Are slot and sub-wavelength grating waveguides better than strip waveguides for sensing?
Are slot and sub-wavelength grating waveguides better than strip waveguides for sensing?
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DOI：
10.1364/optica.5.001046
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发表时间：
2018-09-20
期刊：
影响因子：
10.4
通讯作者：
Hu, Juejun
中科院分区：
文献类型：
--
作者：
Kita, Derek M.;Michon, Jerome;Hu, Juejun
狭缝和亚波长光栅（SWG）波导将光限制在波导芯材料之外的独特能力在其应用于化学和生物传感方面引起了极大的兴趣。然而，在这些结构中的侧壁粗糙度引起的散射损失相比，条形波导的高灵敏度，使人怀疑它们的功效。在这篇文章中，我们试图解决的争议，绝缘体上硅（SOI）光子器件通过定量比较各种波导几何形状的传感性能，通过品质因数，我们得出每种模式的传感。这些方法（可以很容易地应用到其他材料系统）考虑到模式限制和粗糙度散射损失，后者是使用体积电流（绿色函数）方法与第一玻恩近似计算。用于基于标准220 nm SOI平台的电信波长器件（λ = 1550 nm），其传播损耗主要受随机线边缘侧壁粗糙度散射的限制，我们的模型预测，适当设计的TM偏振条形波导要求折射和吸收光谱的最佳性能，而对于波导增强拉曼光谱，优化的槽波导表现出超过其它波导几何结构的> 5倍的性能增强。(C)根据OSA开放获取出版协议的条款，2018年美国光学学会
The unique ability of slot and sub-wavelength grating (SWG) waveguides to confine light outside of the waveguide core material has attracted significant interest in their application to chemical and biological sensing. However, a high sensitivity to sidewall-roughness-induced scattering loss in these structures compared with strip waveguides casts doubt on their efficacy. In this article, we seek to settle the controversy for silicon-on-insulator (SOI) photonic devices by quantitatively comparing the sensing performance of various waveguide geometries through figures of merit that we derive for each mode of sensing. These methods (which may be readily applied to other material systems) take into account both modal confinement and roughness scattering loss, the latter of which is computed using a volume-current (Green's function) method with a first Born approximation. For devices based on the standard 220 nm SOI platform at telecommunication wavelengths (lambda = 1550 nm), whose propagation loss is predominantly limited by random line-edge sidewall roughness scattering, our model predicts that properly engineered TM-polarized strip waveguides claim the best performance for refractometry and absorption spectroscopy, whereas optimized slot waveguides demonstrate >5x performance enhancement over the other waveguide geometries for waveguide-enhanced Raman spectroscopy. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement