The radiative properties of three different materials surfaces with one-dimensional microscale random roughness were obtained with the finite difference time domain method(FDTD) and near-to-far-field transformation.Th...The radiative properties of three different materials surfaces with one-dimensional microscale random roughness were obtained with the finite difference time domain method(FDTD) and near-to-far-field transformation.The surface height conforms to the Gaussian probability density function distribution.Various computational modeling issues that affect the accuracy of the predicted properties were discussed.The results show that,for perfect electric conductor(PEC) surfaces,as the surface roughness increases,the magnitude of the spike reduces and eventually the spike disappears,and also as the ratio of root mean square roughness to the surface correlation distance increases,the retroreflection becomes evident.The predicted values of FDTD solutions are in good agreement with the ray tracing and integral equation solutions.The overall trend of bidirectional reflection distribution function(BRDF) of PEC surfaces and silicon surfaces is the same,but the silicon's is much less than the former's.The BRDF difference from two polarization modes for the gold surfaces is little for smaller wavelength,but it is much larger for the longer wavelength and the FDTD simulation results agree well with the measured data.In terms of PEC surfaces,as the incident angle increases,the reflectivity becomes more specular.展开更多
锗是重要的红外光学材料,为减小锗表面的菲涅耳反射损耗,提高光利用率,研究了锗基底圆锥形微结构的减反射性能。基于时域有限差分法(Finite Difference Time Domain),并采用单因素法研究了微结构的占空比、周期、高度等结构参数与入射角...锗是重要的红外光学材料,为减小锗表面的菲涅耳反射损耗,提高光利用率,研究了锗基底圆锥形微结构的减反射性能。基于时域有限差分法(Finite Difference Time Domain),并采用单因素法研究了微结构的占空比、周期、高度等结构参数与入射角在8~12μm长波红外波段对反射率的影响,确定了微结构在低反射情况下较优的结构参数组合,其在整个波段范围内的平均反射率低于1%,远低于平板锗结构的35.47%,在9~11μm的波段范围内反射率低于0.5%,且光波在40°范围内入射时,圆锥形微结构的平均反射率仍然较低。将优化的圆锥形微结构与平板结构进行了对比,从等效折射率、反射场分布和能量吸收分布3方面进一步证实了圆锥形微结构在整个波段范围内优异的减反射性能。展开更多
基金Project(2009AA05Z215) supported by the National High-Tech Research and Development Program of China
文摘The radiative properties of three different materials surfaces with one-dimensional microscale random roughness were obtained with the finite difference time domain method(FDTD) and near-to-far-field transformation.The surface height conforms to the Gaussian probability density function distribution.Various computational modeling issues that affect the accuracy of the predicted properties were discussed.The results show that,for perfect electric conductor(PEC) surfaces,as the surface roughness increases,the magnitude of the spike reduces and eventually the spike disappears,and also as the ratio of root mean square roughness to the surface correlation distance increases,the retroreflection becomes evident.The predicted values of FDTD solutions are in good agreement with the ray tracing and integral equation solutions.The overall trend of bidirectional reflection distribution function(BRDF) of PEC surfaces and silicon surfaces is the same,but the silicon's is much less than the former's.The BRDF difference from two polarization modes for the gold surfaces is little for smaller wavelength,but it is much larger for the longer wavelength and the FDTD simulation results agree well with the measured data.In terms of PEC surfaces,as the incident angle increases,the reflectivity becomes more specular.
文摘锗是重要的红外光学材料,为减小锗表面的菲涅耳反射损耗,提高光利用率,研究了锗基底圆锥形微结构的减反射性能。基于时域有限差分法(Finite Difference Time Domain),并采用单因素法研究了微结构的占空比、周期、高度等结构参数与入射角在8~12μm长波红外波段对反射率的影响,确定了微结构在低反射情况下较优的结构参数组合,其在整个波段范围内的平均反射率低于1%,远低于平板锗结构的35.47%,在9~11μm的波段范围内反射率低于0.5%,且光波在40°范围内入射时,圆锥形微结构的平均反射率仍然较低。将优化的圆锥形微结构与平板结构进行了对比,从等效折射率、反射场分布和能量吸收分布3方面进一步证实了圆锥形微结构在整个波段范围内优异的减反射性能。
