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Influence of Channel Power and Pumping Configuration on the Gain Profile of Distributed Raman Fiber Amplifier
XIN Xiang-Jun, YU Chong-Xiu, ZHANG Ru, REN Jian-Hua, LI An-Jian, WU Qiang, XIN Yu, WANG Chuan-Lin, ZHENG Wen-Xiao, RUAN Shuang-Chen, DU Ge-Guo, XIN Gang, YANG Xiao-Qiang
Chin. Phys. Lett. 2003, 20 (2):
237-239
.
The influence of channel power and pumping configuration on the gain profile of a distributed Raman fiber amplifier has been experimentally measured. The experimental results show that the influence is significant and should be considered during the gain flatness optimization of the distributed Raman fiber amplifier.
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Photo-Induced Magnetic Anisotropy of Polymer Film Containing Azobenzene Organic Free Radical Group
XU Ze-Da, ZHANG Yong, CHEN Xiao-Fang, FAN Xing-He, WAN Xin-Hua, ZHOU Qi-Feng
Chin. Phys. Lett. 2003, 20 (2):
240-242
.
The forward degenerate four-wave mixing geometry was employed to induce microstructure in an organic free radical azobenzene polymer film. Before irradiated with Ar+ laser beams (λ =514.5 nm), the azobenzene organic free radical polymer exhibits magnetic isotropic measured by superconducting quantum interference device. After photo-induced microstructure, the polymer film becomes magnetic anisotropy. When the applied magnetic field H = 50 Gauss, the magnetization along the normal direction of the polymer film is Mz = 5.5 x 10-5 emu/g, which is larger than Mx = 4.1 x 10-5 emu/g in the direction parallel to the polymer film.
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Some Invariants of the Silk Quasi-lattices
LUAN Chang-Fu
Chin. Phys. Lett. 2003, 20 (2):
267-268
.
Based on the spectral structure of a class of one-dimensional three-tile quasiperiodic lattice models that are established in 1990 for which the (concurrent) substitution rules are S → M, M → L, and L → LS, with S, M, and L representing the short, medium, and long tiles of atomic spacings, respectively, we suggest that S is E (egg), M is SI (silkworm) and L is M (moth), for easily understanding. By the use of the number theory, we have rigorously proven the existence of the limit θ = limn → ∞ Sn-1/Sn ≈ 0.68232789 ..., where Sn is the number of elements contained in the n-th silk sequence. Some relations among the sequences En, SIn, and Mn are found, where the subscript n means the n-th generation.
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Self-Diffusion Mechanisms of Adatom on Al (001), (011) and (111) Surfaces
SUN Yu-Jie, LI Jia-Ming,
Chin. Phys. Lett. 2003, 20 (2):
269-272
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Using the first-principle molecular dynamical calculations, we have studied the adatom self-diffusion mechanisms on fcc Al (001), (011) and (111) surfaces. On each surface, there are several mechanisms, among which there is one favour mechanism with the minimum barrier energy. The atomic exchange mechanism along the [100] direction on the (001) surface, the long bridge hopping mechanism along the [ī10] direction on the (011) surface, and the bridge hopping mechanism along the [112] direction on the (111) surface are the favour mechanisms. The activation energy profiles for various self-diffusion mechanisms are studied in details.
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Microstructural and Electrical Properties of ZrO2 Thin Films Prepared on Silicon on Insulator with Thin Top Silicon
ZHANG Ning-Lin, SONG Zhi-Tang, SHEN Qin-Wo, LIN Cheng-Lu
Chin. Phys. Lett. 2003, 20 (2):
273-276
.
Amorphous zirconia thin films were deposited directly on silicon-on-insulator (SOI) substrates with thin top silicon by ultra-high vacuum electron beam evaporation. Spreading resistance profile and scanning transmission-electron microscopy (TEM) were used to detect the interface quality and microstructure, revealing that the interface between the zirconium oxide films and top silicon was abrupt and clear. The films kept to be amorphous up to the rapid thermal temperature of 700°C for 300 s, but arriving at 700°C an unknown interfacial product appeared, which was probably ZrSixOy. High frequency capacitance-voltage (C-V) characteristics at 1 MHz performed on metal-oxide-SOI structure revealed that this interfacial product exhibited good electrical properties of zirconia thin films. When the annealing temperature increased from 600°C to 700°C, flat voltage VFB changed from -2.451 to -1.741 eV, showing the improvement in the quality of the films. The cumulative region capacitance decreased from 3.058 x 10-11F to 3.012 x 10-11F, indicating the increase of equivalent oxide thickness, which is in agreement with the result of high-resolution cross-sectional TEM.
