High sensitivity refractive index sensing with strong light confinement in high-aspect-ratio U-cavity arrays
High sensitivity refractive index sensing with strong light confinement in high-aspect-ratio U-cavity arrays
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高纵横比 U 型腔阵列中具有强光限制的高灵敏度折射率传感
DOI：
10.1016/j.snb.2014.05.033
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
and Jean-Jacques Delaunay
中科院分区：
文献类型：
--
作者：
Yaerim Lee;Etsuo Maeda;Ya-Lun Ho;Shigenori Fujikawa;and Jean-Jacques Delaunay
提出了一种由金高宽比纳米鳍制成的U型腔作为近红外折射率敏感元件。传感机制是基于U型腔阵列的谐振波长在腔周围介质变化时的偏移。U型腔阵列支持腔中的强光限制，如由腔的光功率流中的涡旋的形成所证明的。腔体的底部金层使得能够利用强大的涡旋进行有效的光捕获，如腔体的低功率泄漏所证明的。强光限制引起共振，表现出急剧的反射率下降。凹陷波长的值由腔的几何形状确定，因此很容易预测。光的入射角上的共振条件不受限制，使得该结构提供很小的角度依赖性。当周围介质的折射率增加时，零级反射率的共振凹陷向更高的值移动。U型腔阵列的制造与快速和具有成本效益的制造工艺，如光刻，金溅射，等离子体蚀刻。在不同折射率的介质下，在近红外波长范围内测量零级反射光谱，以量化折射率变化的敏感性。U型腔阵列实现了743 nm的每折射率单位的灵敏度与模拟结果吻合得很好。
U-cavities made of gold high-aspect-ratio nano-fins are proposed as a sensitive refractive index sensing element in the near-infrared region. The sensing mechanism is based on the shift of the resonance wavelength of arrays of the U-cavities upon change in the cavity surrounding medium. The U-cavity arrays support strong light confinement in the cavities as evidenced by the formation of vortices in the optical power flow of the cavities. The bottom gold layer of the cavities enables efficient light trapping with powerful vortex, as evidenced by the low power leakage of the cavities. The strong light confinement gives rise to resonance exhibiting sharp reflectance dips. The values of the dip wavelengths are determined from the geometry of the cavity and therefore are easily predicted. The condition for resonance on the incidence angle of light is not restrictive, so that the structure offers little angular dependency. The resonance dips of the zero-order reflectance shift toward higher values when the refractive index of the surrounding medium is increased. U-cavity arrays were fabricated with fast and cost-effective manufacturing processes such as photolithography, gold sputtering, and plasma etching. Zero-order reflectance spectra were measured in the near-infrared wavelength range under different refractive index media in order to quantify the sensitivity to refractive index change. The U-cavity arrays achieved a sensitivity of 743 nm per refractive index unit in good agreement with simulation results.