Huang Lijun, He Dajiang, Mi Xianwu, Ding Jianqun, Chen Shenghai, Peng Xiaoliang
Appl Opt. 2018 Nov 20;57(33):9822-9827. doi: 10.1364/AO.57.009822.
A one-dimensional photonic crystal elliptical-hole tapered low-index-mode nanobeam cavity sensor fully encapsulated in a water environment is proposed. In the proposed structure, to confine the light in the low-index region and enhance the light-matter interaction, a tapered major axis of the elliptical hole away from the nanobeam cavities center is optimized. Through a three-dimensional finite-difference time-domain simulation, the results show that the low-index-mode of the middle geometry cell is confined in the photonic bandgap of two-sided cells. The highest quality factor of 6.04×10 is achieved when 13 tapered segments and 5 mirror segments are placed at both sides of the host waveguide. The proposed nanobeam structure theoretically possesses a sensitivity of 244.7 nm/RIU (refractive index unit) in a water environment. Moreover, an ultra-compact footprint of 6.4 μm×0.85 μm is achieved, which is only half of the size compared to the best value reported for the nanobeam structure. The results indicate that it is a promising sensor for excellent on-chip sensing with respect to the very small footprint.
提出了一种完全封装在水环境中的一维光子晶体椭圆孔锥形低折射率模式纳米束腔传感器。在所提出的结构中，为了将光限制在低折射率区域并增强光与物质的相互作用，优化了远离纳米束腔中心的椭圆孔的锥形长轴。通过三维时域有限差分模拟，结果表明中间几何单元的低折射率模式被限制在两侧单元的光子带隙中。当在主波导两侧放置13个锥形段和5个镜像段时，可实现6.04×10的最高品质因数。所提出的纳米束结构在理论上在水环境中具有244.7 nm/RIU（折射率单位）的灵敏度。此外，实现了6.4μm×0.85μm的超紧凑占位面积，与报道的纳米束结构的最佳值相比，尺寸仅为其一半。结果表明，就非常小的占位面积而言，它是一种用于出色片上传感的有前途的传感器。
