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111.
报告了一种新的长焦距光学系统杂光系数测量装置,该装置除具有避免了制作大直径积分球的优点外,还能精确测量轴外杂光系数,分析各部分杂光源对杂光系数的影响. 相似文献
112.
113.
We design and demonstrate an all-optical temporal differentiator based on a simple Moir fiber grating operated in reflection. The simulation results prove that a single Moir fiber grating with only one π-phase shifted point can act as the first-order temporal differentiator and that a Moir fiber grating incorporating two symmetrical π-phase shifted points can act as the second-order temporal differentiator. A practical Moir fiber grating is fabricated, thereby proving that such a grating can act as the first-order temporal differentiator. Our results verify the feasibility, flexibility, and accuracy of the proposed method. 相似文献
114.
Pan Zhang 《Journal of statistical physics》2012,148(3):502-512
Based on dynamical cavity method, we propose an approach to the inference of kinetic Ising model, which asks to reconstruct couplings and external fields from given time-dependent output of original system. Our approach gives an exact result on tree graphs and a good approximation on sparse graphs, it can be seen as an extension of Belief Propagation inference of static Ising model to kinetic Ising model. While existing mean field methods to the kinetic Ising inference e.g., naïve mean-field, TAP equation and simply mean-field, use approximations which calculate magnetizations and correlations at time t from statistics of data at time t?1, dynamical cavity method can use statistics of data at times earlier than t?1 to capture more correlations at different time steps. Extensive numerical experiments show that our inference method is superior to existing mean-field approaches on diluted networks. 相似文献
115.
Polarization-modulated analog photonic link with compensation of the dispersion-induced power fading 总被引:3,自引:0,他引:3
A novel integrable modulator consisting of a polarization modulator and a polarizer is proposed for constructing a high-performance analog photonic link. By adjusting a polarization controller placed before the modulator, both amplitude modulation and phase modulation with adjustable ratio between them are implemented. This feature is used to shift the peak of the frequency response of a dispersive link to any desired frequency, so the dispersion-induced power fading around the frequency is compensated. A proof-of-concept experiment is performed. The compensation of the dispersion-induced power fading in the proposed analog photonic link increases the spur-free dynamic range as large as 12.5 dB. 相似文献
116.
Zhiyu Chen Lianshan Yan Wei Pan Bin Luo Anlin Yi Jia Ye Hengyun Jiang Yinghui Guo 《Optics Communications》2012,285(9):2445-2450
A phase-sensitive-amplifier (PSA) using only one pump channel based on frequency non-degenerate four-wave-mixing (FWM) process for phase-shift-keying (PSK) signals is proposed and demonstrated. Theoretical analyses are given first. By optimizing power levels of three channels and parameters of the highly nonlinear fiber (HNLF), the PSA is able to restore the signal fidelity (down to a BER of 10? 9) as the input signal shows an error-floor with the BER of 10? 6. Moreover, the PSA for the multi-level PSK signals could be achieved by adjusting the phase relationship between two input signals. 相似文献
117.
X‐ray absorption near‐edge structure (XANES) of arsenate adsorption on TiO2 surfaces was calculated using self‐consistent multiple‐scattering methods, allowing a structural analysis of experimental spectra. A quantitative analysis of the effect of disorder revealed that the broadening and weakening of the characteristic absorption in experimental XANES was due to the structural disorder of the arsenate–TiO2 adsorption system. The success with calculating the scattering amplitude of a specific set of paths using the path expansion approach enables the scattering contributions of different coordination shells to the XANES to be sorted out. The results showed that the scattering resonances from high‐level shells inherently overlapped onto the first‐shell scattering amplitudes, and formed the fine structures in the XANES region. A variation in one oscillatory feature could be due to several structural changes affecting specific single/multiple‐scattering amplitudes. Therefore, direct assignments of spectral features with structural elements should be based on adequate theoretical analysis. 相似文献
118.
针对数字混沌密码序列发生器产生的二值序列局部范围内存在的周期特性评价难问题,提出一种新的周期特性分析方法——BSPD(binary sequence’s periodic detection)方法,用于评价二值序列具有的周期特性.该方法除可用于检测二值序列是否存在精确周期,或在部分时域范围内存在周期现象;还可检测出序列局部出现的周期性重叠模板,用于具体分析二值序列中周期现象的统计特征.一个基于经典Logistical映射的BSPD检验表明,该方法可以有效地定位一个类似随机混沌二值序列中蕴含的周期现象. 相似文献
119.
120.
采用高温熔融法分别制备了Yb3+/Ho3+,Yb3+/Tm3+和Yb3+/Ho3+/Tm3+共掺的碲酸盐玻璃。在980nm红外激光激发下,Yb3+/Ho3+/Tm3+共掺的玻璃样品显示了强的蓝光、绿光和红光发射,分别对应于Tm3+的1 G4→3 H6跃迁、Ho3+的5 F4(5 S2)→5I 8跃迁以及Ho3+的5 F5→5I 8和Tm3+的1 G4→3 F4跃迁。通过对比发现,Yb3+/Ho3+/Tm3+共掺样品中的红、绿光积分发射强度比值(3.95)明显大于Yb3+/Ho3+共掺样品(1.69),这是由于Ho3+和Tm3+间存在交叉弛豫过程3 H4(Tm3+)+5I 6(Ho3+)→3 F4(Tm3+)+5 F5(Ho3+)和3 F4(Tm3+)+5I 8(Ho3+)→3 H6(Tm3+)+5I 7(Ho3+)所致。在激发功率密度为8.2 W.cm-2时,Yb3+/Ho3+/Tm3+共掺样品的上转换发光色坐标值为x=0.345,y=0.338,非常接近于等能白光(x=0.333,y=0.333)。 相似文献