指数型分层介质粗糙面光透射问题的微扰法

Optical Transmission from Exponentially Distributed Rough Surface of Layered Medium Using Perturbation Method

运用微扰法研究了平面波入射分层介质粗糙面的光透射问题,推出了不同极化状态的透射系数公式。采用指数型粗糙面模拟实际的分层介质粗糙面,结合其功率谱导出了平面波入射时的透射系数计算公式。通过数值计算得到了HH极化情形透射系数随透射光散射角变化的曲线。数值计算结果表明,底层介质介电常量对透射系数几乎没有影响;中间介质介电常量影响透射系数的大小及透射系数角分布曲线;中间介质厚度增大为原来的二倍时,曲线振荡的周期减小为原来的二分之一;粗糙面高度起伏均方根影响透射系数的大小、曲线振荡的振幅;粗糙面高度起伏相关长度既影响透射系数的大小、同时影响曲线的振荡行为;透射系数随入射波长的增大而振荡减小。

The optical transmission with plane wave incidence on the rough surface of layered medium is studied,the formulae of the transmission coefficient for different polarization states is derived using the perturbation method.An exponentially distributed rough surface is presented for describing the practical rough surface of layered medium,the transmission coefficient of HH polarization with the scattering angle of transmission wave is obtained by numerical calculation.The numerical results show that the transmission coefficient almost does not change with permittivity of the substrate medium.The magnitude and curve of the angular distribution for the transmission coefficient are affected by the the permittivity of intermediate medium.As the mean layer thickness of intermediate medium increases twice over,the period of the curves will decrease one half.The rough surface influences the magnitude of the transmission coefficient and the amplitude of the curve,the correlation length of the rough surface influences the magnitude of the transmission coefficient,the amplitude and varying trend of the curves.The transmission coefficient decreases oscillatorily with increase of the incident wavelength.