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。     

碘-127稳频640nm氦氖激光器的研究(英文)

使用自行研制的~3He-~(22)Ne激光管,首次在640nm波段发现了碘-127分子强的超精细结构谱线。我们从理论上对这些谱线进行了分类计算,确认它们属于碘-127分子P(10)8-5和R(16)8-5超精细结构能级的跃迁。通过对这些超精细谱线频率间隔的精确测量,从理论上修正了碘-127分子的超精细结构耦合常数。用修正后的耦合常数计算的谱线间隔值与实验值的标准偏差仅为32kHz。用这些谱线中的a_9分量作为频率参考谱线,研制成功了碘-127饱和吸收稳频640nm氦氖激光器,其频率稳定性为8×10~(-12)(平均时间10秒),频率重复性优于1×10~(-11)。并测量了它的波长值。碘-127稳频640nm激光器有可能为复现新米定义和为激光光谱学提供一条新的波长标准。     

碘吸收池的制作工艺

在我们的实验室工作中,经常需要制作碘吸收池来指示 Ar 激光器 5 145A和 5 017A的输出谱线,用以校准染料激光器的输出波长。 制作碘吸收池需采用特殊的工艺。众所周知,碘的升华温度只有30多度,其蒸汽压力与温度的关系为P——碘的饱和蒸汽压,单位(Pa) t——冷端温度,单位(℃) 根     

光栅型光谱仪波长准确度校准方法

针对低压汞灯谱线能量弱且量值无法溯源的难题,本文以1 064 nm单块固体环形激光器作为基频光,经过两次倍频分别得到532 nm、266 nm激光,通过调制转移光谱技术将532 nm激光频率锁定在碘分子超精细谱线上,以此为基础对光栅型光谱仪的波长准确度进行校准。实验结果表明,稳频波长源输出的三波长具有严格的倍数关系,能够准确有效地对光栅型光谱仪波长准确度进行校准,具有很好的实际应用价值。     

外腔激光器实现波长变换的理论及实验

理论上从半导体激光器的速率方程出发,利用其增益饱和效应,提出了光纤光栅外腔半导体激光器实现波长变换的理论模型。利用此模型对入射波为高斯波时的波长变换进行了数值模拟。实验实测了光纤光栅外腔半导体激光器的波长变换前后的谱线,得到带宽 0.1nm,边模抑制比为37.9dB 的激光谱线,并且利用此波长的外腔激光器得到了波长转换间隔为 8nm 的激光谱线。理论分析和实验结果证明,光纤光栅外腔半导体激光器在实现波长变换方面具有很好的线性响应特性。     

以调频光谱学方法和置于环形谐振腔中的碘室锁定612nm激光器

报导了612nm激光器的腔外碘吸收锁定系统。碘吸收室被置于谐振锁定的环形谐振腔内,另一高精细度的参考光学谐振腔则被用来改善激光器的短期频率稳定度。所用的三种锁定系统都采用了调频光谱学方法,不含抖动调制元件。本研究工作获得了612nm处腔外碘吸收的最高信噪比。     

以调频光谱光方法和置于环形谐振腔中的碘室锁定612nm激光器

报导了612nm激光器的腔外碘吸收锁定系统，碘吸收室被置于谐振锁定的环形谐振腔内，另一高精细度的参考光学谐振腔则被用来改善激光器的短期频率稳定度。所用的三种锁定系统都采用了调频光谱学方法，不含抖动调制元件，本研究工作获得了612nm处腔外碘吸收的最高信噪比。     

碘分子超精细谱线的分析计算

本文简要介绍对碘分子超精细谱线的分析方法和编写计算机程序的思路。给出用该程序分析计算的新观测到的~(127)I_2X-B电子态跃迁P(10)8-5带超精细谱线。得到相应的超精细作用常数是:ΔEQq=1949.869±0.499MHz,ΔC=23.06±1.37kHz,ΔD=-4.52±23.29kHz,ΔA=-27.34±18.43kHz。     

