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921.
High-power operation of diode-pumped fiber lasers at wavelength near 2μm are demonstrated with short length of heavily Tm3 -doped silica glass fibers. With 7-cm long fiber, a laser at near 2 μm is obtained with the threshold of 135 mW, maximum output power of 1.09 W, and slope efficiency of 9.6% with respect to the launched power from a laser diode at 790 nm. The output stability of this fiber laser is within 5%.The dependence of the performance of fiber lasers on the operation temperature and cavity configuration parameters is also investigated. 相似文献
922.
923.
A high-repetition-rate eye-safe optical parametric oscillator (OPO), using a non-critically phase-matched KTP crystal intracavity pumped by a passively Q-switched Nd:GdVO4/Cr^4+ :YAG laser, is experimentally demonstrated. The conversion efficiency for the average power is 7% from pump diode input to OPO signal output and the slope efficiency is up to 10.3%. With an incident pump power of 7,3 W, the compact intracavity OPO (IOPO) cavity, operating at 15 kHz, produces an average power of 0.57 W at 1570 nm with a pulse width as short as 6 ns. The peak power at 1570 nm is higher than 6.3 kW. 相似文献
924.
925.
Letn2. The authors establish theL
2(
n
)-boundedness of singular integrals with variable rough Calderón-Zygmund kernels associated to surfaces satisfying some conditions.The research is supported in part by the NNSF and the SEDF of China. 相似文献
926.
The f-depth of an ideal on a module 总被引:2,自引:0,他引:2
Rencai Lü Zhongming Tang 《Proceedings of the American Mathematical Society》2002,130(7):1905-1912
Let be an ideal of a Noetherian local ring and a finitely generated -module. The f-depth of on is the least integer such that the local cohomology module is not Artinian. This paper presents some part of the theory of f-depth including characterizations of f-depth and a relation between f-depth and f-modules.
927.
Tang F Wang J Liu D Yuan G Liu Y Jin Zhu C Fen Zhao Y 《Rapid communications in mass spectrometry : RCM》2002,16(11):1035-1039
The electrospray ionization tandem mass spectrometric (ESI-MS/MS) characteristics and fragmentation mechanisms of eight distamycin analogues containing N-methylpyrrole and N-methylimidazole were investigated. The members of two isomeric groups of distamycin analogues with the same elemental composition can be distinguished by MS/MS spectra of protonated molecules and of significant fragment ions. 相似文献
928.
Akikawa H Ajimura S Chrien RE Eugenio PM Franklin GB Franz J Gang L Imai K Khaustov P May M Pile PH Quinn B Rusek A Sasao J Sawafta RI Schmitt H Tamura H Tang L Tanida K Yuan L Zhou SH Zhu LH Zhu XF 《Physical review letters》2002,88(8):082501
With a germanium detector array (Hyperball), we observed two gamma-ray peaks corresponding to the two transitions (5/2(+)-->1/2(+) and 3/2(+)-->1/2(+)) in the (9)(Lambda)Be hypernucleus which was produced by the 9Be(K-,pi(-)) reaction. The energies of the gamma rays are 3029 +/- 2 +/- 1 keV and 3060 +/- 2 +/- 1 keV. The energy difference was measured to be 31.4(+2.5)(-3.6) keV, which indicates a very small Lambda-spin-dependent spin-orbit force between a Lambda and a nucleon. This is the smallest level splitting by far ever measured in a hypernucleus. 相似文献
929.
Tang L.C. Chang C.C. Chen T.C. Yau H.F. Ye P.X. 《Optical and Quantum Electronics》2002,34(12):1241-1249
We propose a novel geometry for a self-pumped phase conjugator that uses a +c-face incident configuration in a photorefractive pentagon-shaped 0°-cut BaTiO3 crystal for obtaining fast response in phase conjugation. A steady phase-conjugate output with a fast response time 0.4 s is obtained when the incident beam has a 4 W/cm2 intensity. The influences of position and angle on the temporal phase-conjugate response are also investigated. The advantage of this phase conjugator using this novel configuration is improved resolution of a phase-distorted image with a value as high as 128 lp/mm. 相似文献
930.
Molecular motions of polycrystalline cellobiose have been investigated by measuring proton spin–lattice relaxation times, T1 and T1ρ, and the second moment, M2, in both protonated and D2O exchanged forms over the temperature range 120–380 K. T1 relaxation is dominated by the motions of hydroxyl groups between 150 and 380 K, characterised by an activation energy of about 8.74 kJ/mol, whereas T1ρ relaxation is driven by the motions of the same groups between 120 and 300 K. T1ρ results suggest that hydroxyl groups have a distribution of dynamics. Motion of methylene groups was detected in the second-moment experiments at about 350 K, characterised by activation energy of about 40 kJ/mol. Consideration of the calculated and observed rigid-lattice second moments suggests that the reported X-ray data are incorrect for the inter-proton distance on C6′. 13C CPMAS spectra of both protonated and deuterated cellobiose have also been measured. Spectra of the deuterated material showed the existence of a second crystalline form in addition to the normal form. 相似文献