一种新型激光陀螺的检测方法

本文通过对新型四频差动激光陀螺输出信号的分析,给出了一种适应新型四频差动激光陀螺输出信号的检测方法。通过APD和高频低噪声前置放大器实现光电接收,通过集中选频放大电路进行滤波和放大,然后采用模拟乘法器实现自乘检波,并根据该方法设计了实际的检测电路。采用直管四频激光器的背向输出来模拟新型四频差动激光陀螺的输出,对电路进行了实际测试。通过测试,验证了检测电路方法的可行性。     

FUZZY-PID在激光陀螺稳频控制中的应用研究

在分析环形激光陀螺光强控制系统原理的基础上 ,针对自行研制的激光陀螺 ( RLG)计算机稳频控制系统的情况 ,研究了 FUZZY- PID与常规 PID控制算法 ;介绍了一种应用模糊推理功能实现 PID参数自整定的控制器 ,它是在常规 PID调节器的基础上 ,采用模糊推理思想 ,根据不同的 E和 EC,对 PID参数 KP、KI、KD 进行在线自整定的模糊控制器。仿真结果表明 :系统的动、静态性能都符合指标 ,该算法是实现激光光强控制进而完成激光频率控制较理想的控制算法。     

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。     

1.5μm光纤通信波段乙炔稳频激光技术研究进展

1.5μm乙炔饱和吸收谱线是国际计量委员会(CIPM)正式推荐的光纤通信波段复现‘米’定义的频率参考标准。乙炔稳频激光依据稳频方法可分为线性吸收和饱和吸收两大类,饱和吸收相比线性吸收,能够消除乙炔分子的多普勒效应,获得线宽更窄、频率稳定度和复现性更高的稳频激光,1s频率稳定度能够达到10^-13量级,波长漂移为10^-12量级。利用13C2H2(ν1+ν3)P(16)谱线,研发的微型气室有望实现稳频激光的全光纤链路传播,为高度集成化、抗干扰能力强的稳频激光源提供了新的发展方向。高性能的1.5μm近红外稳频激光直接为密集波分复用系统、精密光纤传感等多个领域提供波长参考源,结合飞秒激光频率梳技术可进一步完善光纤通信中激光波长量值传递溯源体系,提升激近红外波段光波长的测量能力,为光纤波段的精密测量提供量值保障。     

基于FPGA和DSP的激光陀螺信号处理电路设计

研究机械抖动激光陀螺的信号读出系统,设计激光陀螺的信号处理电路。光电转换后的微弱电流信号经过前置放大电路转化为电压方波信号,在FPGA中进行鉴相解调以及可逆计数,最后由DSP实现机抖偏频解噪和低通数字滤波。与激光陀螺联合测试并将结果输出至上位机,结果表明设计的电路实现了对激光陀螺输出信号的有效采集,满足激光陀螺功能测试的需要。     

基于光频梳的乙炔稳频1542 nm激光波长测量研究

利用光频梳对稳频激光波长进行测量是建立基于光频梳的波长基标准的必经程序。为了建立基于光频梳的波长标准,并为开展激光波长校准工作提供技术准备,利用自研光纤光频梳对乙炔稳频1542 nm激光波长进行了测量。利用光频梳产生参考激光与待测激光差拍,通过简单的代数关系获得了乙炔稳频激光的绝对频率和真空波长,并与相应的国际推荐值进行了对比。实测获得的乙炔稳频激光的真空波长值为1542.38 371 235 742 nm,在CIPM给定的不确定度范围内,秒稳定度为4.13×10-13。两台不同的光频梳对乙炔稳频激光波长的测量结果具有高度一致性,进一步证明了光频梳对激光波长的测量准确性。本研究对于顺应国际长度基标准发展趋势,加速光频梳在激光波长测量领域的应用进程具有重要意义。     

