直角棱镜平面反射衰减在激光光束诊断中的应用研究

论述了普通光学元件-直角平面反射镜在激光光束诊断中的应用,提出了利用直角棱镜的直角面反射进行光能衰减,详细论述了采用该方法进行光能衰减的可行性,分析了平面反射衰减法在激光束诊断中对测光束的影响,讨论了激光束发散角在直角面反射中的影响,结合半导体光束诊断进行了应用分析.实验证明,该方法结构简单,误差小,调整方便,利用普通反射棱镜直角面衰减即可满足激光强度的匹配要求,实现了待测激光束的无失真取样,达到了很好的测试效果.     

一种大面积高能激光光束参数的在线测量方法

 提出了一种大面积连续波高能激光光束参数的在线测量方法——环形光刀扫描测量法。该方法采用偏心安装的斜面环形光刀高速扫描反射，光电探测器阵列沿反射光圆周均匀布置探测，使得绝大部分被测激光沿原光路传播，只有少量取样光被反射到探测器阵列上。通过对采集得到的探测器响应信号进行空间映射计算和图像复原，得到激光束的光强分布参数。该方法可用于光束直径数百mm的高能激光光束测量，测量空间分辨率约2 mm，时间分辨率为30~50 ms。     

一种新型高能激光束能量分布探测器

 介绍用于探测高能激光束空间能量分布的量热器阵列探测器。这种探测器具有承受激光束能量密度高、探测面积大和能量测试误差小等特点,主要由保护板、量热器阵列的热沉积构成。也给出了探测器的标定和性能测试。该探测器为高能激光束绝对空间能量分布的测量提供了有效的诊断手断。     

自动确定方位的激光束指示器

介绍了一个可以自动确定光束方位的激光束指示器。在立轴支承的转盘中央安装一个平面反射镜,在转盘的圆周边缘处安装一个霍尔传感器。调整半导体激光器,使其激光束的初始方向与立轴同轴,并经反射后水平出射来进行方位指示。利用线性霍尔传感器对地球磁场的敏感性,测出激光束方向与地磁方向的夹角。由单片机控制系统发出指令,由步进电机及精密减速箱驱动立轴转动,通过带动反射镜水平转动来改变激光束的出射方向。指示器工作时,首先应使激光束的方向与地磁方向一致,然后再使激光束转过预定的角度,实现绝对方位角的激光束定向。系统方位角的定位精度可达到0 1′,具有较高的实用价值。     

抛物面反射镜光轴的确定

介绍了一种确定抛物面反射镜光轴的新方法。当抛物面反射镜绕着机械旋转轴旋转时,利用2束平行光(一束与机械旋转轴平行的光和一束与机械旋转轴成一定角度的斜平行光)经抛物面反射镜反射的像点运动,调整抛物面反射镜的位置,使光轴与机械旋转轴重合。理论分析结果表明：其定轴的倾斜误差不大于1′,平移误差不大于5μm。该方法可用于抛物面反射镜检验,也可用于抛物面反射镜的调校工艺中。     

基于激光自混合干涉的物体旋转中心确定方法

在被测物体上设置一低反射率反射镜,激光器输出的激光束入射到反射镜上,激光束经反射镜反射反馈回激光器内.入射光线若偏离被测物体的旋转中心,当被测物体旋转时,将引起激光器的输出功率随角度变化的自混合干涉信号.当入射光线通过被侧物体的旋转中心时,被测物体的角度变化将不会导致回馈光的光程变化,被侧物体旋转时也就观测不到自混合干...     

平面反射镜表面散射光干涉

激光束照射到表面被粘污的反射镜上会产生干涉环,入射光束和反射光束在被粘污表面产生散射光干涉.随着入射角的变化,光束在反射镜玻璃片内光程改变,引起干涉环从中心冒出或缩进,干涉环级数的变化与入射角的平方成正比.     

