Radiation from a dipole embedded in a dielectric slab
Radiation from a dipole embedded in a dielectric slab
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DOI：
10.1109/2944.902140
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发表时间：
2000-11-01
影响因子：
4.9
通讯作者：
Brueck, SRJ
中科院分区：
文献类型：
--
作者：
Brueck, SRJ
本文对对称复层介质板内任意位置的任意取向电偶极子辐射给出了统一的解析处理方法。通过一次计算，计算了介质板内临界角度逃逸锥内的三维辐射模式和二维波导模式的发射。该模型适用于板层和包层之间的任意介电对比。数学方法使用了众所周知的复杂分析技术：三维辐射被描述为围绕分支切割的最陡下降积分，而二维波导模式对应于简单的极点。3-D和2-D模式之间的辐射功率划分在整个范围内进行评估，从适合二极管激光器的小介电对比度（小于或类似于1.1）到独立半导体板的非常大的介电对比度（类似于12-19）。与无界介质相比，总辐射功率的增强和抑制，取决于位置、平板宽度、电介质对比度和波长，发现平板宽度在波长数量级上，这些一维法布里-珀罗结构的最大增强类似于30%。对于较厚的平板，总辐射几乎是恒定的，等于在低介电对比度的无界介质中，同时仍然表现出一些调制，因为增加厚度允许额外的波导模式。
A unified analytical treatment of the radiation from an electric dipole of arbitrary orientation embedded at an arbitrary location within a symmetrically clad dielectric slab is presented. Both the emission into three dimensional (3-D) radiation modes, corresponding to emission within the critical angle escape cone within the dielectric slab, and into the two-dimensional (2-D) waveguide modes are evaluated from a single calculation. The model is valid for arbitrary dielectric contrast between the slab and the cladding. The mathematical approach uses well-known complex analysis techniques: the 3-D radiation is described by a steepest descents integration around branch cuts while the 2-D waveguide modes correspond to simple poles. The division of the radiated power between the 3-D and 2-D modes is evaluated across the entire range from small dielectric contrast appropriate to diode lasers (less than or similar to1.1) to the very large dielectric contrast of free-standing semiconductor slabs (similar to 12-19). Both enhancement and suppression, depending on position, slab width, dielectric contrast, and wavelength, of the total radiated power in comparison with that in an unbounded dielectric medium are found for slab widths on the order of a wavelength with a maximum enhancement of similar to 30% for these one-dimensional Fabry-Perot structures. For thicker slabs, the total radiation is almost constant and equal to that in the unbounded medium for low dielectric contrast while still exhibiting some modulation as increasing thickness allows additional waveguide modes.