利用四臂腔产生单纵模TEA CO2激光的研究

提出一种新的TEA CO2激光器选单纵模的方法一四臂腔选单纵模.在理论上研究了这种新腔型的反射率的选频特性并预测了其选单纵模的能力.实验中,用此腔型得到了能最达225mJ稳定的单纵模TEA CO2激光输出,且单纵模再现率超过90%.     

脉冲单纵模激光器中标准具精度与选模性能

根据脉冲单纵模激光器中的关键器件F-P标准具的选模原理,定量分析了不同参数F-P标准具的加工厚度精度、角度放置精度以及腔长变化对激光器纵模选择性能产生的影响,得到了对不同参数标准具的光学厚度偏差进行补偿所需的角度偏移量,研究了入射角度对标准具中心波长偏移的影响。这些结果对于脉冲单纵模激光器的机械结构设计、器件加工允差与装配调节精度的设计具有重要意义。在线型腔F-P标准具选模激光器中,得到了最大单脉冲能量8.41 J,脉冲宽度32 ns,近衍射极限的单纵模激光脉冲输出。     

双纵模He-Ne激光器的拍频稳定度分析

对He-Ne双纵模激光器中两纵模的拍频稳定度进行了讨论.理论上分析了影响双纵模激光拍频稳定度的因素,推导出在考虑了频率牵引效应后双纵模的拍频稳定度和单模频率稳定度之间的关系.计算结果表明对于632.8 nm波长的He-Ne激光器,当频率牵引参量σ1为10-3时,双纵模的拍频稳定度约为其中任一单纵模频率稳定度的1000倍.实验证明当单纵模频率稳定度为1×10-9时,其拍频稳定度为3.3X10-6.     

扭转模结构双腔双频Nd∶YAG激光器

为了产生频差可调谐1 064nm双频激光输出,设计了一种扭转模结构双腔双频Nd∶YAG激光器,其两个驻波谐振腔共用相同的Nd∶YAG增益介质,以扭转模结构消弱增益空间烧孔效应,使Nd∶YAG激光器的两个驻波腔均以单纵模振荡,从而获得正交线偏振1 064nm双频激光输出.理论分析了扭转模结构激光单纵模选择原理和双频激光同时振荡原理,实验研究了双频激光振荡特性和频差调谐特性.研究结果表明:双频Nd∶YAG激光器的两个谐振腔能够同时以线偏振单纵模稳定振荡输出,其频差大小可随激光腔长的改变而调谐,频差调谐范围可达1个纵模间隔,实验观察到的频差调谐范围为0.3GHz~3GHz.     

多纵模短腔染料激光放大前后光谱的比较

实验观测了短腔染料激光器输出的多纵模激光及其经一级染料放大的激光光谱，比较了光谱特性。在一定情况下，短腔染料激光器的多纵模激光经放大器放大可产生一个至几个新纵模，新纵模与短腔染料激光器输出的纵模有相似的频率间隔、线宽及频率牵引等特征。新纵模产生属于三阶四光子混频（即四波混频）为主导的非线性光学效应。存在频率牵引表明，增益介质中的多波混频存在频率失配，在这一四波混频中光子能量并不守恒     

多纵模短腔染普激光放大前后光谱的比较

实验观测了短腔染普激光器输出的多纵模激光及其经一级染料放大的激光光谱，比较了光谱特性。在一定情况下，短腔染料激光器的多纵模激光经放大器放大可产生一个至几个新纵模，新纵模与短腔染料激光器输出的纵模有相似的频率间隔、线宽及频率牵引等特征。新纵模产生属于三阶四光子混频（即四波混频）为主导的非线性光学效应。存在频率牵引表明，增益介质中的多波混频存在频率失配，在这一四波混凝中光子能量并不守恒。     

抽运调制条件下超窄线宽掺铒光纤环形激光器的跳模特性研究

搭建了基于光纤迈克耳孙干涉仪的跳模检测系统,对抽运调制条件下的超窄线宽掺铒光纤环形激光器的跳模特性进行了实验研究,测量了由抽运电流标定的表征跳模规律的跳模数据图。结果表明,随着抽运电流的不断增加,激光器先后经历模式稳定区、模式非稳区以及多纵模区三种状态;存在第二抽运阈值,当抽运强度超过这一阈值时激光器由单纵模跳变为非稳定的多纵模。掺铒光纤环形激光器的谐振腔因抽运热效应或外界扰动而变化时,会引发频率漂移与连续跳模现象。     

基于光纤Bragg光栅F-P滤波器及复合双环腔滤波器的单纵模掺铥光纤激光器

提出了一种基于光纤Bragg光栅Fabry-Pérot (F-P)窄带滤波器和复合双环腔滤波器的单纵模掺铥光纤激光器。通过对复合双环腔进行数值仿真并实验制作,结合光纤Bragg光栅F-P滤波器的窄带滤波特性,实现了光纤激光器的单纵模选取。激光器输出波长为1 941.56 nm,光信噪比为55.8 dB,70 min内的波长和功率波动分别小于0.019 nm和1.464 dB。由自制的基于非平衡迈克尔逊干涉仪线宽测试系统测量了所提出的掺铥光纤激光器输出单纵模激光的频率噪声特性,并用β线方法由频率噪声谱估计了不同测量时间下的激光线宽,2 ms测量时间下的典型激光线宽值为14.194 kHz。     

