半内腔He-Ne激光器的调整技巧

介绍了半内腔式He-Ne激光器的结构及调整的技巧,测量了在不同放电电流以及不同腔长条件下激光器的输出功率,得到了最佳的放电电流. 半内腔式He-Ne激光器的应用,有助于学生了解激光器的工作物质、谐振腔等主要组成部分,也促进了学生对激光理论的进一步理解.     

基于飞秒光频梳的双频He-Ne激光器频率测量

利用光纤飞秒光频梳和外腔可调谐半导体激光器, 建立了一套双频He-Ne激光器频率测量系统. 选用铷钟作为系统的频率基准, 通过将外腔半导体激光锁定至光频梳使得其频率溯源至铷钟, 再利用外腔可调谐半导体激光与双频He-Ne激光器输出的正交偏振激光拍频, 同时测量两路正交偏振激光频率. 将可调谐半导体激光器锁定至光频梳第1894449个梳齿, 其绝对频率为473612190000.0±2.7 kHz, 相对不确定度为5.7×10^-12. 对商品双频He-Ne激光器进行频率测量实验, 双频He-Ne激光器水平方向偏振激光频率均值为473612229934 kHz, 竖直方向偏振激光频率均值为473612232111 kHz, 平均时间为1024 s的相对Allan标准差为5.2×10^-11, 频差均值为2.177 MHz, 标准偏差为2 kHz.     

基于猫眼谐振腔激光器的激光基本特性综合实验系统

基于猫眼谐振腔结构的He-Ne激光器,设计了激光基本特性综合实验系统. 使用该系统可以同时实现激光基横模与高阶横模观察、纵模观察、频率分裂及模竞争实验的演示.     

双纵模稳频氦氖激光器的光谱与频率复现性分析

对双纵模稳频氦氖激光器的光谱及其频率复现性进行了理论估计,进行了633 nm碘稳定氦氖激光器的拍频实验,实验采用内腔激光器,并采用双纵模稳频的方法,通过观测激光器的两个偏振态互相垂直的相邻纵模的输出,并使二者稳定到功率相等的参考点处,获得激光稳定输出。实验通过观察双纵模稳定激光的模式输出,分析了影响激光频率复现性与频率稳定度的因素,测量了稳定激光的功率和频率稳定度。通过拍频测量,对激光器的频率复现性进行了分析,复现性用频差可以达到(1～2)×10-8量级。通过实验表明,双纵模稳频氦氖激光器的频率复现性完全符合用于长度精密测量的稳频激光器的要求,激光器可以很稳定地工作,稳定度用阿伦偏差表示可以达到10-10量级,可以作为实用的稳频激光标准。     

峰值稳频横向塞曼He—Ne激光器

本文主要介绍一种峰值稳频横向塞曼He-Ne激光器。实验发现激光器输出相互垂直振动的光拍频频率的最大值对应激光器增益轮廓中心。利用调制的方法将激光器输出激光的频率稳定在增益轮廓中心。与国家计量测试研究院的碘吸收稳频标准激光器拍频,频率稳定度为1×10~(-9)。     

基于双折射双频激光器中的调频回馈位移测量研究

提出了一种基于双折射双频激光器中的调频回馈效应的位移测量系统，并在实验和理论两方面进行了研究.实验中保持回馈外腔长度不变，将一四分之一波片置于激光器内腔中，调制内腔长度，激光器的中心频率发生改变，激光器输出强度将发生周期性的变化.研究发现激光强度曲线的波动频率正比于回馈外腔长度与内腔长度之比.当该位移测量系统的外腔长度是内腔长度的6倍时，被测物体每移动半个光波长，激光强度波动12次，系统分辨率可以达到二十四分之一光波长.理论分析与实验结果相符合.研究表明该位移测量系统具有高分辨率、大测量范围、可工作于任意回馈水平等特点. 关键词： 调频回馈 位移测量 双折射双频激光器 强度波动频率     

纵模分裂式正交偏振双频He-Ne激光器

在激光器谐振腔中放入单轴石英晶体,由于石英晶体对o光和e光的折射率的不同,所以,在同一谐振腔中o光和e光有不同的光程和谐振频率.将其称之为模式分裂效应.利用这一效应可以制成频率达几十兆赫兹的双频激光器.针对原有理论与实验结果之间的某些差异,建立了一套分析该种类型双频激光器的理论.根据所建立的理论着重分析了谐振腔光轴与晶轴夹角α对激光器频差的影响.并绘出了He-Ne激光管L<150nm和150nm相似文献   

