增损比对激光陀螺影响的研究

光强调谐曲线是激光陀螺工作模式选取和稳频的依据,而陀螺的增损比将直接决定光强调谐曲线的形式.为了提高陀螺准确度,本文对双同位素综合展宽情况下二频激光陀螺出光带宽与增损比之间的关系进行了分析计算,结果表明,激光陀螺的出光带宽与增损比之间存在单调递增的变化关系.数值仿真了不同增损比情况下陀螺的光强调谐曲线,结果表明,根据激...     

激光陀螺光强扫模曲线模高的影响因素与改善途径分析

激光陀螺光强扫模曲线是陀螺稳频的依据,也是激光陀螺环形激光器振荡特性的基本表征,同时也是陀螺性能好坏的重要标志之一.通过引入新的参量——模高,描述光强扫模曲线的其他特征.光强扫模曲线模高是在腔长变化一个0.6328μm条件下对应光强的最大变化量,是反映光强扫模曲线尖锐度的特征量,该特征量与陀螺稳频精度、稳频响应时间等物...     

基于Lamb理论的激光陀螺光强调谐线型研究

He-Ne气体环形激光器是激光陀螺的核心器件。为了避免环形激光器内部与转动方向同、反向的运转模对产生模竞争效应,单纵模工作激光陀螺需要调整增益介质内Ne同位素构成,采取双同位素增益介质。为此,采用Lamb理论和等离子体色散函数,研究增益介质Ne同位素频率分裂、同位素配比、充气压力等因素对环形激光器光强调谐曲线线型的影响。实验上搭建了激光陀螺光强调谐曲线检测实验平台,在Ne²⁰和Ne²²充气比例分别为1:1和7:3,充气压力为400 Pa的条件下,检测环形激光器的光强调谐曲线,验证了理论分析的正确性,该研究为激光陀螺在双纵模频率非对称位置处实现稳频奠定了基础。     

激光陀螺抖动偏频优化研究

基于频率调制理论,分析、仿真计算了正弦抖动偏频和优化后的正弦抖动偏频条件下,激光陀螺输入-输出曲线的特点.结果表明：正弦抖动偏频时激光陀螺的输入-输出曲线在抖动频率的倍频点处存在着动态锁区,其宽度与激光陀螺静态锁区、抖动角振幅有关.采用优化后的正弦抖动偏频可以很好地克服动态锁区,大大提高激光陀螺输入-输出曲线的线性度.试验对比了正弦抖动偏频和优化后的正弦抖动偏频条件下激光陀螺的输出性能.试验结果表明：采用优化后的正弦抖动偏频显著提高了陀螺准确度.     

零闭锁激光陀螺磁不敏感点与放电电流关系的实验研究

零闭锁激光陀螺(ZLG)增益曲线不对称导致左、右旋陀螺的比例因子修正系数不相等,使得当陀螺稳频工作点与磁不敏感点存在频率差时,陀螺零偏对外界磁场变化敏感,降低了陀螺的精度并限制了使用环境。利用兰姆半经典理论分析计算了比例因子修正系数与增损比的关系,并得到了陀螺的磁不敏感点与放电电流的关系,从信号处理系统中排除放电电流变化对控制信号的影响,并进行了实验验证。理论计算和实验结果均表明,线性地改变陀螺放电电流,陀螺磁不敏感点位置会因增益曲线的增损比变化而发生相应线性改变,进而能够通过控制放电电流降低陀螺的磁灵敏度。     

激光陀螺中背向散射的研究

为了研究谐振腔形状变化对激光陀螺中背向散射的影响,基于矢量叠加理论,分析了激光陀螺背向散射源及其对总的背向散射的影响.根据背向散射对顺逆时针光的耦合作用,推导出了总的背向散射系数与顺逆时针旋转光光强的关系式.基于这一关系,设计实验,通过施加电压使谐振腔反射镜到不同位置来改变光腔形状变化,同时测量光强交流量的振幅,得到了总的背向散射系数的变化曲线.通过与仿真结果对比,验证了背向散射的矢量叠加理论.     

四频激光陀螺性能与室温的相关性研究

室温条件下温度对四频激光陀螺零漂的影响非常复杂.为尝试定性找出温度影响陀螺零漂的机理,对室温下陀螺零漂、表面温度、两路信号的光强差及光强和、两臂放电电流差以及和频进行实时监控测试,通过分析计算各个参数与温度的相关系数.得出以下结论:四频激光陀螺各个参数与温度的相关系数随陀螺运行时间的长短而不同,并且陀螺各参数与温度相关系数的逐次偏差也较大,陀螺室温下的温度补偿对四频激光陀螺性能的改善十分有限;室温下和频与温度具有较好的线性关系.但线性比例系数是变化的.     

