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11.
We demonstrated a stable degenerate synchronously pumped femtosecond optical parametric oscillator (SPOPO) as a divide-by-2 subharmonic generator. The SPOPO exhibited passive all-optical self-phase-locking between the pump and signal/idler and thus required no external electronic feedback to produce the phase-locked subharmonic. We employed a type I phase-matched, 1-mm-long, periodically poled MgO:LiNbO3 crystal as the nonlinear gain element and an 80 MHz mode-locked Ti:sapphire laser with 180 fs pulses tuned at 775 nm as the pump. The SPOPO generated transform-limited 70 fs phase-locked output pulses centered at 1550 nm. The self-phase-locking operation was confirmed by separate beat-note measurement techniques with respect to the pump laser and with respect to an external cw laser. 相似文献
12.
C. Tomas J.P. Girardeau-Montaut M. Afif M. Romand M. Charbonnier T.M. Duc 《Applied Physics A: Materials Science & Processing》1997,64(5):467-471
3+ :YAG laser with 5th harmonic generator, generating 16 ps duration pulses at 213 nm, with energies up to 0.5 mJ. Experimental results concerning
the action of laser pulses, as well as the effects of residual pressure on the cleanliness of the photocathodes surface are
presented and discussed. Influence of laser pulses and residual pressure on the work function of the metal are also investigated.
Received: 15 April 1996/Accepted: 5 November
1996 相似文献
13.
Miroslav Jelinek Tomas Kocourek Josef Zemek Michal Novotný Jaromír Kadlec 《Applied Physics A: Materials Science & Processing》2008,93(3):633-637
Thin SiC
x
films were fabricated by hybrid laser–magnetron deposition system. KrF excimer laser was used for deposition of carbon and
magnetron at the same time for sputtering of Si species. Films were fabricated in argon/hydrogen ambient with and without
additional RF discharge. The substrate temperature was changed up to 700°C. Films topology, crystallinity, composition, chemical
bonds and optical emission spectra were studied. Films were smooth and amorphous. Films of thickness 400–1000 nm were fabricated.
Adhesion moved from 8 to 14 N, depending on deposition conditions. 相似文献
14.
This paper considers Hardy–Lieb–Thirring inequalities for higher order differential operators. A result for general fourth-order
operators on the half-line is developed, and the trace inequality
tr( (-D)2 - CHRd,2\frac1|x|4 - V(x) )-g £ Cgò\mathbbRd V(x)+g+ \fracd4 dx, g 3 1 - \frac d 4,\mathrm{tr}\left( (-\Delta)^2 - C^{\mathrm{HR}}_{d,2}\frac{1}{|x|^4} - V(x) \right)_-^{\gamma}\leq C_\gamma\int\limits_{\mathbb{R}^d} V(x)_+^{\gamma + \frac{d}{4}}\,\mathrm{d}x, \quad \gamma \geq 1 - \frac d 4, 相似文献
15.
16.
Tomas?BerggrenEmail author Maurice?DuitsView authors OrcID profile 《Mathematical Physics, Analysis and Geometry》2017,20(3):19
In this paper we study the asymptotic behavior of mesoscopic fluctuations for the thinned Circular Unitary Ensemble. The effect of thinning is that the eigenvalues start to decorrelate. The decorrelation is stronger on the larger scales than on the smaller scales. We investigate this behavior by studying mesoscopic linear statistics. There are two regimes depending on the scale parameter and the thinning parameter. In one regime we obtain a CLT of a classical type and in the other regime we retrieve the CLT for CUE. The two regimes are separated by a critical line. On the critical line the limiting fluctuations are no longer Gaussian, but described by infinitely divisible laws. We argue that this transition phenomenon is universal by showing that the same transition and their laws appear for fluctuations of the thinned sine process in a growing box. The proofs are based on a Riemann-Hilbert problem for integrable operators. 相似文献
17.