猫眼腔激光器的横模变换与频率分裂

为了产生多种激光横模,以前的系统相对比较复杂,而且一般只能产生基横模和低阶横模,很难产生高阶横模,同时也很难观察到模竞争中一个频率抑制另一个频率的变化过程。基于猫眼谐振腔激光器和频率分裂技术,提出了一种新型的激光原理综合实验系统。该系统利用猫眼逆向器作为He-Ne激光器的一个腔镜,通过调节猫眼逆向器中两镜片间距可输出包括基横模、低阶横模、高阶横模在内的十余种典型横模,并可完成纵模、偏振、出光带宽等多种激光基本特性的实验。同时在基横模状态下,利用谐振腔内加入的石英晶体片可实现激光频率分裂及其频差调节。在此基础上又可实现完整的模竞争过程的观察。     

双频氦氖激光回馈位移测量系统的实验与应用研究

研究了一种全新的纳米尺度位移测量系统。将双折射元件插入He-Ne激光器谐振腔内产生频率分裂效应，使原本单模谐振的激光器输出变成了频差可调的2个正交偏振频率（o光和e光），而形成双频激光器。在激光谐振腔外放置沿激光轴线位移的反射表面，将输出的激光束反射回腔内，以便对激光的光强进行调制，可实现高分辨率非接触式可判向位移测量。提出了一种细分方法，该方法突破了传统干涉系统的衍射极限（1/2波长）。对于633nm波长He-Ne激光，本系统的理想分辨率为1/8波长（约为79nm）。     

激光器内腔频差对双折射外腔激光回馈系统输出影响的理论及实验研究

玻璃材料的内应力关系及所在系统的稳定性、安全性和可靠性,是精密加工领域的重要问题.基于双折射外腔激光回馈效应的应力测量技术以其先进新颖的测量原理受到普遍关注.传统理论普遍认为双折射回馈系统中激光器的输出相位仅由外腔相位延迟决定,而将测量误差归因于外腔镜的非线性运动.本文结合正交偏振激光原理和三镜腔等效模型,测量了激光器的内腔双折射引起的频差大小,进行了频率调谐回馈实验,并根据结论计算了内腔频差对外腔相位延迟测量结果的影响,发现激光器的输出相位由外腔相位延迟、内腔频差、外腔长度共同决定.本文总结了内腔和外腔各向异性共同作用下激光器正交偏振态的相位特性,补充了激光回馈的物理内容,对于应力-双折射、位移、距离等重要参量的精确测量,都具有重要指导意义.     

激光准直Cr原子束的实验研究

利用多普勒原理对Cr原子束进行横向准直.应用激光感生荧光技术稳定激光器的频率，把激光器的中心频率稳定在偏离Cr原子共振中心频率-5±0.26MHz的位置.根据理论计算出准直激光束的最小尺寸为13.7mm.根据实验数据选择合适的参数，实现利用多普勒原理横向准直Cr原子束，使原子束的横向分布缩小到原来的1/3. 关键词： 激光准直 激光感生荧光稳频 多普勒冷却     

Rb原子的激光囚禁

用饱和吸收光谱法对二极管激光器进行稳频,使激光器的有效线宽小于１ＭＨｚ,并利用声光调制器使激光的频移量得到控制,满足了激光冷却与因禁原子对激光频率生和频 量的 Ｒｂ原子的激光囚禁。     

A Simple Frequency Lock of Green YAG Laser to Dispersion Line of the Linear Absorption Spectrum of Iodine Molecules Utilizing an Acousto-Optic Frequency Shifter

Frequency of a 532 nm emission line of a diode-laser-pumped Nd:YAG laser is stabilized by lock of the output line to the linear absorption line of iodine molecules. The stabilization method is very simple utilizing the frequency shift caused with an acousto-optic modulator. The laser frequency was stabilized at the zero-crossing point of the second-derivative of the dispersion curve. Instability obtained by the error signal is affected by the phase-characteristics of detectors, which results in 3^*10^-8.     

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.     

Development of multiple laser frequency control system for Ca<Superscript>+</Superscript> isotope ion cooling

We here developed and evaluated a laser frequency control system which synchronizes the laser frequency to the resonance of target Ca ⁺ isotope ion whose having more than 8 GHz of isotope shift based on the Fringe Offset Lock method for simple operation of ICPMS-ILECS (Inductively Coupled Plasma Mass Spectrometry - Ion trap Laser Cooling Spectroscopy) The system fulfilled the minimum requirements of four slave lasers stability for Doppler cooling of Ca ⁺ ions. A performance of the system was evaluated by cooling ⁴⁰Ca ⁺ ions with the stabilized slave lasers. All the stable even Ca ⁺ isotope ions were trapped and their fluorescence was observed by switching laser frequencies using the system. An odd calcium isotope ⁴³Ca ⁺cooling was also succeeded by the control system.     