用于塞曼热稳频的自组织自适应预测控制系统

塞曼热稳频广泛应用于双频激光干涉仪中,但稳频调节器的设计存在建模困难和调整工作量大的缺点。本文提出一种非参数化自组织建模的预测控制算法实现稳频控制,并进一步引入自适应算法消除模型误差。开发了可通用于各类塞曼热稳频系统的控制软件,成功地在幅值稳频和频差稳频塞曼激光器上实现了全自动热稳频。通过和中国计量科学研究院标准I     

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。     

全内腔式632.8nmHe—Ne激光器频率稳定的新方法

本文探讨了全内腔式632.8nm He-Ne激光器频率稳定的必要条件,对稳频原理进行了较详细的阐述,提出了检测激光管温度与提取激光输出信号相结合的稳频方法。通过实验获得了满意的结果。     

氦氖激光稳频原理和拍频真空波长检测

He-Ne稳频激光广泛地应用在精密干涉测量中,本文论述He-Ne兰姆凹陷稳频激光,He-Ne兰姆凹陷稳功率激光,0.633微米碘稳频激光、偏频锁定碘饱和吸收稳定0.633pm激光系统和He-Ne双频稳定的激光器的稳频原理及如何用拍频比较法测量它们的波长。     

基于光学锁相环的高稳定度激光稳频方法研究

报道了一种基于光学锁相环的高稳定度激光稳频方法,用于提高可调谐外腔半导体激光器(TECDL)的频率稳定度和准确度。自行研制的光学锁相环电路采用数字鉴相与差分运算相结合的方式获得高灵敏度的鉴频鉴相误差信号,并通过高速模拟PID实现整个系统的闭环锁定。利用该光学锁相环系统进行了TECDL偏频锁定至光学频率梳(OFC)的实验,实验结果表明环路锁定后拍频频率波动在±0.3Hz范围内,偏置频率为50MHz时,光学锁相环系统在1s和1000s积分时间的相对阿伦方差分别为1.5×10^-9和8.5×10^-13。系统锁定后,拍频线宽由500kHz压缩至2kHz。该研究表明采用基于光学锁相环的激光稳频方法可以实现亚Hz级的激光频差控制,通过将TECDL偏频锁定至高稳定度的参考激光源可显著提高其频率稳定度,使其能够满足超精密测量、冷原子/离子干涉测量等领域对激光频率稳定度和准确度的要求。     

Frequency shifts of iodine stabilized He-Ne lasers at higherharmonic order stabilization

The frequency shifts of an ¹²⁷I₂ stabilized He-Ne laser at 633 nm have been measured at the third, fifth, and seventh harmonic stabilization using a digital signal processing lock-in amplifier. The observed frequency shifts confirmed the previous theoretical prediction that the laser frequency depends on the harmonic order of stabilization. The lower effects of modulation amplitude shift, power shift, and iodine pressure shift at the fifth harmonic stabilization indicate a potential improvement of the frequency reproducibility of the laser standard. A model is suggested to describe the power shifts of the laser. The mechanism explains the lower power shift of some lasers when they are operated at relatively high intracavity power     

镱离子光钟的多波长数字PID激光稳频系统

针对镱离子光钟实验中激光冷却并操控离子时,激光器频率漂移影响原子钟系统的问题,基于数字PID控制方法,设计了一种新的多通道频率-数字信号转换稳频方法,将多路多波长激光频率锁定在波长计的参考频率上。对激光器锁定前和锁定后的频率进行一定时长的数据采集及数据对比,激光频率漂移由800 MHz控制在± 0.8 MHz,激光频率稳定度由9.29 × 10^-10@1 s优化至2.79 × 10^-10@1 s,频率千秒稳达到3.85 × 10^-12。该系统简单、易实现,具有小型化、适应性强的优点。     

