Nd:YVO4/KTP激光碘分子超精细光谱和稳频研究

用Nd：YVO4／KTP腔内倍频环形激光器产生的532nm波长激光，探测到了波长在532．170nm至532．200nm范围的一系列碘的多普勒吸收谱线和饱和吸收谱线。理论计算出相应的波长值和超精细谱线结构参数。理论计算值与实验测量数据在较高的精度内相一致。用三次谐波锁定的稳频电路实现了该激光器在碘饱和吸收线超精细分量上的频率稳定。     

偏频锁定0.633μM碘吸收稳频激光

为了满足大尺寸精密干涉测量对干涉信号的信噪比要求，我们研制了偏频锁定氦氖０．６３３μｍ碘吸收稳频激光器，该系统激光的频率不稳定度为５．５×１０－１２（τ＝１０ｓ），系统的频率再现性为４×１０－１１，可连续锁定６个小时以上，无调制输出功率大于０．８ｍＷ。     

633nm He—Ne碘稳频激光波长的国际比对

１９９７年７月,在北京中国计量科学研究院进行了由国际计量局组织的碘稳频６３３ｎｍＨｅ－Ｎｅ激光波长基准的多边国际比对,进行了频率稳定度、频差及相应的压力位移、功率位移和调制位移测量实验。测量工作以ＢＩＰＭＰ３激光器为参考,最后给出以ＢＩＰＭ４激光器为基准的最终测量结果。     

超稳激光的研究

介绍了实现超稳激光和Pound-Drever-Hall（PDH）稳频系统的基本原理,并就削减振动、温度、空气扰动等方面噪声的主要方法进行了讨论。此外,概述了超稳激光的主要应用,介绍了通过超稳激光实现超稳微波源的应用,并提出为实现超稳微波源而自行设计的超稳激光方案和系统设计参数。     

智能双纵模激光稳频系统的研究

为同时满足双纵模氦氖激光器的稳频精度和响应速度要求,提出一种嵌入式智能控制激光稳频系统。以AT89S52为核心,整个系统通过控制激光管的电流大小以改变激光管谐振腔腔长,从而达到稳频的目的;并基于分段式PID控制算法实现了稳频系统的软件开发。经试验证实:该系统满足设计要求,稳频精度保持在10-8以内;在外界强干扰情况下,恢复原来的状态后,激光器在30s内也可以重新稳住。与以往传统的PID控制系统相比较,该系统大大提高了抗干扰能力和响应速度。     

633 nm碘稳频He-Ne激光器研究进展

在长度计量领域,基于饱和吸收技术的633 nm碘稳频He-Ne激光器因其具有波长在可见光范围内,结构简单而紧凑,波长复现性好等优点,作为长度基准在长度实验室和计量实验室得到了广泛应用。对633 nm碘稳频He-Ne激光器进行进一步的研究,对于保持我国长度计量领域的先进性及我国数字计量事业的建设具有重要意义。介绍633 nm碘稳频He-Ne激光器的基本原理、研究现状以及数字化进程,对其发展趋势进行展望。     

激光稳频技术的新发展

本文着重介绍精密计量行业中运用的Ｈｅ－Ｎｅ激光器的稳频技术，并综合了Ｈｅ－Ｎｅ激光器单模、双模稳频技术的现状和发展动向以及新兴的半导体激光器稳频技术。     

激光陀螺数字式稳频方法的研究

提出了一套激光陀螺数字式稳频方案，在理论分析的基础上，设计并制作出数字式稳频硬件电路，同时编写了相应的稳频控制程序。实验结果表明：激光陀螺数字式稳频方法是可行的，且优于传统的模拟式稳频。     

机抖激光陀螺稳频控制技术

激光陀螺的工作中心频率作为激光陀螺的工作计量基准,其频率的稳定性对激光陀螺的测量精度有着直接的影响．稳定激光陀螺工作中心频率最为有效的方法就是采用主动腔长补偿控制．在对腔长控制原理和方法介绍的基础上,提出了将激光陀螺输出光强信号进行交直流分量分离独立控制的方法,并给出了系统的硬件设计框图,最后介绍了软件设计流程．测试结果表明漂移均方差在0．4°·h-1以内,满足系统的使用要求．     

铬原子束激光感生荧光稳频技术理论分析

在铬原子光刻中可采用铬原子束激光感生荧光(LIF)来实现激光频率的稳定,以满足原子光刻对激光频率稳定性的要求。激光感生荧光稳频技术除有很高的稳频精度以外,还可以获得相对于原子共振频率的一定失谐量。本文根据已有的实验条件和参数从铬原子束的速率分布、激光频率与荧光斑点中心横向位移的关系、二象限光电探测器测得的误差信号等方面对铬原子束激光感生荧光(LIF)稳频技术作了理论分析。     