掺铒光纤环形激光器中饱和吸收光栅瞬态特性引发跳模的实验研究

在掺铒光纤环形激光器中插入饱和吸收光栅是获得稳定单纵模激光的常用方法,但跳模难以完全避免.通过干涉仪动态相移解调法将光频跳变实时转化为相位变化,发现了一种由饱和吸收动态光栅的瞬态响应特性导致的跳模新机理.实验测量了由腔长快调触发的规则跳模,获得了跳模规律及成因.此种跳模发生在调制曲线斜率最大值附近区域,通常在相邻模式之间出现,跳模前移频量约为纵模间隔.在同等调制振幅下,抽运功率越高,触发跳模所需的光频调制频率越大,所需的最小移频量也越大.实验结果给出了振动和调制条件下激光器稳定工作的条件,这为设计激光器的隔振封装和确定频率调制工作模式下的调制范围提供了实验依据.     

正反馈选模和调Q技术

把一个由GaAs光电导开关和激光腔中的普克尔盒组成的正反馈回路,用于YAG激光器中,选单纵模和调Q,获得了稳定可靠的单纵模调Q脉冲.     

多模Ar^＋激光时间相干性与输出功率的关系

本文就多纵模Ar~+激光时间相干性(即相干长度)与输出功率的关系进行了实验观测,得到了相干长度与输出功率关系近似为双曲线函数的实验结果,并根据简单的Smith模型,对多纵模激光的时间相干性与输出功率进行了理论分析与数值计算.研究结果表明,理论与实验结果基本吻合.     

直接探测激光测风雷达发射激光线宽对探测的影响

 论述了Rayleigh散射双边缘直接探测激光测风雷达发射激光线宽对探测灵敏度和误差的影响。使用Monte-Carlo方法模拟了大气后向散射回波半高宽(FWHM)和发射激光线宽的定量数值关系。把这个关系拟合为一个二次多项式,计算了由发射线宽引起的测量灵敏度和误差。对于探测波长是355 nm的情况,当发射线宽从单频增加到2 GHz时,后向散射回波线宽从3.853 GHz非线性地增加到5.371 GHz。发射激光线宽的加宽对探测影响很大,当发射线宽从单频增加到2 GHz时,测量灵敏度从0.003 1降低到0.001 9,测量误差从0.323 m/s增大到0.518 m/s,计算中假定探测信噪比和累计激光脉冲数都是1 000。     

一种LD泵浦双向输出固体环形激光器

提出了一种用于激光陀螺仪的LD泵浦Nd∶YVO4双向输出固体环形激光器。计算了谐振腔的环绕矩阵,分析了曲面镜焦距和放置距离对谐振腔稳定性的影响。得出了构成环形腔的稳定条件,光腰最大化条件,以及光束特性。并对所设计的环形腔进行了实验,获得了双向、多纵模基横模连续输出。     

Mobile Rayleigh Doppler wind lidar based on double-edge technique

<正>We describe a mobile molecular Doppler wind lidar(DWL) based on double-edge technique for wind measurement of altitudes ranging from 10 to 40 km.A triple Fabry-Perot etalon is employed as a frequency discriminator to determine the Doppler shift proportional to the wind velocity.The lidar operates at 355 nm with a 45-cm-aperture telescope and a matching azimuth-over-elevation scanner that provides full hemispherical pointing.To guarantee wind accuracy,a single servo loop is used to monitor the outgoing laser frequency to remove inaccuracies due to the frequency drift of the laser or the etalon.The standard deviation of the outgoing laser frequency drift is 6.18 MHz and the corresponding velocity error is 1.11 m/s.The wind profiles measured by the DWL are in good agreement with the results of the wind profile radar(WPR).Evaluation is achieved by comparing at altitudes from 2 to 8 km.The relative error of horizontal wind speed is from 0.8 to 1.8 m/s in the compared ranges.The wind accuracy is less than 6 m/s at 40 km and 3 m/s at 10 km.     