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Magnetic Exchange-Coupled Sm(Co,R)/Cr (R = Al, Si, Ti, Nb, Cu) Series Films for Ultrahigh-Density Longitudinal Recording Media
WANG Xiang, LI Zuo-Yi, LI Zhen, CAI Chang-Bo, HUANG Zhi-Xin, LIAO Hong-Wei, WANG Hao-Min, LIN Geng-Qi
Chin. Phys. Lett. 2003, 20 (2):
281-283
.
SmCoR (R=Al,Si,Ti,Nb,Cu)/Cr series films were fabricated as one kind of promising materials for the ultrahigh density longitudinal magnetic recording media. The Sm(Co,Al,Si)/Cr thin films with coercivity up to 2.36 kOe, squareness ratio S near 0.94 and coercive squareness ratio S* about 0.9 were obtained. The Cr interlayer caused magnetic decoupling in Sm(Co,Al,Si)/Cr/Sm(Co,Al,Si) thin films. High coercivity of 3400--3840\,Oe and extremely fine grain size of 5-8 nm for the magnetic layer were examined. Using different substrate bias among the Sm(Co,Al,Si)(deposited with substrate bias of -150 V)/Sm(Co,Al,Si)(deposited with no substrate bias)/Sm(Co,Al,Si)(deposited with substrate bias of -150 V), the multilayer exhibited high coercivity of 2960 Oe and S* of 0.96. Sm(Co,Al,Si)/Sm(Co,Ti,Cu)/Sm(Co,Nb,Cu) trilayer improved matching between the magnetic layer and the Cr underlayer, and led to increasing in-plane anisotropy, high coercivity of 3280 Oe and S* of 0.92. Lattice matching of SmCoR {1121} and Cr {110}, etc. were found under various conditions. The microstructures of these four kinds of medium were also examined. The results suggest that it is possible to produce Sm (Co,Al,Si,Ti,Nb,Cu) multi-layer media with the combined magnetic properties required for the ultrahigh density magnetic recording.
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Electroluminescence and Photoluminescence from Scored Si-Rich SiO2 Film/p-Si Structure
RAN Guang-Zhao, SUN Yong-Ke, CHEN Yuan, DAI Lun, CUI Xiao-Ming, ZHANG Bo-Rui, QIAO Yong-Ping, MA Zhen-Chang, ZONG Wan-Hua, QIN Guo-Gang,
Chin. Phys. Lett. 2003, 20 (2):
298-300
.
Electroluminescence (EL) is observed from the Au/Si-rich SiO2 film/p-Si diodes, in which the Si-rich SiO2 films are scored purposely by a diamond tip. The EL intensity of the scored diode annealed at 800°C is about 6 times of that of the unscored counterpart. The EL spectrum of the unscored diode could be decomposed into two Gaussian luminescence bands with peaks at about 1.83 and 2.23 eV, while for the EL spectrum of the scored diode, an additional Gaussian band at about 3.0 eV appears, and the 1.83-eV peak increases significantly in intensity. The photoluminescence (PL) spectrum of an unscored Si-rich SiO2 film has only one band peaking at about 1.48 eV, whereas the PL spectrum of the scored one has two bands at about 1.48 and 1.97 eV. We consider that the high-density defect regions produced by the scoring provide new luminescence centers and become some types of nonradiative centers in the Si oxide layer, which thus result in changes of the EL and PL spectra.
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Direct, etching of GaAs Crystal Excited by a Vacuum Ultraviolet Lamp
HAN Zheng-Fu, LIAO Yan-Lin, ZHOU Hong-Jun, JIANG Zuo-Hong, ZHANG Guo-Bin, CAO Zhuo-Liang,
Chin. Phys. Lett. 2003, 20 (2):
308-310
.
A successful direct, etching system excited by a vacuum ultraviolet hollow cathode lamp is reported. The result shows that the facility can transfer a mesh pattern exactly and directly to n-type GaAs wafer, which is the same as that direct etched by synchrotron radiation.
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43 articles
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