共查询到18条相似文献,搜索用时 187 毫秒
1.
2.
利用量子力学中的密度矩阵算符理论和迭代方法,导出莫尔斯(Morse)势阱中线性和三阶非线性光折射率改变的解析表达式,并以典型的GaAs/AlGaAs Morse势阱为例进行数值计算。数值结果表明,随着入射光强度增强,总的折射率改变将减少;随着势阱参数a的增大,总的折射率改变将减小;而随着载流子浓度的增加,总的折射率改变将增加。结果表明要获得较大的折射率改变,则需选取较小的入射光强度,较小的参数a,较大的载流子浓度,从而为实验研究提供理论依据。 相似文献
3.
利用量子力学中的密度矩阵算符理论导出了Pschl-Teller势阱中的线性与三阶非线性光学折射率的解析表达式。Pschl-Teller势阱中有两个可调参数κ和λ,势阱的形状及其非对称性会随势阱参数的取值不同而明显不同,从而其线性与非线性光学折射率变化的大小也会随势阱参数和入射光强的变化而呈规律性的变化。文章以典型的GaAs/AlGaAs势阱为例作了数值计算,数值计算结果表明,势阱的形状和入射光强对光学折射率有着重要的影响。 相似文献
4.
5.
利用量子力学中的密度矩阵算符理论导出了P schl-Teller势阱中的线性与三阶非线性光学折射率的解析表达式。P schl-Teller势阱中有两个可调参数κ和λ,势阱的形状及其非对称性会随势阱参数的取值不同而明显不同,从而其线性与非线性光学折射率变化的大小也会随势阱参数和入射光强的变化而呈规律性的变化。文章以典型的GaAs/AlGaAs势阱为例作了数值计算,数值计算结果表明,势阱的形状和入射光强对光学折射率有着重要的影响。 相似文献
6.
一维有限深方势阱能量本征方程的求解受限于超越方程,无法严格求解.本文将奇、偶宇称情况的超越方程归结为一个方程,自洽地给出两种近似解析解:一阶泰勒级数解和二次近似解.分析二者适用范围并做误差分析,发现泰勒级数解可以很好地理解能谱随量子数n平方变化的数值解(即,所谓n平方律),但在特定参数R下失效,该参数正比于势阱宽度乘以势阱高度开方.二次近似解对所有参数R都适用,能谱在大R极限下,可退化为精确求解的无限深势阱情况.对于任意参数R,二次近似波函数的保真度始终大于99.7%. 相似文献
7.
对有限深方势阱中的能级方程做一个简单的数学变换,从而将常用的图解法中的函数图像简化,使得有限深方势阱问题的物理图像变得更清晰,更有利于大家理解这个简单而重要的模型.文中还利用改进后的图解法简单讨论了一些有限深方势阱的性质. 相似文献
8.
9.
主要对量子力学一维有限深方势阱中运动粒子的束缚态存在条件进行讨论.通过求解定态薛定谔方程,得到粒子运动满足的超越方程,借助于Mathematica软件求解该超越方程得到粒子的能级结构,对粒子束缚态存在条件进行分析.结果表明,对于在一维有限深对称方势阱中运动的粒子,总会有束缚态的存在,和势阱的宽度、深度及粒子的质量无关.而在半壁有限深势阱中运动的粒子,出现束缚态是有条件的.并且分别给出了在两种势阱中粒子存在多个束缚态需要满足的条件. 相似文献
10.
一维有限深势阱、双势阱,一维势垒和双势垒是量子力学中最基本的模型,我们在工科物理教学中,利用计算机数值计算处理此类问题,进行了有益地探索并取得较好的效果。 相似文献
11.
U. Yesilgul F. Ungan E. Kasapoglu H. Sar? I. Sökmen 《Superlattices and Microstructures》2011,50(4):400-410
In this study, the changes in the optical absorption coefficients and the refractive index in a V-shaped quantum well have investigated theoretically. Within the effective mass approximation, the electronic structure of the V-shaped quantum well is calculated by numerical methods from the Schrödinger equation. Optical properties are obtained using the compact density-matrix approach. In the present work, the linear, third-order nonlinear and total absorption and refractive index changes investigated as a function of the quantum well width, the incident optical intensity, strengths of the magnetic and electric fields. Our results show that the magnetic and electric fields strengths, the quantum well width and incident optical intensity have a great effect on the optical characteristics of these structures. 相似文献
12.
