A Tunable Optical Bragg Grating Filter Based on the Droplet Sagging Effect on a Superhydrophobic Nanopillar Array
A Tunable Optical Bragg Grating Filter Based on the Droplet Sagging Effect on a Superhydrophobic Nanopillar Array
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基于超疏水纳米柱阵列液滴下垂效应的可调谐光学布拉格光栅滤波器
DOI：
10.3390/s19153324
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发表时间：
2019-08-01
期刊：
影响因子：
3.9
通讯作者：
Zheng, Zheng
中科院分区：
文献类型：
--
作者：
Zhang, Meng;Liu, Jiansheng;Zheng, Zheng
纳米结构被广泛应用于超疏水表面，以控制液体微滴的润湿状态。包括传感器在内的许多现代光学器件也与微米或纳米结构集成以增强功能。然而，很少有报道说，微流体和光学兼容地集成在相同的纳米结构中。本文提出了一种新型的微流体控制可调谐滤波器，该滤波器由位于平面波导顶部的周期性微/纳米柱阵列构成，并进行了数值模拟，其中周期性微/纳米柱同时具有布拉格光栅和超疏水功能。光栅的可调谐性是通过控制液滴进入周期柱的下垂深度来实现的。仿真结果表明，这种基于微流体的可调谐光流体波导布拉格光栅滤波器可以实现0.4nm的窄带宽和超过25 nm的宽波长调谐范围。此外，该方案可以很容易地修改为折射率传感器，每折射率单位的灵敏度为103 nm。
Nanostructures have been widely applied on superhydrophobic surfaces for controlling the wetting states of liquid microdroplets. Many modern optic devices including sensors are also integrated with micro- or nanostructures for function enhancement. However, it is rarely reported that both microfluidics and optics are compatibly integrated in the same nanostructures. In this paper, a novel microfluidic-controlled tunable filter composed of an array of periodic micro/nanopillars on top of a planar waveguide is proposed and numerically simulated, in which the periodic pillars endow both the Bragg grating and the superhydrophobic functions. The tunability of grating is achieved by controlling the sagging depth of a liquid droplet into the periodic pillars. Simulation results show that a narrow bandwidth of 0.4 nm and a wide wavelength tuning range over 25 nm can be achieved by such a microfluidic-based tunable optofluidic waveguide Bragg grating filter. Moreover, this proposed scheme can be easily modified as a refractive index sensor with a sensitivity of 103 nm per refractive index unit.