楔形导模共振滤波片的光谱分析

Spectral Characteristics of Guided-Mode Resonance Filter with Wedged Waveguide Layer

针对通信波段设计并制作了楔形波导层的导模共振滤波片（GMRF），分析并研究了其光谱特性。采用三角掩模板的方法进行离子束刻蚀，刻蚀一定次数后获得楔形波导层。光栅线条方向分为平行于和垂直于楔形波导层变化的方向。实验结果表明，对于两种结构，共振峰的位置与滤波片上的位置呈近似线性关系。光栅刻槽平行于楔形层变化的方向时共振峰的半峰全宽较光栅刻槽垂直于楔形层变化的方向时大。最终在20 mm的样品上，获得了线性渐变的Ta2O5楔形薄膜，其反射谱在1560～1600 nm范围内近似于线性变化。

We designed and fabricated guided-mode resonance filters （GMRFs） with a wedged waveguide layer, and analyzed their spectral characteristics. GMRF was etched for several times with the ion-beam etching technique and a triangle-shaped mask to obtain a wedged waveguide layer. The lines of photoresist gratings and thickness variation direction of the wedge-shaped waveguide layer are either parallel or perpendicular to each other. The experimental results show that the relationship between the resonance peak wavelength and position on the filter is approximately linear for the two samples. The half width at maximum in the case that the grating lines are parallel to the thickness variation direction of the wedge-shaped waveguide layer is larger than that in the case that the grating lines are perpendicular to the thickness variation direction. Through a linear gradation in the thickness of the Ta2O5 film across a distance of 20 mm, the spectral location of the reflection peaks was found to vary nearly linearly across the spectral range of 1560-1600 nm.