四频差动激光陀螺稳频系统研究

详细阐述了四频差动激光陀螺无调制光强差稳频系统的电路组成和工作过程,通过理论分析和实验对系统的稳频精度进行了估算,频率作稳定性为1．2×10－9。     

全反射棱镜式激光陀螺双纵模稳频技术

针对全反射棱镜式激光陀螺在单纵模稳频条件下纵模调制信号存在盲区的现象,研究了全反射棱镜式激光陀螺双纵模稳频技术。理论分析了功率调谐曲线的特征,获得了双纵模条件下小抖动调制信号的幅度及相位特性,提出了双纵模稳频控制方案,通过软硬件电路设计,搭建了全反射棱镜式激光陀螺双纵模稳频控制系统。在定温和变温环境下,分别对单纵模稳频与双纵模稳频进行了实验测试。实验结果表明,与单纵模稳频控制方法相比,双纵模稳频技术在稳频精度上提高了60%,陀螺精度也得到了相应的提高。     

机械抖动对机抖激光陀螺稳频装置的影响

分析了机抖激光陀螺中偏频系统通过机械抖动对稳频装置施加作用力的影响.此力主要通过沿抖动切线方向调制卡盘组件,并改变环形腔腔长,引起激光频率相对变化达10-7量级.实验表明,激光功率调制量随着卡盘组件质量增大和偏频量增加而增加,从而影响零偏稳定性.提高卡盘在抖动切线方向的刚度,减少其质量或采用丝杆与槽片点接触等技术措施,能减少机械抖动对稳频装置的影响,另外,对机抖陀螺应选择合适的偏频量.     

四频差动激光陀螺的研制与进展

四频差动激光陀螺原理先进,特别是在消除低转速时的闭锁效应方面具有独特的优点,因而具有强大的生命力,现已成为美国两个主要陀螺公司之一的利顿公司的第二代激光陀螺。在国内,四频差动激光陀螺的研制已经成功地走过了原理样机和实验室样机两个阶段,目前正在进行工程化攻关。本文从四频差动激光陀螺的原理和特点出发,简要介绍近年来国内外四频差动激光陀螺的研制动态,对四频差动陀螺的各种新方案和新进展进行了分析     

四频差动激光陀螺小抖动稳频工作模式判别技术研究

为避免传统光强差稳频方式的缺陷,提出了四频差动激光陀螺小抖动稳频方法。从四频陀螺工作原理出发,分析了小抖动稳频的可行性,其中工作模式判别问题是技术难点。提出三种解决方法：改变左右旋模频率间隔、光强差稳频方式的扫模电路结合、根据陀螺零漂数据来判别,为进一步研究提供了参考。     

四频差激光陀螺由于稳频精度局限等引入的零漂

本文分析了四频差动激光陀螺由于稳频精度局限等原因造成其左右旋陀螺在增益曲线上不对称，并导致比例因子不对称和这种不对称的不稳定从而引入零漂的机理；还分析了影响它们的因素；并代入实验测得的稳频精度值，估测了产生的零漂大小。     

四频差动激光陀螺减小磁效应的新方法

四频差动激光陀螺的磁效应是制约其精度提高的重要误差源之一。从四频陀螺工作原理出发,分析其物理机制,提出一种减小磁效应的新方法。基于光强差稳频思想,通过改变稳频判定标准,选择最佳稳频点;同时采取针对性措施,确保陀螺相关参量特别是总光强的稳定性。实验结果验证了此方法的有效性,对研究者有一定参考意义。     

He-Ne激光稳频技术现状与发展

;激光波长在测量方面的广泛应用决定了激光器输出频率的重要程度.文中分析了各种影响He-Ne激光光源频率稳定性的因素,如温度变化、机械振动以及磁场影响等.还介绍了目前常见的三种稳频技术:蓝姆凹陷稳频法、饱和吸收稳频法和塞曼效应稳频原理.并分析了这些技术各自的优缺点.着重介绍了热稳频法.较之前三种方法,热稳频法的系统结构简单、抗干扰能力强,因此得到了更广泛的应用.最后展望了稳频技术的新发展,即通过检测频率获得误差信号的拍频稳频技术.     

高精度差动放大器AD620构成的四频差动激光陀螺数字稳频系统

为提高光强差稳频精度,采用高精度差动放大器AD620放大微弱光强差信号,利用微控制器TMS320LF2407DSP构建了一套实用四频差动激光陀螺的稳频系统.系统核心采用PID算法,包括确定工作点、扫模、跳模处理等程序.经反复试验,AD620差分增益G=166时控制精度最佳.测试结果表明,该系统的稳频精度迭10-9量级,完全能满足应用要求.     

稳频激光综述

本文简要介绍在计量中应用的各种稳频激光系统的频率稳定度和复现性、激光频率和波长测量的现状以及新的来定义。     

Laser diode frequency stabilization with a fiber ring resonator

To improve the frequency stabilization of laser diode in the laser frequency scanned interferometric metrology, a modified method is proposed by using a fiber ring resonator. The theoretical analysis of this modified method is performed. Moreover, the Pound-Drever-Hall (PDH) technique is employed to obtain the frequency discrimination curve of a fiber ring resonator, whose finesse is 1260 and line-width is 270 kHz. The simulated results show that the curve has a steep slope near the resonant frequency, which proves the sensitivity of this system to the frequency deviation, so the modified method has great potential for the frequency stabilization of a laser diode.     