100nm宽光谱可调谐掺饵光纤激光器

采用1480 nm大功率激光二极管双向抽运,新型铋基掺饵光纤做增益介质,基于旋转法布里-珀罗腔的可调谐滤波器和带通滤波器做选频装置的宽光谱环形腔可调谐光纤激光器,可实现100 nm（1523~1623 nm）激光波长程控连续可调谐输出,激光输出功率大于1.58 mW,3 dB带宽小于0.1 nm,波长重复性准确度小于0.01 nm.     

气体压强对塞曼激光陀螺偏频特性的影响研究

就气体压强对激光陀螺偏频特性影响进行了理论与实验研究.理论推导发现,激光陀螺内部的He-Ne气体压强对其偏频量有重要影响.He-Ne气体比率一定时,偏频量与其内部压强成线性关系.在不同气压下对激光陀螺偏频量与压强的关系进行了实验验证,实验结果与典型参量下的理论结果吻合得较好;给出了不同比率下激光陀螺偏频量与其压强的关系曲线.     

参量荧光脉宽的理论与实验研究EI北大核心CSCD

参量荧光是基于光参量啁啾脉冲放大(OPCPA)技术的光参量放大器的本征量子噪声。它不具备与主激光相同的时域啁啾特性,在压缩器中形成不可压缩的脉冲底座,降低了激光脉冲的信噪比。在小信号增益情况下,基于解析公式给出了不同抽运波形、不同增益、不同系统带宽和啁啾率情况下参量荧光脉宽的演化规律。结果表明:单级放大器输出荧光脉宽正比于抽运光脉宽;荧光脉宽随着增益的增大而变小;增益一定的情况下,荧光脉宽随着超高斯波形阶数的增大而变大。对OPCPA系统而言,展宽-压缩系统对荧光存在色散展宽的作用,其最终输出荧光脉宽与系统带宽、啁啾率紧密相关。基于拍瓦OPCPA(PW-OPCPA)实验平台进行了相关的验证实验,实验结果与理论具有良好的一致性。     

Differential variation of laser longitudinal mode spacing induced by small intra-cavity phase anisotropies

Intra-cavity phase anisotropy causes each laser longitudinal mode to split into two orthogonally polarized frequencies. When the frequency difference generated by small anisotropy is about 40 MHz or less, only one frequency of the splitting mode oscillates while the other is always in lock-in state due to strong mode competition. In that case the longitudinal mode spacing deviates from its original value. And the spacing of two adjacent longitudinal modes shows differential variations depending on direction of cavity length tuning and mode polarization. In this paper, the relationship between spacing variation and small intra-cavity anisotropy is demonstrated experimentally and theoretically. The equivalent fast axis of anisotropy is determined additionally by its correlation with laser intensity tuning of the two orthogonally polarized components. The novel measurement method is successfully tested in several applications.     

Frequency tuning peculiarities of enhanced power monomode He−Ne lasers

Experimental results are presented concerning some peculiarities of frequency tuning of single-longitudinal-mode He–Ne lasers at 632.8 nm which single-mode selection is performed by increasing the homogeneous broadening of laser transition. These include the observation of an asymmetry of tuning regions with respect to the output power maximum; a jump of lasing frequency during which output power drops; and a strong dependence of frequency tuning on gas pressure and output power. In the case of a mixture of ²⁰Ne and ²²Ne isotopes, analytical expressions for the dependence on frequency of output power, unsaturated gain and saturated gain are obtained and computed at different neon isotope concentrations, gas pressures and cavity losses. Simultaneous consideration of these dependences is proposed and used for an explanation of experimentally observed peculiarities in frequency tuning. The obtained results could be used for realization of a frequency-stabilized He–Ne laser of a few milliwatts power for the purposes of multidimensional interferometric measurements.     

A tunable waveguide CO2 laser using Fabry-Perot modulator and fox-smith type mode selector

A tunable waveguide CO₂ laser was constructed and tested. Efficient output was obtained over expanded tuning range making use of the coupling modulation through the F-P modulator. A fox-smith type mode selector was used to obtain the tuning range wider than the longitudinal mode spacing.A continuous tuning range of 2.2GHz was experimentally obtained.     

