Laakmann K D, Steier W H
Appl Opt. 1976 May 1;15(5):1334-40. doi: 10.1364/AO.15.001334.
The field configurations and propagation constants of the normal modes of a hollow rectangular dielectric waveguide have been determined. In addition, the coupling coefficients of a Gaussian free-space mode into the normal modes of a square guide were calculated. The attenuation of each mode is found to be inversely proportional to the cube of the guide aperture 2alpha and proportional to the square of the free-space wavelength lambda. For a hollow dielectric square guide with 2alpha = 1 mm and lambda = 10.6 microm, an attenuation of 0.140 dB/m is predicted for SiO(2) and 0.032 dB/m for BeO. All modes are found to be hybrid modes, although they very closely approximate linearly polarized TEM modes.
已确定空心矩形介质波导正常模式的场配置和传播常数。此外，还计算了高斯自由空间模式与方形波导正常模式之间的耦合系数。发现每种模式的衰减与波导孔径2α的立方成反比，与自由空间波长λ的平方成正比。对于一个2α = 1毫米且λ = 10.6微米的空心介质方形波导，预测SiO₂的衰减为0.140 dB/m，BeO的衰减为0.032 dB/m。尽管所有模式都非常接近线性极化TEM模式，但实际上都是混合模式。
