Sub-wavelength waveguide Michelson interferometer sensors
Sub-wavelength waveguide Michelson interferometer sensors
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亚波长波导迈克尔逊干涉仪传感器
DOI：
10.1117/12.3003051
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发表时间：
2024
期刊：
影响因子：
--
通讯作者：
Chakravarty, Swapnajit
中科院分区：
文献类型：
--
作者：
Perera, Asela;Shen, Jianhao;Chakravarty, Swapnajit
在过去的十年中，绝缘体上硅或绝缘体上氮化硅平台中的倏逝场硅光子学已被有效地用于展示化学和生物传感器，其应用于检测癌症、病毒和传染病以及环境毒素的核酸和蛋白质生物标志物。通过平衡通过波导的高效低损耗传输的要求和增强光-物质相互作用，例如与谐振微腔中的高折射率材料表面上结合的分子，慢光和干涉仪几何形状，各种高灵敏度生物传感器已经在实验上被证明低至几个毫微微克/毫升。各种开槽微腔和波导已经在实验上得到证实。近年来，亚波长波导在晶格常数（Λ）<<（λ/2neff）的周期结构中表现出了接近~ 500 nm/RIU（RIU=折射率单位）的高体光谱灵敏度，其中neff是波长λ处的有效折射率。虽然大多数实验演示都是在亚波长环形谐振腔的几何形状，在这项研究中，除了实验演示干涉仪配置中的亚波长波导中的体光谱灵敏度~ 775 nm/RIU，我们还研究了可以在紧凑尺寸中达到灵敏度~70，000 nm/RIU的优化几何形状。与具有相同几何干涉仪臂长的马赫-曾德尔干涉仪（MZI）传感器相比，迈克尔逊干涉仪（MI）中的反射路径使光路长度加倍，并且因此在存在分析物的情况下有效地使相移加倍。与等效MZI相比，干涉条纹线宽变窄，因此能够从条纹光谱中辨别出分析物浓度的较小变化。
Evanescent field silicon photonics in a silicon-on-insulator or silicon-nitride-on-insulator platforms have been effectively utilized to demonstrate chemical and biosensors over the past decade with applications in the detection of nucleic acids and protein biomarkers for cancers, viruses and infectious diseases, and environmental toxins. By balancing the requirements for efficient low-loss transmission through the waveguide and enhancing light-matter interaction such as with molecules binding on the high index material surfaces in resonant microcavities, slow light and interferometer geometries, various high sensitivity biosensors have been experimentally demonstrated down to few femtograms/ml. various slotted microcavities and waveguides have been experimentally demonstrated. In recent years, subwavelength waveguides have demonstrated high bulk spectral sensitivities approaching ~500nm/RIU (RIU=refractive index unit) in periodic structures with lattice constant (Λ) <<(λ/2neff) where neffis the effective index at wavelength λ. While most experimental demonstrations have been in subwavelength ring resonator geometries, in this research, in addition to experimental demonstration of bulk spectral sensitivity ~775nm/RIU in subwavelength waveguides in interferometer configurations, we investigate optimized geometries that can reach sensitivities ~70,000nm/RIU in compact dimensions. In contrast to Mach-Zehnder interferometer (MZI) sensors of the same geometric interferometer arm lengths, the reflected path in Michelson interferometers (MI) doubles the optical path length, and thus effectively doubles the phase shift in the presence of an analyte. The interference fringe linewidths are narrowed compared to the equivalent MZI and would thus enable smaller changes in analyte concentration to be discerned from the fringe spectra.