双波长双脉冲激光三次谐波的产生方法

提出双波长双脉冲激光产生三次谐波的方法。波长不同的两脉冲激光束由反射使它们合拢后通过两块非线性的BBO晶体 ,激光脉冲第一次通过BBO晶体产生两波长的二次谐波 (SHG) ,它们由各自的反射镜反射再次通过BBO又产生了二次谐波 ,这两次产生的二次谐波和基波通过用于产生三次谐波的BBO晶体可产生双波长的三次谐波 ,它们由 45°斜置的耦合镜输出。文中分析了满足二次谐波和三次谐波的四个相位匹配的条件 ,该方法也可用于腔内双波长双脉冲的三次谐波激光的产生 ,给出了相应的实验结果。     

射频激励相移阵列谐振腔波导CO2激光器输出特性研究

为保持器件结构紧凑型的同时获得稳定的高功率、高光束质量激光输出,将相移光学阵列谐振腔技术用于射频激励扩散型冷却板条波导CO₂激光器．实验发现,该设计方案虽然波导结构为矩形宽波导,但是由于采用了具有相移阵列结构的全反射镜,获得的激光束输出空间分布具有阵列输出光束的基本特征．在波导截面为1mm×20mm、增益介质长度为20cm的波导结构条件下,获得了46W的激光功率输出和11.3%的电光转换效率．激光束输出的远场空间分布呈空间压缩的极锐单峰．由于该结构具有的选模特性,远场为单峰空间分布特 关键词：     

激光笔干涉仪的研制

介绍所研制的激光笔干涉仪．由激光笔发出的激光束在反射镜组间不断反射,使光传播距离增大,从而可以清楚地展现具有一定宽度和高度的干涉条纹,故适合于教学以及演讲中对干涉现象的演示和讲解．     

空间层叠矩形阵列式角多路解码光路设计

根据角多路技术原理,提出了一种矩形阵列空间层叠形式的解码光路结构和先分组解码再组内解码的两步解码方式,并针对本实验室的高功率准分子激光系统给出了具体的解码光路设计实例。该方法具有解码精度高,设计误差小,与光路准直、激光参数测量系统等兼容性好,便于加工制作和安装调试等优点。     

矢量光束空间偏振编码的研究

矢量光束独特的空间偏振结构使之应用于空间偏振编码成为可能。提出了一种用一阶矢量光束的偏振分布进行极角空间编码的方法。通过矢量光束生成、光束偏振分布再调制实现了空间编码光束的生成,并采用斯托克斯参数法对空间编码光束进行检测。实验结果证实了一阶矢量光束应用于极角空间偏振编码的可行性,为基于空间偏振编码的激光驾束制导提供了新方法。     

Spectrally Efficient 3D Optical CDMA Using Coherent Spatial Phase–Time Coding/Decoding

We demonstrate a WDM compatible optical CDMA system incorporating 3D spectral phase–time encoding/decoding. We provide coding and decoding using binary [0, π] phase chips for six users at 6 Gb/s, with a single coded signal separated with an acceptable bit-error rate ≤10 ^?9. The coding and decoding method is based on 3D coding of tightly spaced phase-locked laser lines that is compatible with conventional WDM networking. In optical CDMA systems, we propose to provide encoding and decoding done by converting Hadamard codes (used for conventional CDMA system) to the phase codes. We report that duo-binary modulation format is the best with adequate bandwidth compression. We confirm that better simulation results are reached in terms of the Q factor and bit error rate.     

Effect of mutual-injection ways on phase locking of arrays of two mutually injected fiber lasers: theoretical investigation

The effect of mutual-injection ways on phase locking of arrays of two mutually injected fiber lasers is studied theoretically. The phase-locked states of arrays with different ways of mutual injection are given analytically. It is found that different ways of mutual injection will result in different phase-locked states. The relationships between phase locking and ways of mutual injection are also discussed. The results indicate that the unconditionally phase-locked states can only be formed at the reflectors (i.e., fiber Bragg gratings [FBGs] or output faces) linking directly with the couplers. It is also found that only some of these arrays can make two output laser beams phase-locked unconditionally, while the other arrays can only make two output laser beams phase-locked with some conditions satisfied.     

