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111.
Liangshun Han Song Liang Can Zhang Liqiang Yu Lingjuan Zhao Hongliang Zhu Baojun Wang Chen Ji Wei Wang 《中国光学快报(英文版)》2014,12(9):91402-44
We report the fabrication of widely tunable ridge waveguide distributed Bragg reflector(DBR) lasers with InGaAsP butt-joint as grating material. The shape of the butt–joint interface is found to have significant effect on the properties of the lasers. It is shown that irregular mode jumps during wavelength tuning can be avoided by a V-shaped butt–joint interface. From the fabricated device, 23 channels with 0.8 nm spacing and greater than 35 dB side mode suppression ratios are obtained. The different tuning characteristics of the ridge waveguide and the previously reported buried ridge stripe DBR lasers are discussed. Combined with the wide tuning range and the simple structure, the ridge waveguide DBR lasers are promising for use in wavelength division multiplexing passive optical networks(WDM-PONs). 相似文献
112.
Xiujing Han 《Physics letters. A》2009,373(40):3643-3649
By employing a special feedback controlling scheme, a hyperchaotic Lorenz system with the structure of two time scales is constructed. Two kinds of bursting phenomena, symmetric fold/fold bursting and symmetric sub-Hopf/sub-Hopf bursting, can be observed in this system. Their respective dynamical behaviors are investigated by means of slow-fast analysis. In particular, symmetric fold/fold bursting is of focus-focus type, namely, both the up-state and the down-state are stable focus, which is different from the usual fold/fold bursting; Symmetric sub-Hopf/sub-Hopf bursting is also of focus-focus type, which has not been reported in previous work. Furthermore, phase plane analysis has been introduced to explore the evolution details of the fast subsystem for symmetric sub-Hopf/sub-Hopf bursting. With the variation of the parameter, symmetric sub-Hopf/sub-Hopf bursting can evolve to symmetric chaotic bursting or even hyperchaos. 相似文献
113.
Ning Tang Bo Shen Kui Han Xiao-Wei He Chun-Ming Yin Zhi-Jian Yang Zhi-Xin Qin Guo-Yi Zhang Tie Lin Wen-Zheng Zhou Li-Yan Shang Jun-Hao Chu 《Applied Physics A: Materials Science & Processing》2009,96(4):953-957
The subband structure and occupation in the triangular quantum well at Al
x
Ga1−x
N/GaN heterointerfaces have been investigated by means of temperature dependent Shubnikov–de Haas (SdH) measurements at low
temperatures and high magnetic fields under illumination. After the illumination of the heterostructures, the total two-dimensional
electron gas concentration increases, and the SdH oscillation amplitudes are enhanced when there is no additional subband
occupation. It is also found that the energy separation between the subbands decreases after the illumination. We suggest
that the illumination decreases the electric field and thus weakens the quantum confinement of the triangular quantum well
at Al
x
Ga1−x
N/GaN heterointerfaces. The GaN layer is thought to be the primary contributor of the excited electrons by the illumination. 相似文献
114.
Residual microstructures associated with hypervelocity impact craters in 55 vol.% TiB(2)/2024Al composite were investigated by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). TiB(2)-Al interface, TiB(2) particles and Al matrix before and after hypervelocity impact were compared to discuss the effect of hypervelocity impact. A new Al(x)O(1-x) phase with the fcc structure and the crystal parameter of 0.69 nm was formed at TiB(2)-Al interface. Stacking fault with width of 10-20 nm was formed along the (001) plane of TiB(2) particle. Formation of nanograins (≈ 100 nm) was observed within Al matrix, moreover, lamellar S' phase was transformed into lenticular or spherical S phase after hypervelocity impact. 相似文献
115.
Yong Zhang Yun-Hai Jia Jin-Wen Chen Xue-Jing Shen Lei Zhao Chun Yang Yong-Yan Chen Yong-Hui Zhang Peng-Cheng Han 《Frontiers of Physics》2012,7(6):714-720
Lens-to-sample distances, delay time, atmospheric condition, laser pulse energy, etc. had obvious effects on the analytical performance of laser-induced breakdown spectroscopy. In this paper, these parameters are investigated in greater detail and we will explain how they have influences on the analytical performance. The results show that the focal plane under the sample surface can improve precision and detection limit, and the delay time should be decided according to sensitivity and accuracy. Spectral line intensity is stronger in argon than helium, nitrogen and air gas environment. Pulse energy should exceed energy threshold (about 50 mJ) which can generate plasma, and the energy should not exceed about 300 mJ to avoid plasma shielding. Under optimum parameters, concentration relative standard deviation of C, Si, Mn, P, S, Ni, and Cr for low-alloyed steel (sample number 11278) which were measured 11 times is 2.37%, 2.18%, 2.23%, 7.8%, 9.34%, 1.92%, and 2.13%, respectively. And the detection limit of C, Si, Mn, P, S, Ni, and Cr for pure steel is 0.0045%, 0.0072%, 0.0069%, 0.0027%, 0.0024%, 0.0047%, and 0.0024%, respectively. 相似文献
116.
We prove that the supergravity r- and c-maps preserve completeness. As a consequence, any component \({\mathcal{H}}\) of a hypersurface {h = 1} defined by a homogeneous cubic polynomial h such that \({-\partial^2h}\) is a complete Riemannian metric on \({\mathcal{H}}\) defines a complete projective special Kähler manifold and any complete projective special Kähler manifold defines a complete quaternionic Kähler manifold of negative scalar curvature. We classify all complete quaternionic Kähler manifolds of dimension less or equal to 12 which are obtained in this way and describe some complete examples in 16 dimensions. 相似文献
117.
Efficient laser operation is demonstrated at room temperature with a new Yb:Lu3Ga5O12 garnet crystal. A continuous-wave output power of 5.36 W is generated at a center oscillation wavelength of 1041 nm, with an optical-to-optical efficiency of 51% and the slope efficiency of 63%. In passively Q-switched operation, the maximum average output power reaches 4.0 W (center wavelength of 1034 nm) at a repetition rate of 71 kHz, with optical-to-optical and slope efficiencies measured to be 40% and 50%, respectively. Laser pulses of 26 ns duration are generated with a pulse energy of 91 μJ and peak power of 3.5 kW. 相似文献
118.
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