angle to the optic axis. In this case, the specific rotation of the plane of polarization along the optic axis is 68.2 degrees/mm for a thicker plate and 83.3 degrees/mm for a thin plate. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 5, pp. 690–693, September–October, 2006.