Efficient passively Q-switched laser operation of Yb in the disordered NaGd(WO4)2 crystal host

Efficient passively Q-switched laser operation of the disordered Yb:NaGd(WO(4))(2) crystal is demonstrated for the first time to our knowledge with a Cr(4+):YAG saturable absorber by diode end pumping. 2.05 W of average output power at a pulse repetition frequency of 13.3 kHz was obtained at an absorbed pump power of 7.7 W, with a slope efficiency of 40%. The energy and duration of the generated laser pulse were 154 microJ and 33 ns, respectively, corresponding to a peak power of 4.67 kW. In continuous-wave operation, the Yb:NaGd(WO(4))(2) laser yielded an output power of 5.5 W with an optical-optical efficiency of 51%.     

Output-coupling-dependent polarization state of a continuous-wave Yb:YCa4O(BO3)3 laser

High-power continuous-wave laser operation was demonstrated with a y-cut Yb:YCa(4)O(BO(3))(3) crystal, showing critical dependence on the output coupler used. Polarized laser oscillation with E||x was obtained at 1085.6 nm by using a coupler of 0.5% transmission, yielding an output power of 7.3 W with an optical-to-optical efficiency of 63%. Higher output couplings (>/=2%) led to polarized oscillation with E||z at laser wavelengths 相似文献   

不同组分的钒酸盐混晶Ybt:YxGd1-t-xVO4光谱与激光性质的比较研究

研究了三种掺Yb钒酸盐混晶Yb_0.005:Y_0.298Gd_0.697VO₄, Yb_0.007:Y_0.407Gd_0.586VO₄和Yb_0.009:Y_0.575Gd_0.416VO₄的室温偏振吸收谱和发射谱. 结果表明,最强的吸收和发射相应于π偏振,位 关键词： 掺Yb钒酸盐混晶 吸收谱和发射谱 激光振荡 偏振态     

Persistence of zero velocity fronts in reaction diffusion systems

Steady, nonpropagating, fronts in reaction diffusion systems usually exist only for special sets of control parameters. When varying one control parameter, the front velocity may become zero only at isolated values (where the Maxwell condition is satisfied, for potential systems). The experimental observation of fronts with a zero velocity over a finite interval of parameters, e.g., in catalytic experiments [Barelko et al., Chem. Eng. Sci., 33, 805 (1978)], therefore, seems paradoxical. We show that the velocity dependence on the control parameter may be such that velocity is very small over a finite interval, and much larger outside. This happens in a class of reaction diffusion systems with two components, with the extra assumptions that (i) the two diffusion coefficients are very different, and that (ii) the slowly diffusing variables has two stable states over a control parameter range. The ratio of the two velocity scales vanishes when the smallest diffusion coefficient goes to zero. A complete study of the effect is carried out in a model of catalytic reaction. (c) 2000 American Institute of Physics.     

The power and beauty of electrochemistry

Journal of Solid State Electrochemistry -     

Analysis of the absorption spectrum of 12CD4 between 2180 and 2320 cm−1. Comparative study of ν3 and 2ν3

The high-resolution spectrum of the ν₃ band of ¹²CD₄ has been recorded and analyzed. Corresponding to 367 allowed transitions of this band, 218 lines have been identified between 2180 and 2320 cm^?1. Twelve significant spectral constants have been determined in such a way as to reproduce the spectrum with a standard deviation equal to 7 × 10^?3 cm^?1.A comparative analysis between the present results on ν₃ and those obtained by K. Fox [J. Mol. Spectrosc.9, 381 (1962)] for 2ν₃ showed that the interaction between the two sub-levels E and F₂ of the v₃ = 2 state produces a significant effect of the second order and enabled us to determine the interval between these sublevels, i.e., 20 T₃₃ ～ 30 cm^?1.     

C*-algebras associated with interval maps

For each piecewise monotonic map of , we associate a pair of C*-algebras and and calculate their K-groups. The algebra is an AI-algebra. We characterize when and are simple. In those cases, has a unique trace, and is purely infinite with a unique KMS state. In the case that is Markov, these algebras include the Cuntz-Krieger algebras , and the associated AF-algebras . Other examples for which the K-groups are computed include tent maps, quadratic maps, multimodal maps, interval exchange maps, and -transformations. For the case of interval exchange maps and of -transformations, the C*-algebra coincides with the algebras defined by Putnam and Katayama-Matsumoto-Watatani, respectively.

     

Zeno Product Formula Revisited

We introduce a new product formula which combines an orthogonal projection with a complex function of a non-negative operator. Under certain assumptions on the complex function the strong convergence of the product formula is shown. Under more restrictive assumptions even operator-norm convergence is verified. The mentioned formula can be used to describe Zeno dynamics in the situation when the usual non-decay measurement is replaced by a particular generalized observables in the sense of Davies.