锶原子Doppler冷却中再抽运光对原子俘获影响的理论和实验研究

本文主要研究锶原子光钟Doppler冷却过程中再抽运光对俘获冷原子参数的影响,实验上测得再抽运光光强和失谐跟所俘获原子数目的关系,并且测得了在同时注入再抽运光707 nm和679 nm后使俘获冷原子的数目提高了17倍,分析了再抽运光的失谐对俘获原子数目的影响,测得了再抽运光707 nm在失谐5 MHz的情况下俘获原子数目的波动小于3‰. 关键词： 光频标 激光冷却与俘获 原子俘获率     

The applications of the stark effect to the stabilization of the CO2 laser and the submillimeter laser

Methods based on the Stark effect are described for dither-free frequency stabilization of the optically pumped submm laser. The CO₂ pump laser was stabilized using a Stark Lamb dip signal of the submm lasant in an external Stark cell. An estimated frequency stability (f/f) better than ±1.4×10^–8, for one hour recording, was obtained by this method. The frequency of the submm laser was stabilized using the d.c. and a.c. Stark effects for a metal-dielectric rectangular waveguide laser. An estimated frequency stability of ±6×10^–8 was obtained for 119 m line of CH₃OH laser for one hour recording.     

Frequency stabilization and measurements of 543 nm HeNe lasers

In this paper we report our investigations on the frequency stabilization and frequency measurements of 543 nm HeNe laser. It contains following four different works. (1) Using a metal laser tube we have built an iodine-stabilized 543 nm HeNe laser by the Frequency-Modulation (FM) spectroscopy. The signal-to-noise ratio of the hyperfine spectrum reached 2 × 10^–12 at 1 s sampling time. (2) We have built a compact iodine-stabilized 543 nm HeNe laser system using the third-harmonic locking technique. Stability better than 1 × 10^–12 for sampling time >1 s is obtained. We also suggest the b₁₀ line for the future recommendation. (3) We constructed the Lamb-dip stabilized He-²⁰Ne and He-²²Ne lasers and measured their frequency stability, reproducibility, and absolute frequencies. The results suggest that the Lamb-dip stabilized lasers are appropriate for secondary wavelength standards. We have also deduced the isotope shift of Ne atom at 543 nm. (4) We have developed two two-mode stabilized 543 nm HeNe lasers using the bang-bang control method. The Allan variance is 1 × 10^–11 at 1 s sampling time.     

Raman and IR reflection micro‐spectroscopic study of Er:YAG laser treated permanent and deciduous human teeth

Permanent and deciduous human teeth treated by a dental Er‐doped yttrium‐aluminium‐garnet pulse laser (λ = 2940 nm) as well as by classical drilling tools under conditions typical of the clinical practice were studied by ultraviolet Raman and Fourier transform infrared (FTIR) reflection microspectroscopy. Enamel was analyzed by both spectroscopic methods, whereas dentine was studied only by FTIR reflection because of the high level of photoluminescence continuum background even when a wavelength of 325 nm was used in inelastic light scattering experiments. The applied energy and pulse frequency of the dental laser varied between 200 and 500 mJ and between 10 and 30 Hz, respectively. The most important result is that after the laser treatment, the hydroxyapatite structure in both permanent and deciduous enamel is preserved: the apatite Ca‐P‐O framework remains intact, and the content of channel OH^‐ groups is not changed within experimental uncertainties. The calcium‐phosphate framework of dentine also exhibits negligible laser‐induced changes. The only alterations in enamel induced by laser as well as by mechanical drilling are reduction of the amount of CO₃^2‐ in apatite and changes in the protein conformation. The laser impact on the organic material and carbonate groups is strongest for laser power of 8 W; for powers of 4 or 5 W, the combination of higher pulse energy and lower pulse frequency has less impact than the combination of lower energy and higher frequency. No differences between deciduous and permanent teeth in their resistivity to laser irradiation with λ = 2940 nm were detected. Copyright © 2013 John Wiley & Sons, Ltd.     

New FIR laser lines and frequency measurements for optically pumped CD3OH

Twenty new cw FIR laser lines in CD₃OH, optically pumped by a CO₂ laser, are reported. The frequencies of 39 of the stronger laser lines were measured relative to stabilized CO₂ lasers with a fractional uncertainty, as determined by the reproducibility of the FIR frequency itself, of 2 parts in 10⁷.Contribution of the U.S. Government, not subject to copyright.