锗亚波长周期薄膜的光谱特性(英文)

Spectral properties of Ge subwavelength periodic membrane

宽带反射器和带通滤光片可以利用厚度固定为3.20μm的锗亚波长周期薄膜实现。强折射率调制的锗亚波长周期薄膜使得泄漏模共振的带宽增大,因此泄漏模共振TE11、TE21和TE30能够发生相互作用。通过改变光栅深度,可以在波长λ=10.60μm附近形成高反射宽带和透射带。利用泄漏模共振TE11、TE21和TE30之间的叠加产生增强反射效应,从而形成具有高反射率的反射宽带。利用这些泄漏模共振边缘的叠加产生共振增强透射效应,从而获得具有高透射率的透射带。在这两种情况下分别研究了光栅的未刻蚀和过刻蚀效应,结果表明,为了获得良好的光谱性能,刻蚀过程中应该避免过刻蚀情况。

Wideband reflector and bandpass filter can be obtained by using a Ge subwavelength periodic membrane with the thickness kept constant at 3.20 p.m. The strong refractive-index modulation of the Ge subwavelength periodic membrane yields increases bandwidth of the leaky mode resonances. Thus, the excitation of the leaky mode resonances TE^I, TE21 and TE30 may interact to form a broad reflection band or a transmission passband near A=10.60 Ixm by changing the grating thickness. By using the overlapping of the leaky mode resonances TEll, TE2~ and TE3o, enhanced reflection and a broad reflection band with high reflectivity were achieved. While using the overlapping of the edges of these multiple leaky mode resonances, a transmission passband with high transmissivity was obtained. The depth effects of underetching and overetching were investigated in both cases. The results show that an accurate etch depth control to avoid overetching is necessary to obtain good spectral performance from these devices.