Resonator fiber optic gyro employing a semiconductor laser

Resonator fiber optic gyro (RFOG) based on the Sagnac effect has the potential to achieve the inertial navigation system requirement with a short sensing coil. Semiconductor laser is one of the key elements for integration and miniaturization of the RFOG. In this paper, an RFOG employing a semiconductor laser is demonstrated. The model of the laser frequency noise induced error in the RFOG is described. To attenuate the laser frequency noise induced error, active frequency stabilization is applied. An online laser frequency noise observation is built, as a powerful optimum criterion for the loop parameters. Moreover, the laser frequency noise observation method is developed as a new measurement tool. With a fast digital proportional integrator based on a single field programmable gate array applied in the active stabilization loop, the laser frequency noise is reduced to 0.021 Hz (1σ). It is equivalent to a rotation rate of 0.07°/h, and close to the shot noise limit for the RFOG. As a result, a bias stability of open-loop gyro output is 9.5°/h (1σ) for the integration time 10 s in an hour observed in the RFOG. To the best of our knowledge, this result is the best long-term stability using the miniature semiconductor laser.     

~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)。     

Stabilization of an embedded fiber optic Fabry-Perot sensor forultrasound detection

A method is proposed to stabilize an intrinsic fiber optic Fabry-Perot interferometric sensor embedded in a solid material for the purpose of detecting ultrasound. Without stabilization the interferometer drifts out of quadrature due to the presence of low-frequency dynamic strains. Stabilization is achieved by using active homodyne stabilization which tunes the laser frequency to maintain quadrature. A control loop shifts the laser frequency by 10 GHz at rates less than 25 Hz in order to compensate for induced drifts. The stabilization procedure was tested for a sensor embedded in an epoxy plate. Ultrasonic pulses, generated by a 5 MHz piezoelectric transducer, were detected with the embedded fiber sensor stabilized in the presence of applied low frequency strains. Improvements in sensitivity which result from stabilization are demonstrated. Additionally, a simulated acoustic emission signal, generated by a lead pencil break (Hsu-Neilson source), was detected with the sensor stabilized in the presence of dynamic strains     

Diode-laser frequency stabilization by two-frequency Doppler-broadened absorption spectroscopy

We demonstrate a robust method for frequency stabilization of a diode laser by two Doppler-broadened absorption spectra of the cesium D2 line. This technique employs an acousto-optical modulator to generate another frequency component from a diode laser to perform the spectroscopy. The 852-nm diode laser with frequency stabilization at the zero crossing of the error signal showed a peak-to-peak fluctuation of 800 kHz compared with a frequency-stabilized femtosecond laser over a 2-h period. This frequency-locking method is free of modulation and can be applied to frequency discriminators as well as to atomic resonances.     

Use of the beat frequency between two modes for frequency stabilization of internal-mirror lasers

We present a simple method of frequency stabilization of a laser with two orthogonal modes that uses the effects of anomalous dispersion at the active line. The result of this effect is that the frequency difference between oscillation modes varies during the frequency tuning along the Doppler line of the transition and has its minimum or maximum when the modes are symmetrically placed around the central part of the gain curve. We applied the semiclassical approach to describe the laser, and we established the rules for laser parameters to obtain the most convenient conditions for stabilization. We stabilized the thermally compensated experimental laser tube and reached frequency stabilities of 3 × 10(-9) and 3 × 10(-10) for integrating times of 1 and 134 s, respectively.     

半导体激光器稳频综述

在冷原子干涉实验中需要用激光冷却并操控原子,因此对半导体激光器频率的稳定性要求较高。由于半导体激光器本身线宽较大,功率稳定性差,还可能产生慢漂和跳模等现象,故需对半导体激光器进行稳频。本文介绍了饱和吸收谱稳频、波长调制稳频、调制光谱稳频、调制转移光谱稳频、双色激光稳频、频率电压转换稳频6种冷原子干涉实验中常用的稳频方法,分别阐述了各方法的原理、特点、适用领域,为半导体激光器的实际应用提供了参考。