采用Zeeman效应与饱和吸收法的激光器稳频

由于塞曼效应中性原子的超精细能级在磁场中会产生塞曼分裂,且对于左旋和右旋圆偏振光原子能级的偏移不同,因此利用Zeeman效应的这种特性与饱和吸收相结合的方法对光栅外腔反馈的半导体激光器系统进行稳频。这种方法能够将激光频率稳定地锁在原子吸收谱线的峰值处,锁频后激光器不易失锁,用于激光冷却铷原子实验。     

532 nm Nd:YVO4/KTP激光器的I2分子吸收谱线的观测及频率稳定的研究

激光二极管抽运的固体激光器可用于光学计量,长度测量,相干光通信,激光雷达等方面,高精度应用要求激光器的频率稳定。碘分子在５３２ｎｍ附近在上百条强的吸收谱线,采用单频Ｎｄ;ＹＶＯ４／ＫＴＰ激光对碘的一些吸收谱线作了观测,并进行了激光频率稳定的研究,这些吸收谱线是１９９７年９月国际米定义咨询委员会推荐作为频标的９组５３２ｎｍ碘吸收谱线之外的新的参考谱线。     

Iodine stabilized dye laser system for frequency measurements in the visible and near IR region of the spectrum

An iodine stabilized dye laser system is described that provides traceable measurement of reference frequencies in the visible spectrum from 540 to 670 nm and in the near infrared at 1.15 /spl mu/m. The system allows calibration of the widely used 633 nm, 612 nm, and 543 nm HeNe laser systems. Also, frequency measurements of a polarization stabilized 1153 nm HeNe laser have been performed via frequency doubling and comparison with the dye system operating on the corresponding 576 nm lines. Studies of the shift sensitivities of the system at various wavelengths of interest are described for variation of iodine cell pressure, laser modulation amplitude, and optical saturation power. The dye system was also stabilized to hyperfine components associated with the 6-3 P(33) iodine transition and compared with a 633 nm iodine stabilized HeNe standard.     

Efficient upconversion-pumped continuous wave Er3+:LiLuF4 lasers

We report on detailed spectroscopic investigations and efficient visible upconversion laser operation of Er³⁺:LiLuF₄. This material allows for efficient resonant excited-state-absorption (ESA) pumping at 974 nm. Under spectroscopic conditions without external feedback, ESA at the laser wavelength of 552 nm prevails stimulated emission. Under lasing conditions in a resonant cavity, the high intracavity photon density bleaches the ESA at 552 nm, allowing for efficient cw laser operation.We obtained the highest output power of any room-temperature crystalline upconversion laser. The laser achieves a cw output power of 774 mW at a slope efficiency of 19% with respect to the incident pump power delivered by an optically-pumped semiconductor laser. The absorption efficiency of the pump radiation is estimated to be below 50%.To exploit the high confinement in waveguides for this laser, we employed femtosecond-laser pulses to inscribe a cladding of parallel tracks of modified material into Er³⁺:LiLuF₄ crystals. The core material allows for low-loss waveguiding at pump and laser wavelengths. Under Ti:sapphire pumping at 974 nm, the first crystalline upconversion waveguide laser has been realized. We obtained waveguide-laser operation with up to 10 mW of output power at 553 nm.     

Confinement effects and hyperfine structure in se doped silicon nanowires

We report a density functional study of the electronic properties and hyperfine structure of substitutional selenium in silicon nanowires using plane-wave pseudopotential techniques. We simulated hydrogen passivated [001] oriented nanowires with a diameter up to 2 nm, analyzing the effect of quantum confinement on the defect formation energy and on the hyperfine parameters as a function of the diameter and of the defect position. We show that substitutional Se in silicon has favorable configurations for positions near the surface with possible formation of chalcogen-hydrogen complexes. We also show that hyperfine interactions increase at small diameters, as long as the nanowire is large enough to prevent surface distortion which modifies the symmetry of the donor wave function. Moreover, surface effects lead to strong differences in the hyperfine parameters depending on the Se location inside the nanowire, allowing the identification of an impurity site on the basis of electron paramagnetic resonance spectra.     

