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901.
A Q-switched mode-locking femtosecond all-fiber laser based on a 2 cm long homemade Er3+/Yb3+ codoped phosphate glass fiber has been reported. By using the nonlinear polarization evolution technique, a nearly 100% modulation
depth of mode-locking pulse train is achieved. At a pump power of 410 mW, the energy of each Q-switched envelope, whose width
is about 220 μs, is 10 μJ, while the duration of mode-locking pulse within the Q-switched envelope is 318-fs. 相似文献
902.
X. F. Yang D. Y. Shen T. Zhao H. Chen J. Zhou J. Li H. M. Kou Y. B. Pan 《Laser Physics》2011,21(6):1013-1016
We report on a high power polycrystalline Er:YAG ceramic laser in-band pumped by a cladding-pumped Er, Yb fiber laser wavelength
locked at 1532 nm with a volume Bragg grating. Using 1.0 at % Er3+-doped ceramic as the gain medium and an output coupler of 10% transmission, the laser had a threshold pump power of ∼1.5
W and generated 11 W of continuous-wave output at 1645 nm for 23.3 W of incident pump power at 1532 nm, corresponding to a
slope efficiency with respect to incident pump power of 51%. 相似文献
903.
904.
A passively Q-switched waveguide laser, to our knowledge, has been firstly demonstrated in Nd: YVO4 crystal formed by 3 MeV Si+ ion implantation at a dose of 1 × 1015 ions/cm2 at room temperature, in which GaAs was used as saturable absorber. The dependences of the average output power, pulse width,
pulse repetition rate on absorbed pump power have been measured at different output plane mirror transmissions. At an absorbed
pump power of 78.8 mW and output transmission of 20%, the shortest pulse width of 3.88 ns was obtained, corresponding to the
peak power and single pulse energy of 212 W and 0.82 μJ, respectively. The threshold pump power was as low as 40 mW, and the
slope efficiency was about 64.5% when the absorbed pump power was lower than 70 mW. 相似文献
905.
Ma Mo Yang Liwen Ren Guozhong Xu Changfu Lin Jianguo Yang Qibin 《Journal of luminescence》2011,131(7):1482-1486
Lanthanide (Ln3+) doped BaYF5 (Ln=Yb3+, Er3+, Tm3+) nanocrystals (NCs) with a mean size of approximately 10 nm are synthesized by a solvothermal method using oleic acid as a stabilizing agent at 210 °C. The size of BaYF5 NCs can be controlled by simply tuning the reaction parameters such as reaction temperature, reaction time and the molar ratio of F−/Y3+. The detailed structure investigation reveals that the as-synthesized BaYF5 NCs are in the cubic structure with space group Fm3¯m instead of the reported tetragonal structure. Ln3+ cations occupy crystal lattice positions with lower point symmetry, which may lead to high upconversion efficiency under the excitation of a 980 nm diode laser. By adjusting the dopant concentrations of Yb3+, Er3+ and Tm3+, intense near-infrared, blue, yellow and white upconversion emissions are readily realized, respectively. The desirable property of the ultrasmall monodisperse NCs makes it the promising material for the applications in miniaturized solid-state light sources, multicolor three-dimensional display devices and fluorescent labels for biomedicine imaging. 相似文献
906.
Diange Yang 《Journal of sound and vibration》2011,330(11):2457-2469
In this paper, a new acoustic video camera system is developed and its calibration method is established. This system is built based on binocular vision and acoustical holography technology. With binocular vision method, the spatial distance between the microphone array and the moving vehicles is obtained, and the sound reconstruction plane can be established closely to the moving vehicle surface automatically. Then the sound video is regenerated closely to the moving vehicles accurately by acoustic holography method. With this system, the moving and stationary sound sources are treated differently and automatically, which makes the sound visualization of moving vehicles much quicker, more intuitively, and accurately. To verify this system, experiments for a stationary speaker and a non-stationary speaker are carried out. Further verification experiments for outdoor moving vehicle are also conducted. Successful video visualization results not only confirm the validity of the system but also suggest that this system can be a potential useful tool in vehicle's noise identification because it allows the users to find out the noise sources by the videos easily. We believe the newly developed system will be of great potential in moving vehicles' noise identification and control. 相似文献
907.
Jicheng Wang Yueke Wang Xueru Zhang Kun Yang Yuxiao Wang Shutian Liu Yinglin Song 《Optik》2011,122(20):1808-1810
A transmission line model for subwavelength metallic grating with single cut is presented. The model is based on analogy between the subwavelength metallic structure and the microwave transmission line theory. The analytical expression for the transmission is derived by the transfer matrix method. To confirm our model, the finite-difference time-domain (FDTD) method simulations are carried out. The influences of the position of the cuts on the higher modes of slit are presented. It is found that the transmission line model gives analytical prediction about the evolution of the transmission spectra. 相似文献
908.
Schottky-barrier ultraviolet (UV) detectors based on ZnO-nanowires (NWs) were fabricated with Pt as electrodes in this investigation. The ZnO NWs synthesized by the hydrothermal method were characterized by field-emission scanning electron microscopy (FE-SEM), Raman and PL spectroscopy. Photoelectric properties under 254 and 365 nm UV light were investigated. It is found that the photo-response properties of the devices under 365 nm UV light are better than those under 254 nm UV light, which is further illustrated by light transmission theory, energy-band diagram and absorption spectra. The results demonstrate that ZnO NWs detectors with selectivity to near-UV (NUV) light are promising candidates in photoelectric devices. 相似文献
909.
910.
基于磁荷模型,在有限差分法基础上,推导了3维永磁体数值算法,结合全3维PIC/MCC粒子模拟算法,数值分析比较了外置型和“伞状”型两种特殊形态多峰磁场对电子能量沉积的影响。模拟结果表明:二者都能对粒子起到约束作用且能过滤引出负氢离子,同时二者电子能量分布规律基本一致,都呈现了双电子能态,符合等离子体放电基本机理;外置型过滤磁场对粒子的约束能力更强,能明显产生更多的粒子,总粒子数大约是“伞状”型过滤磁场情况下的4倍;“伞状”型过滤磁场能有效地抑制由磁场不均匀所引起的电子漂移,使产生的负氢离子空间分布更均匀。模拟结果与国外实验结果基本一致。 相似文献