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941.
An effective feedback algorithm is proposed to dynamically control the gain spectra of multi-wavelength pumped broadband Raman amplifiers. Based on Raman coupling power equations, a simple saturation factor is introduced to achieve the adjusting matrix. By using this method, efficient pump adjustment can be carried out to accomplish wide-range dynamic gain spectrum control (larger than 22 dB dynamic range) as well as automatic gain clamping even for 90 nm bandwidth, highly-saturated RAs. Moreover, this algorithm can be well applied to different fiber types as well as pumping schemes. Some useful guidelines are also demonstrated. 相似文献
942.
With the aid of hydrodynamic model, a detailed analytical investigation is made of the stimulated Brillouin scattering (SBS) of the Stokes component of the scattered wave in piezoelectric-doped semiconductor plasma subjected to a magnetostatic field. The origin of the SBS process lies in the third-order nonlinear optical susceptibility arising due to the induced nonlinear current density and acoustic perturbations internally generated due to crystal properties such as piezoelectricity and electrostriction. Using the coupled mode theory of plasmas the effective refractive index and absorption coefficient are determined via the effective susceptibility. The influence of piezoelectricity, magnetostatic field and doping concentration has been explored. The analysis has been applied to both noncentrosymmetric and centrosymmetric crystals. Numerical estimates are made for n-type InSb crystal duly irradiated by a frequency doubled 10.6 μm CO2 lasers. Results are found to be well in agreement with available literature. The analysis establishes that a large nonlinear refractive index and small absorption coefficient can easily be obtained under moderate excitation intensity in piezoelectric doped magnetized semiconducting crystal, which proves its potential as candidate material for the fabrication of cubic nonlinear devices. 相似文献
943.
在CS2介质中观测到由声波引起的布里渊增强非简并四波混频(NFWM)和由分子取向栅产生的瑞利型NFWM.研究发现,分子取向栅与声波之间并不是相互独立的,声波的存在会破坏瑞利型NFWM和布里渊增强NFWM极化之间的相位关系.
关键词:
四波混频
布里渊散射
瑞利散射 相似文献
944.
分析了利用光纤中的受激布里渊散射(SBS)相位共轭效应进行激光腔内调Q,产生ns量级脉冲激光的原理,并对利用该效应产生的激光脉冲波形和脉冲形成过程进行了数值模拟,得到的脉冲波形与SBS相位共轭反射率随时间变化曲线基本一致,表明利用光纤中的SBS相位共轭作用调Q具有可行性。据此,对采用单模光纤(SMF)作为SBS池的掺Er3+调Q光纤激光器进行实验研究,当单模光纤长度为1.5 m时,在45 mW的抽运光功率下得到脉宽约2.6 ns,脉冲周期58.23 ns,平均功率7.35 mW的激光脉冲。进一步的研究表明:激光器中相位共轭镜的形成与SBS介质长度有关,SBS介质过长,斯托克斯线之间无固定的相位关系,不能形成相干叠加,SBS相位共轭腔不能形成; SBS介质过短,腔内正交偏振模光子寿命的改变使脉冲出现双峰现象。脉冲形成后其属性只与SBS动态属性有关。 相似文献
945.
946.
The acceleration of electrons by using a Bessel-Gaussian (BG) beam in vacuum is studied. It is shown that the axial electric
field of a linearly or circularly polarized BG beam of order n = 1 can be used to accelerate electrons. The general features of the acceleration of electrons by using a linearly or circularly
polarized BG beam, such as the transversal and axial electric-field components, phase velocity, slippage distance, accelerating
potential, and energy gain etc., are analyzed. 相似文献
947.
M. Suissa C. Place E. Goillot E. Freyssingeas 《The European physical journal. E, Soft matter》2008,26(4):435-448
Recent progresses in cellular biology have shown that the nucleus of a living cell is a structured integration of many functional
domains with a complex spatial organization. This organization, as well as molecular and biochemical processes, is time regulated.
In the past years many investigations have been performed using fluorescent microscopy techniques to study the internal dynamics
of the nucleus of a living cell. These investigations, however, have never focussed on the global internal dynamics of the
nucleus, which is still unknown. In this article we present an original light scattering experimental device that we built
to investigate this dynamics during biological processes. By means of this experimental set-up, we investigated the global
dynamics of the nucleus of a living cell treated with a DNA replication inhibitor. This dynamics presents different and independent
kinds of relaxation well separated in time that vary as a function of the cell cycle phases. 相似文献
948.
949.
由增益的三维公式出发,对高斯光束时的小信号增益进行了分析。对电子束截面远大于光束截面情况给出了解析的增益渐近公式;对电子束截面远小于光束截面的情况。给出了解析的增益近似公式,结果与用计算机模拟所得相符。 相似文献
950.
We present a general theory of the Brillouin lines in a fluid subject to a strong stationary heat flux. The combined effects of sound-absorbing walls and of large spatial inhomogeneities induced by the temperature gradient are computed for the first time. Nonequilibrium sound modes, constructed by WKB techniques, are used. No restrictions have to be made in the theory concerning the scattering geometry and the thermal equations of state. 相似文献