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41.
42.
We have demonstrated high-energy quasi-phase-matched optical parametric oscillation in a 3-mm-thick periodically poled 5-mol. % MgO-doped LiNbO3 device with a 32.1-microm grating period and a 30-mm length. With a large-spot-size pump laser of 2.2-mm diameter, we obtained a total output pulse energy of 22 mJ for both the signal (wavelength 1.82 microm) and the idler (2.56 microm) waves at an input pump energy of 46 mJ. 相似文献
43.
Highly efficient 1-microm continuous-wave laser emission in 3-mm-thick, 0.5- and 1.0-at. % Nd:GdVO4 crystals longitudinally pumped at 879 nm into the laser emitting level is reported. Under Ti:sapphire pumping, the slope efficiency in absorbed power is approximately 80% for both crystals, while the slope efficiency, the optical-to-optical efficiency (at 1700-mW pump power), and the laser threshold in incident power are 79%, 78%, and 31 mW for 0.5-at. % Nd and 80%, 77%, and 40 mW for 1.0-at. % Nd, respectively. The slope efficiency is close to the quantum defect limit, the difference being fully accounted for by the residual optical losses. Under 879-nm diode laser pumping, the slope efficiency and the optical-to-optical efficiency in absorbed power of the 0.5-at. % Nd:GdVO4 crystal are 60% and 53%, owing to poorer superposition of the pumped and the laser mode volumes. 相似文献
44.
Ashihara S Shimura T Kuroda K Yu NE Kurimura S Kitamura K Ro JH Cha M Taira T 《Optics letters》2003,28(16):1442-1444
Large nonlinear phase shifts were generated with femtosecond pulses at 1560 nm through cascaded quadratic interactions in periodically poled MgO-doped LiNbO3. The off-diagonal component of the nonlinear coefficient was utilized for simultaneous quasi phase matching and group-velocity matching. The effective nonlinear refractive index was varied from -2.9 x 10(-14) to +3.3 x 10(-14) cm2/W by tuning the phase-mismatch conditions. 相似文献
45.
Imamura H Shimizu A Sato H Sugimoto Y Sakuraba S Yamada K Morishima H 《Chemical & pharmaceutical bulletin》2001,49(4):476-479
An effective and practical procedure for the synthesis of J-111,225 (1), a new 1beta-methylcarbapenem, was developed using 4-mercapto-2-14-(N-methylaminomethyl)phenyl]pyrrolidine (2a) as a precursor. The coupling reaction of 2a with p-nitrobenzyl (PNB)-protected 1beta-methylcarbapenem enolphosphate 3a and successive removal of PNB group afforded J-111,225 (1) in significantly increased yield compared to the ordinary procedure using a C-2 side-chain thiol with amino-protective groups. 相似文献
46.
We theoretically study the electron transport through a magnetic point contact (PC) with special attention given to the effect of an atomic scale domain wall (DW). The spin precession of a conduction electron is forbidden in such an atomic scale DW and the sequence of quantized conductances depends on the relative orientation of magnetizations between left and right electrodes. The magnetoresistance is strongly enhanced for the narrow PC and oscillates with the conductance. 相似文献
47.
A. Tanaka R. Saito T. Kamikake M. Imamura H. Yasuda 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):229-232
We have performed the optical and photoelectron
spectroscopic studies of alkyl-passivated Si nanoparticles synthesized by a
solution route. The alkyl-passivated Si nanoparticle with mean diameter less
than about 2 nm exhibits a strong ultraviolet-blue photoluminescence.
Furthermore, we have directly investigated their electronic structures in
the vicinity of Fermi level by means of valence-band photoemission
measurements using synchrotron radiation. From these results, the detailed
optical properties and electronic structures of alkyl-passivated Si
nanoparticles are discussed. 相似文献
48.
The one-dimensional totally asymmetric simple exclusion process (TASEP) is considered. We study the time evolution property
of a tagged particle in the TASEP with the step initial condition. Calculated is the multi-time joint distribution function
of its position. Using the relation of the dynamics of the TASEP to the Schur process, we show that the function is represented
as the Fredholm determinant. We also study the scaling limit. The universality of the largest eigenvalue in the random matrix
theory is realized in the limit. When the hopping rates of all particles are the same, it is found that the joint distribution
function converges to that of the Airy process after the time at which the particle begins to move. On the other hand, when
there are several particles with small hopping rate in front of a tagged particle, the limiting process changes at a certain
time from the Airy process to the process of the largest eigenvalue in the Hermitian multi-matrix model with external sources. 相似文献
49.
50.
The intramolecular Pauson–Khand cyclization in the presence of both aniline and nitrobenzene was used to improve the construction of N-nitrobenzenesulfonyl-protected 3-azabicyclo[4.3.0]nonane skeletons. We found that aniline enhanced the cyclization and that nitrobenzene prevents the concurrent reduction in this process. This combination of mediators allows for the efficient synthesis of bioactive azabicyclic nonane-type alkaloids and the use of milder deprotection conditions in the synthetic route. 相似文献