Stable Narrow Linewidth 689nm Diode Laser for the Second Stage Cooling and Trapping of Strontium Atoms

We report stable narrow linewidth laser systems based on self-developed Littman configuration external cavity diode lasers （ECDLs）. The frequency of the ECDL is stabilized to a high fineness ultralow-expansion glass reference cavity with the Pound-Drever-Hall technique. By heterodyne beating of two identical systems, we conclude that the linewidth 4.3× 10^-14 at an averaging measurement time. of each ECDL is reduced to lower than 150 Hz and its frequency stability reaches time of 1 s, the averaged long-term frequency drift is less than 0.2 Hz/s over 30 h     

用周期极化KTP晶体高效倍频获得稳定461nm激光

实验采用准相位匹配的PPKTP晶体对922nm连续激光进行外腔谐振倍频,获得稳定461nm激光.实验装置采用一体化环形腔没计,实现最大耦合转换效率达73.3%,获得208 mW的461 nm蓝光输出.实验结论中通过分析,修正损耗误差,得到最佳耦合腔镜反射率,并深入讨论了耦合腔镜的两种反射率对倍频输出功率和效率的影响,同时就晶体吸收效应和热透镜效应对倍频试验的影响也进行了深入研究.     

Nd:YVO4/KTP环形倍频激光器三次谐波稳频碘吸收谱线超精细结构的研究

采用三次谐波稳频的方法,对Nd：YVO4／KTP环形倍频激光器的碘吸收谱线的超精细结构进行研究,在实验上观测到的两组谱线的超精细结构与理论值基本相符,其中,观测到的R(70)36-1谱线属于第一激发态跃迁,这一结果尚未见报道。     

利用自相位延迟方法测量单块腔反馈半导体外腔激光器的线宽

提出了采用单块折叠法布里-珀罗(F-P)腔作为外腔反馈元件实现窄线宽半导体激光器,采用单块腔的光学反馈来锁定外腔激光器,使用自相位延迟法测量该窄线宽激光器的线宽。实验结果表明,激光器线宽小于35kHz。实验还观测到由于单块腔耦合面上各耦合点的几何量和物理量误差不一样,随着折叠面兼输入输出耦合面上的耦合点的变化,外腔激光器的线宽发生改变。     

Achieving strong doubling power by optical phase-locked Ti:sapphire laser and MOPA system

We show two external cavity-enhanced second-harmonic generations of 922 nm with periodically poled potassium titanyl phosphate crystal,whose doubling cavities are locked separately with Hansch-Couillaud and intra-modulation methods.The outputs of second-harmonic generation reach 310 mW,54.8%of the conversion efficiency from the Ti:sapphire laser with the crystal length of 10 mm,and 208 mW,59% of the conversion efficiency from the MOPA system with the crystal length of 30 mm.It consists of heterodyning the Ti:sapphire laser and the MOPA system,and compares the phase of the beat frequency signal with the phase of a reference RF local oscillator.The resulting phase error is used as a feedback signal and fed back to the reference cavity of the Ti:sapphire laser to lock the two lasers in phase.A stable blue power of 520 mW is obtained,which supplies enough power for the cooling and trapping step of the strontium (Sr)optical lattice clock.Four stable isotopes of Sr, 84 Sr, 86 Sr, 87 Sr,and 88 Sr,are detected by probing the laser during a strong 460.7-nm cycling transition(5s 21 S0?5s5p 1 P1).     

A Hertz-Linewidth Ultrastable Diode Laser System for Clock Transition Detection of Strontium Atoms

The frequencies of two 698 nm external cavity diode lasers （ECDLs） are locked separately to two independently located ultrahigh finesse optical resonant cavities with the Pound Drever-Hall technique. The linewidth of each ECDL is measured to be -4.6 Hz by their beating and the fractional frequency stability below 5 × 10^-15 between 1 s to lOs averaging time. Another 698nm laser diode is injection locked to one of the cavity-stabilized ECDLs with a fixed frequency offset for power amplification while maintaining its linewidth and frequency characteristics. The frequency drift is H1 Hz/s measured by a femtosecond optical frequency comb based on erbium fiber. The output of the injection slave laser is delivered to the magneto-optical trap of a Sr optical clock through a iO- ta-long single mode polarization maintaining fiber with an active fiber noise cancelation technique to detect the clock transition of Sr atoms.     

DESIGN OF A 532nm Nd:YVO4/KTP SINGLE-FREQUENCY LASER

A model of the laser-diode pumped solid-state laser is developed to deduce the minimum average radii of the pump beam in the solid medium, since the smaller the cavity waist, the higher the laser output power is expected to be. With an appropriate coupling system consisting of the collimating lens, prism pair and focusing lens, a diode-pumped single-frequency Nd:YVO₄/KTP intracavity frequency-doubling cw laser has been demonstrated through the precise temperature control of the Nd:YVO₄ crystal, the KTP crystal and the diode laser. The 532nm single-frequency output power of 40.4mW (in fact 55mW if the reflection loss of the triangular prism is taken into account) is obtained for an incident power of 515mW. It is derived theoretically and is verified in experiment that the frequency drift of the free-running laser can be reduced by increasing the cavity length.     

用单块激光器和环形外腔获得稳定的532 nm激光

采用单块半非平面Nd:YAG单频环形激光器和环形外腔倍频技术，获得了单频功率249.5mW的532nm波长的绿光输出，倍频效率43.2%，实现了倍频腔与激光器之间的跟踪锁定，倍频光功率稳定性优于1％，理论计算与实验结果一致。     

用空间频率参量研究激光束特性

本文提出了一种新的方法,用空间频率参量解亥姆霍兹微分方程来获得激光束特性的解析数学描述,并从空间频率参数出发定义了光束束散角和激光束腰斑最小极限值。与用衍射积分方程所得解相比较,结果一致。     

Decreased vibrational susceptibility of Fabry--Perot cavities via designs of geometry and structural support

Ultra-stable optical cavities are widely used for laser frequency stabilization. In these experiments the laser performance relies on the length stability of the Fabry--Perot cavities. Vibration-induced deformation is one of the dominant factors that affect the stability of ultra-stable optical cavities. We have quantitatively analysed the elastic deformation of Fabry--Perot cavities with various shapes and mounting configurations. Our numerical result facilitates a novel approach for the design of ultra-stable cavities that are insensitive to vibrational perturbations. This approach can be applied to many experiments such as laser frequency stabilization, high-precision laser spectroscopy, and optical frequency standards.