基于L形谐振腔MIM波导结构滤波特性的研究

Filter Characteristic Research of MIM Waveguide Based on L Shaped Resonator

设计了一种基于表面等离极化激元金属-介质-金属的L形谐振腔波导结构,并应用有限元方法研究了该结构的传输特性。数值计算结果表明,透射光谱中出现了明显的阻带,其滤波特性强烈地依赖于L形谐振腔结构的尺寸。相比于同尺度的水平放置的矩形谐振腔,L形谐振腔结构具有更高的品质因子,滤波效果更佳。随着L形谐振腔结构尺寸的增大,透射光谱发生红移;在L形谐振腔中充入折射率不同的介质,根据表面等离极化激元共振对L形谐振腔内折射率变化敏感特性,通过探测透射光谱中共振波长来探测介质折射率,该结构可广泛用于传感器方面。

A metal-insulator-metal （MIM） waveguide with L-shaped resonator is designed. The transmission properties of this resonator are numerically investigated by finite element method. The results show that the transmission properties of the L-shaped resonator depend on the length and the height of it. L-shaped cavity has better quality factor and better filtering effect compared with the horizontal rectangular cavity with the same size as L-shaped cavity. With the increase of the size of L-shaped cavity, spectrum exhibits a red shift. Filling the medium of different refractive index in L-shaped cavity, the MIM waveguide with L-shaped resonator allows a much more sensitive detection of small refractive index changes of the filled media inside L- shaped nano-cavity. It is easy to detect the refractive index of medium by detecting resonant wavelength in the transmission spectra, which reveals a potential sensors of the MIM waveguide with L-shaped nano-cavity.