双纵模He-Ne激光器的热稳频技术研究

介绍了双纵模He-Ne激光器的热稳频技术原理,设计了热稳频控制系统,并进行了相关的实验。根据实验结果可知,本热稳频系统实现了将两个纵模频率稳定在增益曲线中心频率对称位置和不对称位置上。根据拍频结果可知,当稳定在对称位置上时,激光器的频率稳定度达10^-10量级;当稳定在不对称位置上、维持频率稳定度10^-10量级时,激光器输出单纵模的功率最高达总功率的80%。     

Optical Frequency Metrology of an Iodine-Stabilized He-Ne Laser Using the Frequency Comb of a Quantum-Interference-Stabilized Mode-Locked Laser

We perform optical frequency metrology of an iodine-stabilized He-Ne laser using a mode-locked Ti:sapphire laser frequency comb that is stabilized using quantum interference of photocurrents in a semiconductor. Using this technique, we demonstrate carrier-envelope offset frequency fluctuations of less than 5 mHz using a 1 s gate time. With the resulting stable frequency comb, we measure the optical frequency of the iodine transition [¹²⁷I₂ R(127) 11-5 i component] to be 473 612 214 712.96 ± 0.66 kHz, well within the uncertainty of the CIPM recommended value. The stability of the quantum interference technique is high enough such that it does not limit the measurements.     

~85Rb原子D_2线饱和吸收谱稳定半导体激光频率

用780nm AlGaAs半导体激光器和差分放大技术,观测了~(85)Rb原子D_2线(5S_(1/2)-5P_(3/2))B分量(5S_(1/2),F=2→5P_(3/2),F=1,2,3)的消多普勒饱和吸收谱。利用一阶导数和三阶导数稳频技术,实现了对AlGaAs半导体激光的稳频,对于1s和10s的取样时间,频率稳定度可达10~(-10)～10~(-11)。     

半导体激光器用铷D2线光电流谱稳频

本文报导了用铷原子７８００Ａ光电流谱来稳定半导体激光器的工作，在光电流谱线的中部发现了有利于稳频的凹陷，将半导体激光器频率锁定在凹陷的中央，估算的频率稳定度为１ＭＨｚ。     

外腔半导体激光器阵列波长稳定的实验研究

自由运行的半导体激光器列阵输出激光谱线较宽、中心波长易漂移.为此,本文采用体全息光栅(VBG)构成外腔半导体激光器阵列(EcLD)系统,利用体光栅能够稳定波长、压窄线宽的特点,从而克服上述缺点.实验表明:采用了VBG外腔反馈后,在最好的情况下,LDA的输出光谱宽度从自由运行时的2.3 nm压窄到了O.96 nm;在测试的环境温度变化范围内(14～3l℃),LDA的峰值波长稳定在体光栅布拉格波长808 nm处,输出光的线宽维持在1.14 nm之下;并且,在测试的偏置电流变化范围内(7-13A)峰值波长和谱宽无明显变化.     

Broadband Intensity Stabilization of a Diode-pumped Monolithic Miniature Nd: YAG Ring Laser

Abstract

We have built an electronic servo system to reduce the intensity noise in a diode-pumped single-mode monolithic Nd: YAG ring laser with a maximum output power of 350 mW. The servo used two stabilization systems operating simultaneously over two different frequency ranges, each of which detected a fraction of the laser output, amplified and phase shifted the detected signals and used the resultant signals to control the current to the laser diode pump. We achieved a reduction in intensity noise of up to a factor of 30 for frequencies up to about 1 kHz, with some noise reduction observable up to about 30 kHz. At frequencies between around 30 and 200 kHz the intensity noise was increased by a factor of approximately 1·4. In the frequency range 200 to 300 kHz, around the relaxation oscillation frequency of 260 kHz, the intensity noise was suppressed, the reduction factor being approximately 14 at 260 kHz.     

Optical properties of Nd:NaLa (WO4)2 single crystal

Nd³⁺-doped NaLa(WO₄)₂ single crystal with a dimension of 20 mm × 40 mm and a good optical quality was grown by Czochralski method. The polarized absorption spectra and emission spectra were measured at room temperature. The absorption cross-section and emission cross-section were presented. The Judd–Ofelt theory, extended to anisotropic system, has been applied to evaluate the intensity parameters Ω_t (t = 2, 4, 6), radiative transition rates A, radiative lifetimes τ_R and fluorescent branching ratios β. The calculated radiative lifetime was compared with the experiment data for the ⁴F_3/2 emitting level. All spectral features are strongly affected by an inhomogeneous broadening connected with the ‘disordered crystal’ character of the title compound.     

Investigation of Errors in Estimates of the Frequency of Signals of Laser Doppler Anemometers Using Wavelet Analysis

A method of processing the signals of laser Doppler anemometers using wavelet transformation is considered. The errors of Doppler frequency estimation obtained from an analysis of the wavelet spectrum of the signal are calculated and the influence of a number of parameters on these errors is investigated. Recommendations for performing measurements are given.