超窄线宽导模共振滤波器的设计

Design of Resonant Filter for Ultra-Narrow Linewidth Guide Mode

亚波长光栅导模共振滤波器,具有高峰值反射率、低旁带反射和窄带等特点,能够实现基于高低折射率介质的滤波器所无法达到的独特功能。设计了中心波长为852nm的带有间隔层、线宽可控的超窄线宽导模共振滤波器,并分析了主要参数对反射光谱的影响。选择弱调制的介质作为光栅层,并在光栅层和波导层之间插入一层低折射率的介质作为间隔层来减小光栅层和波导层之间的耦合强度,进而使导模共振滤波器的线宽达到0.02nm的超窄程度,并且该结构中的光栅厚度、占空比等对反射光谱的影响极小,均利于其工艺制备。

Due to its characteristics of high peak reflectivity,low sideband reflection, narrowband and etc.,sub-wavelength grating guided mode resonance filter can realize special functions which cannot be realized by the high and low refractive index medium filter.In this paper,an ultra-narrow linewidth guided mode resonance filter with the central wavelength of 852nm was designed with spacing layer and controllable line width,and the influence of main parameters on the reflection spectrum was analyzed.Choosing weak modulated dielectric as the grating layer,and adding a layer of low refractive index medium as the spacer layer between the grating and the waveguide layer can reduce their coupling strength,and then make the linewidth of the guided mode resonance filter reach 0.02nm.And also both the thickness and duty ratio of the grating have less effect on its reflective spectrum,which is beneficial for the preparation process.