Tomas Fritioff Conny Carlberg Guilhem Douysset Reinhold Schuch Ingmar Bergström 《Hyperfine Interactions》2001,132(1-4):229-242
The Penning trap mass spectrometer SMILETRAP has been considerably improved during the last two years. The helium pressure
has been carefully stabilized and is now independent of irregular air pressure. The temperature of the hyperboloidal precision
trap is stabilized to ±0.03°C. Remaining temperature instabilities are compensated by changes in the current of a warm coil
surrounding the precision trap. The frequency synthesizer is now locked to GPS. This means that it is much easier to accurately
measure resonances during several days. The improvements have demonstrated that in mass doublet measurements with an excitation
time of 1 s it is possible to determine the mass of ions with q/A=1/2 at an uncertainty to a few times of 0.1 ppb, using selected rather than cooled ions. In routine measurements lasting
for one day it is possible to reach a mass uncertainty of 1 ppb. The masses of the following particles and atoms have been
measured with uncertainties in the region 0.3–2 ppb: p, 3H, 3He, 4He, 22Ne, 28Si, 36Ar, 76Ge, 76Se, 86Kr and 133Cs. It has also been shown that though we are using a warm bore the trap pressure is sufficiently low to prevent electron
capture from the rest gas for excitation times of 3 s and for ion charges as high as 50+.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
Aleksandar Donev Vasily V. Bulatov Tomas Oppelstrup George H. Gilmer Babak Sadigh Malvin H. Kalos 《Journal of computational physics》2010,229(9):3214-3236
We develop an asynchronous event-driven First-Passage Kinetic Monte Carlo (FPKMC) algorithm for continuous time and space systems involving multiple diffusing and reacting species of spherical particles in two and three dimensions. The FPKMC algorithm presented here is based on the method introduced in Oppelstrup et al. [10] and is implemented in a robust and flexible framework. Unlike standard KMC algorithms such as the n-fold algorithm, FPKMC is most efficient at low densities where it replaces the many small hops needed for reactants to find each other with large first-passage hops sampled from exact time-dependent Green’s functions, without sacrificing accuracy. We describe in detail the key components of the algorithm, including the event-loop and the sampling of first-passage probability distributions, and demonstrate the accuracy of the new method. We apply the FPKMC algorithm to the challenging problem of simulation of long-term irradiation of metals, relevant to the performance and aging of nuclear materials in current and future nuclear power plants. The problem of radiation damage spans many decades of time-scales, from picosecond spikes caused by primary cascades, to years of slow damage annealing and microstructure evolution. Our implementation of the FPKMC algorithm has been able to simulate the irradiation of a metal sample for durations that are orders of magnitude longer than any previous simulations using the standard Object KMC or more recent asynchronous algorithms. 相似文献
19.
G. S. Shakurov R. I. Khaibullin V. G. Tomas D. A. Fursenko R. I. Mashkovtsev O. N. Lopatin A. G. Nikolaev B. P. Gorshunov E. S. Zhukova 《Physics of the Solid State》2017,59(8):1600-1606
Electron spin resonance spectra of non-Kramers bivalent iron (Fe2+) ions have been detected in synthetic and natural beryl crystals with an iron impurity. The observed ESR spectra have been attributed to resonance transitions of Fe2+ ions from the ground (singlet) state to excited (doublet) levels with the splitting Δ = 12.7 cm–1 between the levels. The experimental angular and frequency dependences of the resonance field of the ESR signal have been described by the spin Hamiltonian with the effective spin S = 1. The analysis of the ESR data and optical absorption spectra indicates that the Fe2+ ions are situated in tetrahedral positions and substitute Be2+ cations in the beryl structure. 相似文献
20.
Svensson T Andersson M Rippe L Johansson J Folestad S Andersson-Engels S 《Optics letters》2008,33(1):80-82
We present minimalistic and cost-efficient instrumentation employing tunable diode laser gas spectroscopy for the characterization of porous and highly scattering solids. The sensitivity reaches 3 x 10(-6) (absorption fraction), and the improvement with respect to previous work in this field is a factor of 10. We also provide the first characterization of the interference phenomenon encountered in high-resolution spectroscopy of turbid samples. Revealing that severe optical interference originates from the samples, we discuss important implications for system design. In addition, we introduce tracking coils and sample rotation as new and efficient tools for interference suppression. The great value of the approach is illustrated in an application addressing structural properties of pharmaceutical materials. 相似文献
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