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排序方式: 共有102条查询结果,搜索用时 15 毫秒
21.
半导体激光器的M2因子可以小于1 总被引:3,自引:2,他引:1
根据Porras的非傍轴矢量矩理论,对双异质结半导体激光器的光束质量进行了研究.结果表明,在有源层厚度da远小于波长λ的条件下,半导体激光器的M2因子可以小于1,并且没有下限. 相似文献
22.
Based on the vector angular spectrum representation of optical beam and the method of stationary phase, the analytical TE and TM terms of vector Gaussian beam have been presented in the far field. By using the local polarization matrix, the polarization properties of the TE and TM terms in the far field are investigated, and it is found that the degree of their polarization is only determined by the spatial location. When the source is completely polarized, the TE and TM terms are both completely polarized in the far field. When the source is completely unpolarized, the TE and TM terms in the far field are partially polarized. The whole beam is also partially polarized except on the propagating axis. Moreover, the degrees of polarization of TE and TM terms are both larger than that of the whole beam.[第一段] 相似文献
23.
ZHOUBang-Rong 《理论物理通讯》2004,42(1):79-82
It is shown that by means of canonical operator approach the Ward-Takahashi identity (WTI) at finite temperature T and finite chemical potential μ for complete vectorial vertex and complete fermion propagator can be simply proven, rigorously for Quantum Electrodynamics, and approximately for Quantum Chromodynamics, where the ghost effect in the fermion sector is neglected. The WTI shown in the real-time thermal matrix form will give definite thermal constraints on the imaginary part of inverse complete Feynman propagator including self-energy for fermion and will play an important role in relevant physical processes. When the above inverse propagator is assumed to be real, the thermal WTI will essentially be reduced to its form at T=μ=0 thus one can use it in the latter‘s form. At this point, a practical example is indicated. 相似文献
24.
基于矢量瑞利-索末菲衍射积分公式,得出了波动方程的一个解,它代表矢量非傍轴离轴高斯光束,其在自由空间的传输方程表示为解析的结果.矢量非傍轴离轴高斯光束的轴上和远场公式,矢量非傍轴高斯光束的传输方程,以及傍轴的结果都可作为一般表达式的特例而得出.研究表明,f参数对光束的非傍轴特性有重要影响,而离心参数也影响非傍轴行为.与共轴情况不同的是,对离轴情况,在y方向存在场的纵向分量.
关键词:
激光光学
矢量非傍轴离轴高斯光束
瑞利-索末菲衍射积分
f参数
离轴参数 相似文献
25.
AbstractDue to the uncertainty principle, a function cannot be simultaneously limited in space as well as in frequency. The idea of Slepian functions, in general, is to find functions that are at least optimally spatio-spectrally localized. Here, we are looking for Slepian functions which are suitable for the representation of real-valued vector fields on a three-dimensional ball. We work with diverse vectorial bases on the ball which all consist of Jacobi polynomials and vector spherical harmonics. Such basis functions occur in the singular value decomposition of some tomographic inverse problems in geophysics and medical imaging. Our aim is to find band-limited vector fields that are well-localized in a part of a cone whose apex is situated in the origin. Following the original approach towards Slepian functions, the optimization problem can be transformed into a finite-dimensional algebraic eigenvalue problem. The entries of the corresponding matrix are treated analytically as far as possible. For the remaining integrals, numerical quadrature formulae have to be applied. The eigenvalue problem decouples into a normal and a tangential problem. The number of well-localized vector fields can be estimated by a Shannon number which mainly depends on the maximal radial and angular degree of the basis functions as well as the size of the localization region. We show numerical examples of vectorial Slepian functions on the ball, which demonstrate the good localization of these functions and the accurate estimate of the Shannon number. 相似文献
26.
Tomasz Czyszanowski Maciej Dems Hugo Thienpont Krassimir Panajotov 《Optical and Quantum Electronics》2007,39(4-6):427-433
A three-dimensional, full vectorial model has been applied for investigation the modal characteristics of a phosphide photonic-crystal
vertical-cavity surface-emitting diode laser. The photonic crystal has been defined as a regular, hexagonal net of holes,
etched in the upper, p-type Distributed Bragg Reflector of the laser. The electromagnetic field has been confined to the active region by a single
defect of the photonic crystal providing overlapping with carriers funneled by a tunnel junction. We have determined the range
of design parameters, which provide single mode operation. 相似文献
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基于Porras提出的光传输的非傍轴矢量矩理论,推导出初始圆偏振的非傍轴矢量拉盖尔-高斯(LG)光束的特征参数,包括束宽、远场发散角和M2因子等的公式,并表示为级数求和形式.非傍轴矢量高斯光束公式作为特例给出.研究表明,基于二阶矩定义的束宽按双曲线规律传输,当w0/λ→0(w0为束宽,λ为波长)时,远场发散角θ趋于90°,大于非傍轴标量理论预示的值63.435°.非傍轴矢量LG光束的M2因子不仅与模指数p有关,而且还与w0/λ有关.最后,对非傍轴矢量LG光束和非傍轴标量LG光束的传输作了比较,结果表明在w0/λ较小时,矢量效应对远场发散角的影响十分显著.对θ→90°引起的问题和非傍轴矢量矩理论的适用范围,以及解决问题的可能途径作了分析和讨论.
关键词:
非傍轴矢量拉盖尔-高斯光束
圆偏振
非傍轴矢量矩理论
光束参数 相似文献