半外腔Nd:YAG和Nd:YVO4微片固体激光器的腔调谐特性研究

微片固体激光器具有体积小、寿命长等优点,是精密测量仪器的重要光源。构建了平-平、半外腔的Nd:YAG和Nd:YVO₄微片激光器,通过控制压电陶瓷伸缩改变激光器的谐振腔长,同时使用F-P扫描干涉仪和波长计观察纵模和波长。研究了这2种微片固体激光器的腔调谐特性,包括腔长与光功率的关系,激光纵模扫过出光带宽过程的光功率和单、双纵模变化的规律。实验结果表明：腔调谐过程中单、双纵模交替出现,腔长和泵浦电流共同影响激光器的输出模式和光功率。     

650 GHz正弦波导返波管的模拟计算

提出了一种利用正弦波导慢波结构设计的太赫兹频段大功率返波管的新方案。3维粒子模拟研究结果显示:在20 kV的工作电压和5 mA的驱动电流下,该返波管在645.9 GHz频率处将具有1.55 W的峰值功率输出,互作用效率为1.55%,频谱纯净,输出模式为TE10模。通过在15～25 kV之间进行电压调谐,可获得80 GHz的调谐带宽,且峰值输出功率都在1 W以上。     

Fine frequency tuning of high power TEA CO2 lasers

A new technique is proposed to fine tune a TEA CO₂ laser within the bandwidth of a single ro-vibrational emission line. A tuning range of ±2 GHz off line center is obtained with an emission bandwidth of about 250 MHz and with a total energy output exceeding 1 joule at line center for the P20 (00°1–10°0) line. This technique can be used for single longitudinal mode operation and has the advantage of being directly scalable to higher power lasers.     

间隔可调多波长光纤激光器的实验研究

半导体光放大器(SOA)的非均匀加宽特性对产生多波长激光非常有利。本文对两段式立奥-萨尼亚克(Lyot-Sagnac)滤波器进行了详细的理论分析,实现了一种基于半导体光放大器的新型多波长光纤激光器。它利用立奥-萨尼亚克滤波器的波长选择性,在室温下得到了约18个具有30 dB信噪比的多波长激光输出。波长范围1556~1577 nm。通过调节立奥-萨尼亚克环内的偏振控制器,多波长激光的波长间隔可在两种国际电信联盟(ITU)标准波长间隔(0.4 nm和0.8 nm)间选择。这种构型的光纤激光器具有稳定性好、波长间隔可控、信噪比高等优点。     

A 1550-nm linearly tunable CW single-mode external cavity diode laser based on a single-cavity all-dielectric thin-film Fabry–Pérot filter

A 1550-nm linearly tunable CW single-mode external cavity diode laser (ECDL) based on a single-cavity all-dielectric thin-film Fabry–Pérot filter (s-AFPF) is proposed and realized in this paper. Its internal optical components as well as their operation mechanisms are introduced first, and then its longitudinal mode output characteristic is theoretically analyzed. Afterwards, we set up the experimental platform for the output characteristic measurement of this tunable ECDL; under different experimental conditions, we execute accurate and real-time measurements for the output central wavelength, output optical power, output longitudinal mode distribution, and the line-width of the tunable ECDL in its tuning process. By summing up the optimal experimental condition from the measured data, we obtain the optimal tunable relevant parameters ECDL of the tunable ECDL has a linear mode-hop-free wavelength tuning region of 1547.203 nm-1552.426 nm, a stable output optical power in the range of 40 μW-50 μW, and a stable output longitudinal mode distribution of a single longitudinal mode with a line-width in the range of 100 MHz-150 MHz. This tunable ECDL can be used in environmental gas monitoring, atomic and molecular laser spectroscopy research, precise measurements, and so on.     

Tuning and mode characteristics of the C.W. InSb spin-flip Raman laser determined by use of a Fabry-Perot interferometer

A simple variable length (10–50 cm) air-spaced Fabry-Perot interferometer has been used to calibrate the tuning characteristics of a c.w. InSb spin-flip Raman laser (SFRL). The SFRL output frequency is determined by competition between the spontaneous spin-flip resonance line and the cavity axial modes of the InSb crystal. Over several cavity modes the SRFL is found to tune linearly within ±250 MHz and inside a single mode to ±50 MHz. The tuning rate over several modes is found to be 2.35 cm^-1/kgauss and within a single mode the tuning rate is 1.80 cm^-1/kgauss. Frequency jumps of ≈500 MHz between modes are inferred. Used in conjunction with the observation of known molecular absorption lines as frequency standards, the interferometer provides a calibration of the SFRL suitable for infra-red Doppler limited spectroscopy. of gases. The observed frequency asymmetry in the SFRL output power and the non-linear tuning rate (variable from ≈70-40 MHz/gauss) over a single axial mode show plane-wave cavity theory to be inadequate. These effects can be explained by considering gain controlled refraction induced by a pump beam of gaussian profile. The near resonant dispersion of the refractive index of InSb is inferred from a measurement of the spacing between adjacent peaks in the SFRL output.