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991.
We predict that employing a Bragg grating to simultaneously phase match and induce large temporal walk-off between the signal and slow propagating pump in a nonlinear crystal can be conducive to development of passively mode locked optical parametric oscillators in which cw near-infrared pump is efficiently converted into short middle-infrared pulses. 相似文献
992.
Gishamol Mathew Anju Babu Jesly Jacob Vincent Mathew 《Superlattices and Microstructures》2008,44(2):203-207
This paper discusses the magneto-optic phase shift in garnet/semiconductor-on-insulator plasmonic waveguides. We consider two structures: (1) Y IG/Si/SiO2 and (2) Y IG/GaInAsP/AlInAs-oxide. A dispersion relation for the plasmon propagation has been derived and the nonreciprocal phase shift of the fundamental TM mode has been determined at wavelengths of 1.55 μm, 1.5 μm and 1.3 μm. 相似文献
993.
994.
Supported in part by NSA grant MDA904-89-H-2038, PSC-CUNY grant 662330, and the Center for Discrete Mathematics and Theoretical Computer Science (DIMACS), a National Science Foundation Science and Technology Center under NSF grant STC88-09648. 相似文献
995.
A simple method for the purification of fluorine gas is described. With the exception of nitrogen and argon, all impurities usually present in commercial fluorine can be readily removed by 1) conversion of O2 to non-volatile O+2 salts, and 2) a 70 to 63°K trap-to-trap distillation. 相似文献
996.
In this paper we prove Gårding's inequality for linear differential operators in generalized divergence form which satisfy a generalized Ehrling inequality, an ellipticity condition and a condition on the coefficients. Using a compact imbedding between certain anisotropic Sobolev spaces we substitute the first condition (Ehrling's inequality) by a simple condition on a set of multi-indices. 相似文献
997.
We report the variation of the thermal diffusivity in the high temperature superconductor YBa2Cu3O7−δ below the transition temperature measured using photo-acoustic technique α is found to increase sharply belowT
c. Qualitative explanations are given. 相似文献
998.
We study the free energy of continuous spin-systems on Z
d
, in the framework of Laplace integrals and transfer operators. Under a weak coupling condition, we show that the free energy in the low-temperature limit is determined, up to an exponentially small error, by the restriction to a neighbourhood of global minima of the energy. We have results for some single- and double-well problems. 相似文献
999.
Reversed phase ion pair chromatography is a highly selective separation technique for the determination of free porphyrin carboxylic acids from human materials. Isocratic and gradient elution methods can be used to analyse porphyrin isomers and to establish porphyrin profiles for the biochemical diagnosis of porphyrias. Ion pair high performance liquid chromatography led to the discovery of the atypical isomers II and IV of uroporphyrin and coproporphyrin in human urine. Advantages and limitations of the ion pair technique are discussed. 相似文献
1000.
The glass transition in Ge
x
Se1−x
) (0·1 ⩽x ⩽ 0·25) glasses has been investigated using the photoacoustic (PA) technique. It is found that the PA amplitude and phase
undergo anomalous changes at the glass transition temperatureT
g. The amplitude has critical minimum and phase has maximum values atT
g. The variation of the thermal diffusivity, determined by measuring the frequency dependence of the PA amplitude and phase,
with temperature shows sharp decrease near the glass transition temperature. The temperature dependence of the optical energy
gap also has been measured and it shows a decrease with temperature for all compositions, the rate of decrease being higher
for temperatures greater thanT
g. 相似文献