双节MIM结构表面等离子体窄带光学滤波器  

Narrow-Band Filter of Surface Plasmon Based on Dual-Section Metal-Insulator-Metal Structure

作　　者：罗昕[1] 邹喜华[1] 温坤华[1] 潘炜[1] 闫连山[1] 李孝峰[2] 

机构地区：[1]西南交通大学信息光子与通信研究中心,四川成都610031 [2]苏州大学现代光学技术研究所,江苏苏州215006

出　　处：《光学学报》2013年第11期237-241,共5页Acta Optica Sinica

基　　金：教育部新世纪优秀人才支持计划(NCET-12-0940);国家自然科学基金(91233119);教育部春晖计划(Z2011124);成都市科技计划(12DXYB287JH-005)

摘　　要：基于双节金属-绝缘体-金属(MIM)结构,设计了一种表面等离子体(SPs)型窄带光学滤波器。该滤波器有两块金属夹层,两夹层之间由一块金属薄膜分隔的两节绝缘介质层组成;每节绝缘介质层包含结构一致的4个周期,每个周期由一个高折射率绝缘介质和一个低折射率绝缘介质构成。光波进入到该波导结构同时激发出不同谐振波长下的长程表面等离子体(LRSPs)和短程表面等离子体(SRSPs),形成多个透射峰。在整个双节绝缘介质层中间处插入一块金属薄膜,不仅增大金属薄膜两端光波的耦合距离、压缩透射峰的3dB信道带宽,而且能实现LRSPs/SRSPs共振波长的蓝移(红移),使特定波长处两者的透射峰发生重合,形成具有高对比度的窄带透射峰。有限时域差分法研究表明:在1.3μm波长处获得3dB信道带宽为9.2nm的窄带透射峰,其峰-谷对比度为37.2dB;进一步将金属薄膜宽度增加到55nm,3dB信道带宽可降至7.2nm,峰-谷对比度升至40.1dB,获得了良好的窄带滤波性能。A narrow-band plasmonic filter based on dual-section metal-insulator-metal （MIM） structure is proposed, which consists of two metal layers and two insulator layer sections separated by a metal film. Each layer section contains four insulator periodic units structured by alternately stacking two insulators with different refractive indices. In the filter, both long range surface plasmons （LRSPs） and short range surface plasmons （SRSPs） at different resonant wavelengths are stimulated under the condition of light injection. Some transmission peaks are formed at a specific wavelength where the resonance condition for the LRSPs or SRSPs is satisfied. The insertion of a metal film into the two insulator layer sections enables us to increase the coupling distance of both ends of the metal film and to reduce the 3 dB bandwidth of transmission peak. At the same time, the resonance wavelength of LRSPs （SRSPs） will be blue-shifted （red-shifted）, so that the transmission peaks of LRSPs and SRSPs overlap at a specific wavelength, resulting in the generation of a narrow-band transmission peak with high peak-to-notch contrast ratio. The transmission characteristics of the proposed filter are numerically investigated by using the finite-difference time-domain （FDTD） method. A transmission peak with a 3 dB bandwidth of 9.2 nm and a peak-to-notch contrast ratio about 37.2 dB is confirmed in the 1.3 μm range. By further increasing the width of metal film to 55 nm, the 3 dB bandwidth can be reduced to 7.2 nm and the peak-to-notch contrast ratio can be increased to 40.1 dB. Therefore, excellent narrow-band filtering performance is obtained.

关 键 词：表面光学 窄带滤波器 金属-绝缘体-金属型波导 表面等离子体 

分 类 号：TN713[电子电信—电路与系统]