锗衬底红外抗反射亚波长结构的研究

Studies of Infrared Antireflection Subwavelength Structure on Ge Substrate

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 solve the reflection of the germanium surface,the square pillar subwavelength structures are analyzed and designed by model theory.The results show that filling factors that are bigger than 0.78 have a more important effect on transmittance when periods is smaller.Zero transmittance decreases so quickly with periods increasing while sum transmittance decreases so few with periods increasing when periods are bigger than 0.25λ.The relationships between transmittance and depth are cosine when the period is smaller while the relationships between transmittance and depth are pseudo cosine when period is bigger.Besides transmittance is high within wide incident angles when the period is smaller,when the period is bigger the subwavelength structures can be made narrowband filter.