13.5--Interferometric methods for measuring dispersion in CO2laser oscillations and amplifiers

An interferometric method is described for measuring the phase shifts caused by anomalous dispersion in laser active media under actual oscillating conditions. In addition, some data are presented which show how this method can be used to measure dispersion in a single-frequency 10.6-micron CO2laser plasma. The application of an interferometer of this kind to laser frequency stabilization is also discussed, and an absolute frequency stabilization scheme for CO2lasers is suggested. Because the phase shift observed is an antisymmetrical function about the center of the molecular resonance, it can be used directly as an absolute frequency control discriminant. The resulting frequency control system requires neither amplitude nor frequency modulation of the laser. A modification of a Mach-Zehnder interferometer for the measurement of dispersion in laser amplifiers is also described. This modified interferometer was used to measure phase shift as a function of frequency in an unsaturated traveling-wave CO2amplifier. The oscillographic data resulting from these measurements are shown.     

Frequency stabilization of semiconductor lasers for applications in coherent communication systems

The stabilization of the mean frequency of a single-mode semiconductor laser used under modulation in a FSK heterodyne transmission system is achieved by a novel method. The frequency stabilization scheme locks the laser to one of the resonance frequencies of a Fabry-Perot interferometer (FPI). The laser is weakly modulated at a frequency higher than any signal frequencies. Light reflected from the FPI is detected and synchronously demodulated for feedback and current control of the laser. A laser modulated by a pseudorandom sequence with a rate of 140 Mbit/s and an optical frequency deviation of 280 MHz is stabilized with this method against variations in operating temperature and bias current. The mean optical frequency is maintained within ± 10 MHz for hours. Analysis and experiments confirm that the laser frequency remains stable even when the laser linewidth changes under weak optical feedback.     

Frequency stabilization of gas lasers

The state of the art in the field of frequency stabilization of gas lasers is surveyed. A brief discussion of the methods employed to determine the frequency stability of lasers is followed by a listing of the principle causes of frequency instability. The close relationship existing between the control system design and the laser environment is pointed out. Stabilization techniques based on the use of atomic resonance and on the use of interferometers are discussed in detail. Many of these techniques are capable of achieving long-term frequency stabilities of one part in 10⁹or better, which appears to be entirely adequate for most systems applications.     

Stabilized efficient single-frequency Nd:YAG laser

It is shown how intracavity etalons can be optimally designed for axial mode selection and frequency stabilization of gas and crystal lasers. Relevant laser parameters, required etalon properties, and expected losses are determined. A simple frequency stabilization scheme based on birefringent etalons is described, which does not require laser modulation. Major problems associated with stable single-frequency operation of solid-state lasers are discussed. Using an optimally designed crystal quartz etalon, a Nd:YAG laser could be stabilized to 10^-7in frequency and 2 percent in amplitude. The linearly polarized single frequency TEM00output was 150 mW, which compares to an unpolarized 12-mode output of 400 mW for the bare laser.     

Frequency stabilization of the FM laser

A technique for the frequency stabilization of an FM laser is discussed. This technique employs a stabilization discriminant derived from a residual variation of the phase and amplitude of the small FM laser beat note at the modulation frequency, as the frequency of the FM carrier moves across the Doppler gain profile. A first-order analysis describes the dependence of that stabilization discriminant on δ, the mode coupling coefficient produced by the internal KDP phase modulator, and Γ, the resulting FM modulation index. Experimentally, a 50-mW He-Ne FM laser was frequency stabilized to better than one part in 10⁸on a long-term basis. In addition, the beat note at the modulation frequency was suppressed by 40 dB from its free-running value.     

Frequency stabilization of laser diode using a frequency-locked ring resonator to acetylene gas absorption lines

The frequency stabilization of a 1.5 mu m distributed-feedback (DFB) laser diode using a planar lightwave circuit (PLC) ring resonator whose resonant frequency is locked to /sup 12/C/sub 2/H/sub 2/ and /sup 13/C/sub 2/H/sub 2/ gas absorption lines is described. The resonant frequency of PLC ring resonator was stabilized within a 5 MHz peak-to-peak fluctuation. With this ring resonator the outer frequency fluctuation of the DFB laser diode was stabilized within 10 MHz at every resonant frequency at 5 GHz intervals. The stability demonstrated is as good as the method using molecular absorption lines as a reference. The stabilized frequency can be selected at any point on the optical resonant peaks of the optical resonator.<>     

Two-mode multiline laser stabilization using a Fabry-Perot filter under analog and digital computer control

A scanning Fabry-Perot interferometer, servolocked to one of the output frequencies of a multiline laser, is used as a tracking filter so that a second servoloop can accurately stabilize that laser line to features of its intensity-versus-frequency profile. More stable locks occur where two longitudinal modes lase simultaneously than where the single-mode line intensity is maximized. Both analog and digital servoloops have been used for stabilizing a continuous-wave CO laser cavity. The microcomputer-aided digital stabilization yields the more reliable frequency locks and needs negligible frequency dithering. It has produced short-term (<1s) laser linewidths less than 100 kHz and long-term (>100 s) instability estimated as 80 kHz at a laser operating frequency of 55 THz in a noisy laboratory environment.     

环形腔光纤激光器边带偏振不稳定性

为研究双折射光纤的高功率环形腔光纤激光系统输出稳定性,提出了一种可能存在的矢量调制不稳定现象——边带偏振不稳定性(SPI)。结合偏振不稳定性与边带不稳定性的研究方法,建立了偏振光在线性双折射掺杂光纤的环形腔中传输时满足的非线性薛定谔方程,并求得了高双折射光纤中信号光偏振方向与主轴重合时扰动边带的解析解。研究结果表明,在正常色散情况下,沿主轴偏振的信号光在环形激光器中传输时,各阶扰动边带所获得的峰值增益随着信号光功率的变化而呈锯齿状分布,并随功率的增加而趋于一稳定值。