The oscillator strength and the linear and third order nonlinear refractive index changes of a cylindrical quantum well wire under intense non-resonant laser field have been investigated within the effective mass-approximation by using a finite element method. We found that the laser amplitude, the incident light and the intersubband relaxation time have an important influence on the refractive index changes. 相似文献
13.
U. Yesilgul 《Journal of luminescence》2012,132(3):765-773
In this study, the changes in the refractive index and intersubband optical absorption coefficients in symmetric double semi-V-shaped quantum wells are investigated theoretically. The energy levels and the envelope wave functions of an electron confined in finite potential double semi-V-shaped quantum wells are calculated within the effective-mass approximation framework. The analytical expressions of the refractive index and intersubband optical absorption coefficients are obtained using the compact density matrix approach. The effects of the incident optical intensity and structure parameters, such as the barrier width, confinement potential and the well width, on the optical properties of the double semi-V-shaped quantum wells are investigated. The numerical results show that both the incident optical intensity and structure paremeters have a great effect on the optical characteristics of these structures. 相似文献
14.
Hassan Hassanabadi Hamed Rahimov Liangliang Lu Chao Wang 《Journal of luminescence》2012,132(5):1095-1100
In this study, a detailed investigation of the nonlinear optical properties such as optical absorption and refractive index change associated with intersubband transitions in a three-electron quantum dot in two dimensions in the presence of the Rashba spin–orbit interaction has been carried out. We present the exact wave functions and energy levels of the system. Numerical results on typical GaAs/AlGaAs materials show that the decrease of the quantum dot radius blueshifts and amplifies the absorption coefficients as well as the refractive index changes, as expected. Additionally, an increase of the optical intensity and relaxation time considerably changes the absorption coefficients and the refractive index changes. 相似文献
15.
A novel InGaAs/InAlAs coupled quantum well structure is proposed for large field-induced refractive index change with low absorption loss. In the case of low applied electric field of 15 kV/cm and low absorption loss (α≤ 100 cm-1), a large field-induced refractive index change (for transverse electric (TE) mode, △n = 0.012; for transverse magnetic (TM) mode, △n = 0.0126) is obtained in the structure at the operation wavelength of 1.55 μm. The value is larger by over one order of magnitude than that in a rectangular quantum well. The result is very attractive for semiconductor optical switching devices. 相似文献
16.
XIE Wen-Fang 《理论物理通讯》2015,63(5):635-640
The absorption spectra and the refractive index changes are calculated theoretically for an exciton in a core/shell quantum dot. The advantage of our methodology is that one can investigate the influence of the repulsive core by varying two parameters in the confinement potential. The dimensionality effect of exciton quantum dots on the optical absorptions has been studied. It has been found that in the same regime, the optical absorption intensities of excitons are much smaller for the core/shell quantum dots than for the two-dimensional quantum rings. The linear and the nonlinear optical absorption coefficients and refractive index changes have been examined with the change of the confinement potential. The results show that the optical absorptions and the refractive index changes are strongly affected by the repulsive core of core/shell quantum dots. Moreover, the calculated results also reveal that as the inner radius increases, the peak values of the absorption coefficients and the refractive index changes of an exciton will show the optical Aharonov–Bohm oscillation in core/shell quantum dots. 相似文献
17.
The performance of quantum well and quantum dot semiconductor optical amplifiers was theoretically investigated. The effects
on subpicosecond pulse propagation due to gain and refractive index dispersion, calculated using a microscopic polarization
equation and a reduced wave equation in the linear regime including the background refractive index dispersion, were used
in the comparison. In particular, the spectral shift and phase modulation imposed on the pulse were compared. It is shown
that quantum dot amplifiers suffer comparable spectral shifts to the quantum well amplifier, strong linear frequency chirp
and large pulse broadening. In quantum dot amplifiers with small inhomogeneous broadening, similar pulse break-up is shown
as that calculated for the quantum well amplifier. In quantum dot amplifiers with large inhomogeneous broadening, the background
refractive index dispersion makes the linear frequency chirp the dominant feature. In the light of our calculations, the advantages
and disadvantages of quantum dot and quantum well amplifiers are discussed. 相似文献
18.
The optical refractive index changes considering polaron effects in asymmetrical quantum wells are theoretically studied. It is shown that a pronounced optical refractive index changes dependence of the quantum well parameters can be obtained. Moreover, the theoretical values of the optical refractive index changes obviously increase when considering the electron-LO-phonon interaction. 相似文献