瑞利多普勒测风激光雷达的频率标定方法

频率标定是瑞利测风激光雷达的关键技术。瑞利测风激光雷达中,通过改变压电陶瓷管的电压实现连续调谐F-P标准具腔长,使出射激光频率处于双边缘透过率曲线的交点处。在连续调谐时,由于压电陶瓷管的磁滞效应引起腔长调谐非线性,从而导致系统误差。分析了该误差的原因及特性,提出了静态软件补偿和动态调频跟踪相结合的频率标定方法。若激光出射频率相对F-P标准具漂移小于100 MHz时,在数据反演时补偿该频率偏差;若相对频率漂移大于100 MHz时,将F-P标准具先退回预设腔长以下,通过逐步增加电压的方式,重新实现频率锁定,保证锁定过程处在磁滞回线的电压上升段,避免了磁滞效应引起的误差。多普勒激光雷达与无线电探空仪的两组对比实验中,在15~30km高度,风速最大偏差6.22m/s,平均偏差1.12m/s。     

Accurate Stabilization of a 3 mW Single-Mode Output He-Ne Laser by Intermittent Frequency Offset Locking to an Iodine Stabilized He-Ne Laser

A high-power, unmodulated frequency standard laser light with low running cost is a powerful tool for industrial measurement involving laser calibration and interferometry in length and shape. To obtain such a laser light, we developed an intermittent frequency offset locked laser (IFOL laser). This laser system, composed of an iodine stabilized He-Ne laser (I₂SL) and a high-powered symmetric three-mode He-Ne laser (HP-3ML, optical output=5 mW), provides two stabilization operational modes: (1) independent mode (I-mode) and (2) slave mode (S-mode). Utilizing the frequency pulling effect, HP-3ML is stabilized at the condition of symmetric three-mode oscillation, and a 3 mW single-mode light with frequency instability of 10^-12 is obtained (I-mode). When the optical frequency deviates from the allowed limit during I-mode, HP-3ML is temporarily offset-locked to I₂SL (S-mode) with frequency resettability of 10^-10 and frequency instability of 10^-12. After completion of the drift reset in S-mode, HP-3ML is stabilized in I-mode again, and then I₂SL is turned off. In a typical case of allowed drift in ±1 MHz, repetitive operation of I-mode for 10 days and S-mode for 5 min was satisfactory. Such an intermittent operation reduces the working time of I₂SL dramatically, resulting in low running cost that enables long-term use in industrial measurement.     

Experimental characterization of DFB and FP chaotic lasers with strong incoherent optical feedback

We have experimentally investigated chaotic power oscillations in single-longitudinal mode DFB and multi-longitudinal mode FP lasers as a function of incoherent optical feedback strengths of up to 42%. We have demonstrated the existence of chaos in the output oscillations of both laser types using classical experimental tools such as RF spectrum, standard deviation, and maximum Lyapunov exponent, which all increase with increasing of feedback strength for both in single-longitudinal mode DFB lasers and multi-longitudinal mode FP lasers. It is also shown that power switching among longitudinal modes of multimode FP semiconductor laser is a considerable portion of the chaotic power oscillations for both strong and weak incoherent optical feedback.     

Numerical investigation of multi-beam laser heterodyne measurement with ultra-precision for linear expansion coefficient of metal based on oscillating mirror modulation

This paper proposes a novel method of multi-beam laser heterodyne measurement for metal linear expansion coefficient. Based on the Doppler effect and heterodyne technology, the information is loaded of length variation to the frequency difference of the multi-beam laser heterodyne signal by the frequency modulation of the oscillating mirror, this method can obtain many values of length variation caused by temperature variation after the multi-beam laser heterodyne signal demodulation simultaneously. Processing these values by weighted-average, it can obtain length variation accurately, and eventually obtain the value of linear expansion coefficient of metal by the calculation. This novel method is used to simulate measurement for linear expansion coefficient of metal rod under different temperatures by MATLAB, the obtained result shows that the relative measurement error of this method is just 0.4%.     

Single mode operation of a narrow bandwidth dye laser using a single prism, grazing incidence grating long cavity

The single mode pulsed dye laser is an attractive tool for many spectroscopic applications. Long cavity tunable dye lasers generally operate in multi-longitudinal modes within the bandwidth of gain profile. Single longitudinal mode oscillation can be obtained by either making the cavity short enough or introducing an additional loss mechanism, in which all modes but one have a gain less than their loss. A new technique to achieve single mode operation in a long cavity dye laser, based on Rhodamine 6G dye in ethanol and ethylene glycol solution, pumped by a high repetition rate copper vapor laser, is reported. This laser, which operates in three modes in grazing incidence grating configuration (cavity length of 16 cm), has been made to lase in single mode by increasing the loss in the resonator through beam walk-off.     

紫外域多纵模高光谱分辨率激光雷达探测气溶胶的技术实现和系统仿真

多纵模高光谱分辨率激光雷达是一种新型的高光谱分辨率激光雷达.本文在研究典型高功率Nd:YAG脉冲激光器的多纵模模式及其在大气中传输的气溶胶米散射和瑞利散射光谱的基础上,设计紫外域多纵模高光谱分辨率激光雷达系统,采用窄带干涉滤光片滤除太阳背景光的影响,设计可调谐马赫-曾德尔干涉仪,分离提取多纵模激光回波中的气溶胶米散射和瑞利散射光谱,并利用马赫-曾德尔干涉仪双通道输出的互补性原理,精确反演气溶胶光学参量.系统仿真结果表明,所设计的紫外域多纵模高光谱分辨率激光雷达能够实现10 km高度内的气溶胶光学参量精细探测.