Guided-mode Resonance Filter for Micro-optic Spectrometer
Guided-mode Resonance Filter for Micro-optic Spectrometer
复制标题
微光学光谱仪用导模谐振滤波器
DOI：
10.1109/ectc32862.2020.00283
复制
发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Kintaka Kenji
中科院分区：
文献类型：
--
作者：
Inoue Junichi;Ura Shogo;Kintaka Kenji
光谱仪通常由衍射光栅和棱镜组成，并且为了高波长分辨率而变得大型化。不同波长的窄带通滤波器在衬底上的高密度集成可以预期产生超紧凑的光谱仪。我们专注于导模谐振（GMR）滤波器作为这样的滤波器。GMR滤波器由薄膜波导和亚波长光栅组成。不同滤波波长的GMR滤波器由于其折射率的周期性结构沿面内方向沿着扩展，可以集成在同一衬底上。另一方面，GMR滤波器通常需要数百微米的孔径尺寸和光束直径，并且不适合高密度集成。在本研究中，我们提出并研究了一种单层交叉光栅的巨磁阻滤波器作为小型窄带通滤波器。对宽带和窄带反射有贡献的不同导模彼此正交地传播。通过同时使用这些导模，两个反射在竞争波长处被抵消，从而导致高透射率。文中给出了设计实例和数值模拟结果。据预测，对于10微米直径的入射光束，在200 nm的阻带中获得15 nm的通带。
Spectrometers are usually composed of diffraction gratings and prisms, and become large in size for high wavelength resolution. High-density integration of narrowband-pass filters of different wavelengths on a substrate can be expected to produce an ultra-compact spectrometer. We focused on guided-mode resonance (GMR) filters as such filters. The GMR filter consists of a thin-film waveguide and a sub-wavelength grating. GMR filters of different filtering wavelengths can be integrated in the same substrate because their periodic structure in refractive index spread along in-plane direction. On the other hand, GMR filter normally needs an aperture size and beam diameter of hundreds of microns and is not suitable for high-density integration. In this study, we proposed and investigated a GMR filter of a single-layer cross grating for a compact narrowband-pass filter. Different guided modes contributing to the broadband and narrowband reflection propagate orthogonally each other. By using simultaneously these guided modes, both reflections are cancelled at the competing wavelengths, resulting in high transmittance. In this paper, design examples with numerical simulation results are presented. It was predicted that a passband of 15 nm was obtained in the stopband of 200 nm for an incident beam of a 10-micron diameter.