New set of design rules for resonant refractive index sensors enabled by FFT based processing of the measurement data
New set of design rules for resonant refractive index sensors enabled by FFT based processing of the measurement data
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DOI：
10.1364/oe.24.007611
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发表时间：
2016-04-04
期刊：
影响因子：
3.8
通讯作者：
Kouloumentas, Christos
中科院分区：
文献类型：
--
作者：
Gounaridis, Lefteris;Groumas, Panos;Kouloumentas, Christos
在生物传感应用中，超高质量因子（q因子）是光学谐振腔实现高折射率分辨率和低检测限的先决条件。当共振位移的测量依赖于激光源的波长扫描和传统的数据处理方法时，需要超短的步骤，再加上高q因子要求使得这些生物传感器非常不切实际。在这项工作中，我们分析了一种基于快速傅立叶变换的替代处理方法，并通过蒙特卡罗模拟表明，在存在幅度和频谱噪声的情况下，系统的分辨率和检测极限可以提高2-3个数量级。更重要的是，这种改进在低q因子约104时是最大的，也存在于高腔内损耗和大扫描步长，使设计与低成本的芯片实验室技术兼容。采用微环谐振器作为模型腔，采用低q因子（104）、低幅值传输（0.85）和较大扫描步长（0.25 pm）的系统设计，我们发现，与依赖简单的峰值搜索处理方法的系统相比，可以实现接近0.01 pm的分辨率和接近10(-7)RIU的检测极限，将传感性能提高2个数量级以上。由于系统分辨率和灵敏度之间的权衡，即使将简单方法与超高q因子和超短扫描步骤相结合，检测极限也有所提高。初步的实验结果与数值研究的趋势一致。(C) 2016年美国光学学会
It is still a common belief that ultra-high quality-factors (Q-factors) are a prerequisite in optical resonant cavities for high refractive index resolution and low detection limit in biosensing applications. In combination with the ultra-short steps that are necessary when the measurement of the resonance shift relies on the wavelength scanning of a laser source and conventional methods for data processing, the high Q-factor requirement makes these biosensors extremely impractical. In this work we analyze an alternative processing method based on the fast-Fourier transform, and show through Monte-Carlo simulations that improvement by 2-3 orders of magnitude can be achieved in the resolution and the detection limit of the system in the presence of amplitude and spectral noise. More significantly, this improvement is maximum for low Q-factors around 104 and is present also for high intra-cavity losses and large scanning steps making the designs compatible with the low-cost aspect of lab-on-a-chip technology. Using a micro-ring resonator as model cavity and a system design with low Q-factor (104), low amplitude transmission (0.85) and relatively large scanning step (0.25 pm), we show that resolution close to 0.01 pm and detection limit close to 10(-7) RIU can be achieved improving the sensing performance by more than 2 orders of magnitude compared to the performance of systems relying on a simple peak search processing method. The improvement in the limit of detection is present even when the simple method is combined with ultra-high Q-factors and ultra-short scanning steps due to the trade-off between the system resolution and sensitivity. Early experimental results are in agreement with the trends of the numerical studies. (C) 2016 Optical Society of America