论文部分内容阅读
为了减小锗表面的反射,利用模式理论对锗衬底正方柱形亚波长结构的衍射特性进行了研究。结果发现,当周期较小时,占空比大于0.78对透射率的影响比较明显;周期大于0.25λ,零级透射率随周期的增大急剧下降,而总透射率随周期的增大变化不大;周期较小透射率随结构高度的变化呈余弦周期性,周期增大透射率随结构高度的变化呈余弦赝周期性,并且周期越大余弦赝周期性越明显;此外,周期较小时,可以实现大角度范围内的高的透射率,周期较大时,可以制备为窄带滤波器。
In order to reduce the reflection on the surface of germanium, the diffraction characteristics of the square-shaped sub-wavelength structure of germanium substrate were studied by the mode theory. The results show that when the duty cycle is larger than 0.78, the influence on the transmittance is obvious. When the period is more than 0.25λ, the zero-order transmittance decreases sharply with the increase of the period, while the total transmittance changes little with the increase of the period ; The smaller periodic transmittance is cosine periodic with the change of structure height, and the larger the periodicity is. The larger the periodicity is, the more significant the cosine pseudo periodicity is; the smaller the period, To achieve high transmittance within a wide range of angles, the cycle is large, can be prepared as a narrowband filter.