共查询到20条相似文献,搜索用时 109 毫秒
1.
2.
3.
为解决四波混频法测量光纤非线性系数未考虑泵浦消耗而导致结果不准确的问题,提出了一种在简并四波混频情况下测量非线性系数的方法.根据光纤中简并的四波混频理论,推导出了考虑泵浦消耗和光纤损耗的椭圆方程.通过设定数值计算所需的各个参量并利用简单的数学方法分析了计入泵浦消耗、光纤损耗的必要性,得到被测光纤的非线性系数,与Optisystem的仿真结果一致.研究表明,这种改进的测量方法不但适用于小信号情形下的四波混频过程,还可以应用于出现参量饱和现象的场合,为进一步设计光纤2R再生器件提供了重要依据. 相似文献
4.
为解决四波混频法测量光纤非线性系数未考虑泵浦消耗而导致结果不准确的问题,提出了一种在简并四波混频情况下测量非线性系数的方法.根据光纤中简并的四波混频理论,推导出了考虑泵浦消耗和光纤损耗的椭圆方程.通过设定数值计算所需的各个参量并利用简单的数学方法分析了计入泵浦消耗、光纤损耗的必要性,得到被测光纤的非线性系数,与Optisystem的仿真结果一致.研究表明,这种改进的测量方法不但适用于小信号情形下的四波混频过程,还可以应用于出现参量饱和现象的场合,为进一步设计光纤2R再生器件提供了重要依据. 相似文献
5.
6.
7.
8.
9.
采用放大传递函数理论模拟和分析了基于自发参量下转换产生参量荧光的光谱分布特性,结果表明:非简并态下随着相位匹配角的增大,参量荧光空间强度角分布呈现变大趋势,而整个荧光光谱成分的分布逐渐倾向于连续的弱分布状态.对于简并态附近出现荧光光谱具有宽带宽集中分布的特征,采用两种不同的抽运光脉冲进行了对比分析,并且对此特征关于相位匹配角变化的敏感特性,采用放大传递函数和光谱成分概率分布函数两种不同理论的模拟结果一致.
关键词:
参量下转换
参量荧光 相似文献
10.
从原子和场模的密度算符的主方程出发,应用Haake和Lewenstein所发展的原子变量绝热消除的算符方法,导出了简并双光子激光光场Wigner函数的福克-普朗克(Fokker-Planck)方程及其稳态解.利用稳态解的高斯近似,求得了在不同泵浦强度下,光子统计的解析结果如数值结果,并与前人的结果作了比较. 相似文献
11.
Xue-Hua Wang Ben-Yuan Gu 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,24(3):323-326
The analytic solution to the wave equation for small-signal sum-frequency process is derived in 2D χ
(2)
photonic crystals with use of the Green function method. It is predicted that the sum-frequency electrical field at quasi-phase
matching (QPM) resonance is proportional to the angle-dependent effective crystal length. This implies that multiple wavelength
QPM frequency conversion with controllable intensity output can be realized in a single 2D χ
(2)
photonic crystal. It is revealed that efficient frequency conversion requires both the QPM and the proper structure matching.
A novel double-circle construction, different from the conventional Ewald construction, is presented to reflect important
QPM processes. It is also shown that the QPM resonance tuning of second-harmonic generation can operate over the whole transparent
wavelength range of crystals.
Received 19 April 2001 相似文献
12.
Tunable ultraviolet radiation by second-harmonic generation in periodically poled lithium tantalate 总被引:2,自引:0,他引:2
We describe electric-field poling of fine-pitch ferroelectric domain gratings in lithium tantalate and characterization of nonlinear-optical properties by single-pass quasi-phase-matched second-harmonic generation (QPM SHG). With a 7.5-microm-period grating, the observed effective nonlinear coefficient for first-order QPM SHG of 532-nm radiation is 9 pm/V, whereas for a grating with a 2.625-microm period, 2.6 pm/V was observed for second-order QPM SHG of 325-nm radiation. These values are 100% and 55% of the theoretically expected values, respectively. We derive a temperature-dependent Sellmeier equation for lithium tantalate that is valid deeper into the UV than currently available results, based on temperature-tuning experiments at different QPM grating periods combined with refractive-index data in the literature. 相似文献
13.