Second-harmonic optimization of computer-generated hologram

A method of optimizing a computer-generated hologram based on parallel second harmonic generation is proposed for holographic femtosecond laser processing. The method, which we call second harmonic optimization, incorporates the width and spatial profile of the pulse into the hologram design. With this method, we demonstrated parallel laser processing with high quality. Because of the enhanced processing accuracy, smaller structures were processed with a smaller energy than in our previous work. In parallel laser processing with 18 beams on a glass surface, the minimum average diameter of the processed structures was 271 nm when the mean fluence of the beams was 0.88 J/cm(2).     

用非共线二次谐波法实现对锁模激光器超短脉冲宽度的测定

用非共线自相关SHG方法测量了Nd:YAG被动锁模激光器的脉冲宽度。非线性晶体ADP的取向是使仅在两束光都存在时才有位相匹配的SHG。两束寻常光之间的夹角在晶体中是20°50′。SHG出现在它们的角分线方向上;倍频输出是非寻常光。所测得的自相关函数的宽度对应着Nd:YAG被动锁模激光器的脉冲宽度为24ps。 关键词：     

Quantum cryptography with direct coding of the bi-photon light

A set of protocols for direct coding/decoding of the bi-photon light is proposed. Security of the protocols is provided by the possibility of obtaining information on the presence/absence of unauthorized intervention in the process of information transfer from the results of measurements for the channel states. Coding is realized by introducing an additional unbalance of the phases of two bi-photon light beams, and decoding is realized by heterodyne detection of quadratures of the bi-photon light followed by calculation of correlations of the quadratures.     

2600W偏振耦合高效率半导体激光光源

将两个中心波长为808 nm,输出功率为1500W的半导体激光叠阵,经过快慢轴准直后,利用半波片将其中一个叠阵的偏振方向旋转90°,使用偏振分光平板的耦合功能,将两个偏振方向相互垂直的激光耦合到一个光路.扩束后再通过焦距为100 mm的聚焦镜组聚焦,提高激光器的亮度.在工作电流为75 A时,输出功率达到了2600 W,...     

Advanced design of conductive polymeric arrays with controlled electrical resistance using direct laser interference patterning

In this work, we report a simple method for the fabrication of regular conducting polyanliline periodic arrays on large areas of glass or gold substrates using direct laser interference patterning. Additionally, by controlling the laser intensity it is possible to precisely tune the width of the periodic arrays and consequently the electrical resistance of the polyanliline strips. The periodic arrays were characterized using scanning electron microscopy, white light interferometry and cyclic voltametry. The great importance of the method reported lies both in its versatility and the ability to control the properties of the modified polymer electrodes with high precision. This is important for prospective applications such as electrochemical sensors. PACS 79.20.Ds; 42.25.Hz; 73.61.Ph; 81.65.Cf     

Beam alignments based on the spectrum decomposition of orbital angular momentums for acoustic-vortex communications

Given the enhanced channel capacity of wave chirality, acoustic communications based on the orbital angular momentum (OAM) of acoustic-vortex (AV) beams are of significant interest for underwater data transmissions. However, the stringent beam alignment is required for the coaxial arrangement of transceiver arrays to ensure the accuracy and reliability of OAM decoding. To avoid the required multiple measurements of the traditional orthogonality based algorithm, the beam alignment algorithm based on the OAM spectrum decomposition is proposed for AV communications by using simplified ring-arrays. Numerical studies of the single-OAM and OAM-multiplexed AV beams show that the error of the OAM spectrum increases with the translation distance and the deflection angle of the transceiver arrays. To achieve an ideal arrangement, two methods of the single-array translation alignment and the dual-array deflection alignment are developed based on the least standard deviation of the OAM spectrum (SD-OAM). By decreasing the SD-OAM towards zero using transceiver arrays of 16 transmitters and 16 receivers, accurate beam alignments are accomplished by multiple adjustments in three dimensions. The proposed method is also demonstrated by experimental measurements of the OAM dispersion and the SD-OAM for misaligned beams. The results demonstrate the feasibility of the rapid beam alignment based on the OAM spectrum decomposition by using simplified transceiver ring-arrays, and suggest more application potentials for acoustic communications.