Evidence of small crystallites in milled Fe/Co alloy observed by Mössbauer spectroscopy

Structural and magnetic properties of nanocrystalline Fe_0.67Co_0.33 alloy prepared by high energy ball milling have been studied by x-ray diffraction and Mössbauer spectroscopy. The x-ray diffraction pattern of the sample milled for 160 hours indicates the existence of a single bcc phase. On the other hand, Mössbauer measurements, at different temperatures, show that the milled sample has two magnetic components with the same average hyperfine parameters. One sextet component is associated with large crystallites of bcc Fe_0.67Co_0.33 alloy, stable in vacuum up to 825 K and the other component is attributed to small crystallites of Fe_0.67Co_0.33, alloy having sizes in the range from 10 to 18 nm.     

High-frequency-stability diode-pumped Nd:YAG lasers with the FM sidebands method and Doppler-free iodine lines at 532 nm

The FM spectroscopy technique has been applied to two frequency-doubled Nd:YAG lasers to achieve absolute frequency stabilization against the hyperfine structure components of the rovibronic P(54) 32-0 iodine line at 532 nm. A fractional frequency stability of 2 x 10(-13) tau(-1/2) has been obtained for integration times in the range of 1 ms < tau < 10 s. For longer integration times the stability level remains below 10(-13), reaching a minimum value of 4.6 x 10(-14) at 100 s. This high stability level is, to our knowledge, the best value achieved against iodine lines by this locking method and for a fully transportable system.     

Cross-talk compensation of hyperfine control in donor-qubit architectures

We theoretically investigate cross-talk in hyperfine gate control of donor-qubit quantum computer architectures, in particular the Kane proposal. By solving the Poisson and Schr?dinger equations numerically for the gated donor system, we calculate the change in hyperfine coupling and thus the error in spin-rotation for the donor nuclear-electron spin system, as the gate-donor distance is varied. We thus determine the effect of cross-talk-the inadvertent effect on non-target neighbouring qubits-which occurs due to closeness of the control gates (20-30?nm). The use of compensation protocols is investigated, whereby the extent of cross-talk is limited by the application of compensation bias to a series of gates. In the light of these factors, architectural implications are then considered.     

LASERIX: An open facility for developments of EUV and soft X-ray lasers and applications—Developments of XUV sources using high power laser facilities: ILE, ELI

LASERIX is a high-power laser facility leading to High-repetition-rate XUV laser pumped by Titanium:Sapphire laser. The aim of this laser facility is to offer Soft XRLs in the 30-7 nm range and auxiliary IR beam, which could also be used to produce synchronized XUV sources. In this contribution, the main results concerning both the development of XUV sources and their use for applications (irradiation of DNA samples) are presented, as well the present status and some perspectives for LASERIX.     

低阈值级联双区脊形波导单量子阱激光器

报道了低阈值级联双区脊形波导单量子阱激光器的制备，介绍了它的直流输出特性，光双稳特性，光谱波长调谐和高频调制ｐｓ特性。该激光器激光波长约为８５０ｎｍ调谐宽度为７ｎｍ。     

Direct Laser Patterning of Soft Matter: Photothermal Processing of Supported Phospholipid Multilayers with Nanoscale Precision

Direct laser patterning of supported phospholipid multilayers is investigated. Spin coating is used to fabricate stacked bilayers of 1,2‐dioleoyl‐sn‐glycero‐3‐phosphate (DOPA). Photothermal processing with a focused laser beam at λ = 514 nm allows removal of the coating at predefined positions without causing any significant change in adjacent areas. Moreover, processing with nanoscale precision is feasible despite the soft and fluid nature of phospholipid films. In particular, holes with diameters from 1.8 µm down to 300 nm and below are fabricated by using a 1/e² laser spot size of about 2.5 µm. In addition, patterning is also very flexible and can be carried out over macroscopic length scales and at short processing times. Considering these features photothermal laser processing constitutes a powerful tool for micro‐ and nanopatterning of phospholipid films.     

两段式DFB半导体激光器波长调谐实验研究

采用国产普通折射率耦合型两段式ＤＦＢ半导体激光器进行了波长调谐实验研究，实验结果表明，通过分别调节激光器两段的工作电流，不仅可以使器件单模工作，而且还能进行波长调谐。波长调谐范围为６．２ｎｍ，连续波长调谐范围为０．９ｎｍ。