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991.
992.
提出并利用高频CO2激光脉冲在普通单模通信光纤上写出了包层旋转折变型长周期光纤光栅(R-LPFG). 在分析R-LPFG波导结构和双折射特性的基础上,对光栅周期数和折变旋转度分别为50和7.2°/周期的R-LPFG进行了实验研究.结果表明,这种类型的光栅可极大地降低其谐振波长对横向负荷不同作用方向所表现出的方向相关性,并且其谐振峰幅度横向负荷灵敏度在任意方向下均高达0.37dB/(g·mm-1) ,是普通LPFG横向负荷灵敏度的9倍左右.利用R-LPFG的温度线性响应特性和独特的横向负荷特性,设计并实验研究了一种动态增益均衡器,用其平坦掺铒光纤放大器增益谱,在C波段32nm范围内,其平坦度小于±0.5dB,可满足实际环境对通信系统的平坦应用要求.
关键词:
光纤通信技术
长周期光纤光栅
动态增益均衡
旋转折变 相似文献
993.
994.
应用特征矩阵法研究了非均匀渐变界面Al0.9Ga0.1As/AlyGa1-yAs/GaAs/AlxGa1-xAs DBR的光学特性.建立了非均匀渐变界面AlyGa1-yAs的折射率模型,并得到了渐变界面特征矩阵的解析解,通过特征矩阵法分别计算了突变GaAs/Al0.9Ga0.1As DBR和渐变DBR的反射谱和反射相移,分析了非均匀渐变层对DBR光学特性的影响,对渐变DBR,需要在DBR前面再增加一定厚度的非均匀渐变相位匹配层才能使整个DBR满足中心波长相位匹配条件,并通过光学厚度近似方法求出相位匹配层厚度.
关键词:
DBR
反射谱
反射相移
特征矩阵法 相似文献
995.
996.
997.
998.
F. Pereira Dos Santos J. Léonard Junmin Wang C. J. Barrelet F. Perales E. Rasel C. S. Unnikrishnan M. Leduc C. Cohen-Tannoudji 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(1):103-109
We recently observed a Bose-Einstein condensate in a dilute gas of 4He in the 23S1 metastable state. In this article, we describe the successive experimental steps which led to the Bose-Einstein transition
at 4.7 μK: loading of a large number of atoms in a MOT, efficient transfer into a magnetic Ioffé-Pritchard trap, and optimization
of the evaporative cooling ramp. Quantitative measurements are also given for the rates of elastic and inelastic collisions,
both above and below the transition.
Received 15 October 2001 相似文献
999.
AFM study of gold nanowire array electrodeposited within anodic aluminum oxide template 总被引:7,自引:0,他引:7
Uniform gold nanowires were synthesized by electrodepositing the gold under a very low ac frequency in the pores of an anodic
aluminum oxide (AAO) template. The surface of the Au/AAO composite is very even and appeared purplish red. Atomic force microscopy
observation indicates that the template membranes we obtained have hexagonally close-packed nanochannels. The gold nanowire
array is very orderly arranged after partially dissolving the aluminum oxide membrane. Gold nanowires were also characterized
by transmission electron microscopy and the phase structure of the Au/AAO composite was proved by X-ray diffraction.
Received: 19 April 2001 / Accepted: 28 April 2001 / Published online: 27 June 2001 相似文献
1000.
Wang X. Yang S. Wang J. Li M. Jiang X. Du G. Liu X. Chang R.P.H. 《Optical and Quantum Electronics》2002,34(9):883-891
High quality ZnO film was deposited by plasma-assisted metal-organic chemical vapor deposition (MOCVD). We observed a dominant peak at 34.6° due to (0 0 2) ZnO, which indicated that the growth of ZnO film was strongly C-oriented. The full-width at half-maximum (FWHM) of the -rocking curve was 0.56° indicating relatively small mosaicity. Photoluminescence (PL) measurement was performed at both room temperature and low temperature. Ultraviolet (UV) emission at 3.30 eV was found with high intensity at room temperature while the deep level transition was weakly observed at 2.513 eV. The ratio of the intensity of UV emission to that of deep level emission was as high as 193, which implied high quality of ZnO film. From PL spectrum at 10 K, we observed A-exciton emission at 3.377 eV and D°X bound exciton transition at 3.370 eV. The donor–acceptor transition and LO phonon replicas were observed at 3.333 and 3.241 eV respectively. Raman scattering was performed in back scattering at room temperature. The E2, A1(LO) and A1(TO) mode was seen at 437.6, 575.8 and 380 cm–1 respectively. In comparison with Raman spectrum of ZnO powder, we found that ZnO film was nearly free of strain, which indicated high crystal quality. 相似文献