Nguyen Dinh Dang 《Zeitschrift für Physik A Hadrons and Nuclei》1987,327(1):41-49
A set of equations for Green functions based on the exact Hamiltonian of the Quasiparticle-Phonon Model (QPM) for spherical even-even nuclei is obtained. The relation between this new set and the usual equations employed so far in the QPM is discussed. In particular a comparison between the obtained secular equation for excited state energy and the one used so far in the QPM for the case, when the excited state wave function consists of one- and two-phonon components, is made. The numerical evaluation performed in the schematic two level model showed that the difference between the results given by the calculation with the exact Hamiltonian and those based on the approximated Hamiltonian was remarkable in nonmagic nuclei. 相似文献
14.
We find exact solutions to the Wheeler-DeWitt equation, for a certain factor ordering. They have the form =We
± for class A Bianchi models, where is a solution to the classical Hamilton-Jacobi equation, generalizing the only known solution of Moncrief and Ryan for the Bianchi type IX model in standard quantum cosmology. The same kind of solution has also been found in supersymmetric quantum cosmology. 相似文献
15.
We investigated angular tuning of quasi-phase-matching (QPM) second-harmonic generation (SHG), in order to extend the tunable range of QPM and to combine the advantages of QPM and birefringence phase-matching. The direction of the input fundamental wave vector was detuned from the QPM grating vector along the crystallographic Z-axis of a periodically-poled lithium niobate (PPLN) crystal in the XY- and XZ-planes. A?larger tuning range of SHG was obtained for the detuning in the XZ-plane, continuously shifting the QPM peak of the fundamental wavelength from 1524 to 1595?nm by changing the detuning angle from 0° (parallel to X-axis as conventional QPM) to 23.2°. 相似文献
16.
We consider the Dyson equation associated with the BCS superconducting state from a mathematical point of view. The Dyson equation gives rise to a modified gap equation that is similar to the BCS gap equation, but with a different kernel. We first show that for strong coupling (such that the McMillan parameter ||1) both the real and imaginary parts of the solution (E) of the modified gap equation alternate in sign as function of the excitation energyE, the periods
being 40 for positive and 40/3 for negative . (0 is the frequency of an Einstein spectrum of phonons). A closed, algebraic approximation to (E) is 2||0log[cotan(E/
)]. Finally, the poles of the kernel of the integral equation are located in the complex-E plane. For the new-type, oscillatory solution of the modified gap equation the analogue of the causal (zero-temperature) Green's function is shown to have different analytic properties from those of the smooth Eliashberg solution of BCS theory. 相似文献
17.
V. J. Lee 《Foundations of Physics》1980,10(1-2):77-107
The time-dependent Schrödinger equation has been derived from three assumptions within the domain of classical and stochastic mechanics. The continuity equation isnot used in deriving the basic equations of the stochastic theory as in the literature. They are obtained by representing Newton's second law in a time-inversion consistent equation. Integrating the latter, we obtain the stochastic Hamilton-Jacobi equation. The Schrödinger equation is a result of a transformation of the Hamilton-Jacobi equation and linearization by assigning the arbitrary constant =2mD. An experiment is proposed to determine and to test a hypothesis of the theory directly. A mathematical apparatus is formulated from the Jacobian formalism to derive physical parameters from (x, t) and to obtain operators for the boundary cases of the theory. The operator formalisms are compared by means of a well-known solution in the quantum theory. 相似文献
18.
Li-yeng Sung 《Mathematical Physics, Analysis and Geometry》1999,2(1):1-24
We prove that the solution of the Cauchy problem for the Kadomtsev–Petviashvili-I Equation obtained by the inverse spectral method belongs to the Sobolev space Hk(R2) for k 0, under the assumption that the initial datum is a small Schwartz function. This solution is shown to be the unique solution within a class of generalized solutions of the Kadomtsev–Petviashvili-I equation. 相似文献
19.
We introduce a method of solving initial boundary value problems for linear evolution equations in a time-dependent domain, and we apply it to an equation with dispersion relation omega(k), in the domain l(t)相似文献
20.
We continue the analysis of the conjugate equation for the generating function of a Gibbs random point field corresponding to a stationary solution of the classical BBGKY hierarchy. This equation was established and partially investigated in the preceding papers under the same title. In the present paper we reduce a general theorem about the form of solutions of the conjugate equation to a statement which relates to a special case where the interacting particles constitute a quasi—one dimensional configuration. 相似文献