基于局域模耦合效应的近红外波段光子晶体生物传感器的研究

Photonic crystal biosensor has attracted much attention because of its high sensitivity, high resolution, high integration and no-label detection. The main principle is based on the sensitive alteration of the resonant frequency supported by the photonic crystal microcavity to the slight changes of the environmental refractive index, but the alteration of light transmittance has not been effectively used. In this project, we study the coupling characteristics between localized modes, when different kinds of disease markers are attached around different defects, different types of biological bacteria concentration information can be obtained by analyzing the change of frequency position and exact light transmittance of multiple transmission peaks at the same time. We study the one-dimensional photonic crystal biosensor structure based on the coupling of defect modes, also study the two-dimensional structures based on the coupling of central defect mode and the surface mode, and coupling-cavity optical waveguide based on the coupling effect between the multi-band narrow bands. The biosensing characteristics of three-dimensional woodpile photonic crystal structures with the central defect mode and surface mode are also studied. Based on the SOI substrate, the silicon-pillar-typed photonic crystal biosensor is proposed in the project, where the background environment is free-flowing liquid, and it is more conducive to the dynamic real-time detection of the biological bacteria concentration. On the basis of theoretical results, the electron beam lithography combined with inductively coupled plasma etching system is utilized to experimentally fabricate the corresponding biosensor structure and the microspectral measurement system combined with microfluidic technology is used to measure the optical sensing performance.

光子晶体生物传感器因具有高灵敏度、高分辨率、高集成度和无标签检测等特点，近年来受到了人们的广泛关注。其主要原理是通过探测光子晶体微腔谐振频率的位置变化分析微腔周围环境折射率的细微变化，然而透射光强的变化情况并没有被加以有效利用。本项目拟研究光子晶体多个局域模间的耦合特性，通过对多个透射峰频率位置和透射光强的变化分析液体环境中吸附在不同缺陷体周围的多类型疾病标记物的浓度信息。具体研究基于多缺陷模耦合效应的一维结构；基于中心缺陷模和表面模耦合效应、多频段窄带宽耦合腔光波导的二维结构；基于中心缺陷模和表面局域模耦合的木堆积三维结构等光子晶体器件的生物传感特性。提出研究基于SOI基片的近红外波段硅柱型传感器，背景环境为自由流动的液体，有利于对生物蛋白分子浓度的动态检测。然后利用电子束曝光结合电感耦合等离子刻蚀技术进行传感器件的实验制备，最后利用微区光谱测量系统结合微流控技术进行器件的传感性能测量。

光子晶体传感器主要是基于光子晶体微腔，其品质因子高，模式体积小，能够将光场局域在微腔周围很小的空间内，可以显著增强微腔周围光与物质的相互作用，从而能够反映出微腔周围环境的细微变化。本项目研究团队从光子晶体生物传感器的原理与基本结构出发，研究得出了一维和二维光子晶体波导模和微腔局域模、中心缺陷模与表面局域模、不同缺陷模之间的耦合特性，设计得出了多种结构类型的高灵敏度光子晶体生物传感器件，实现了预期的研究目标。. 基于SOI基片，设计了硅层堆栈型一维结构光子晶体，通过优化参数将两个或多个缺陷体的谐振频率间隔调节为合适的数值；研究得出了宽频段内多个透射谐振峰的频率位置和透过率数值受到背景环境折射率改变区域及折射率改变量等因素影响的规律。. 基于硅柱排列在液体环境中组成的正方晶格和三角晶格二维平板光子晶体，优化设计了入射端和出射端硅柱的形状和尺寸，探索得到了具有良好局域特性的表面模；通过调节中心缺陷体的尺寸参数使得中心缺陷模和表面局域模发生了较强的耦合作用；从而获得了多个局域模的频率位置和透过率具体数值受背景环境参数变化影响的规律。. 通过改变二维八重和十二重准晶结构中心散射柱体的大小，调节了局域模的光场空间分布，实现了光场在低折射率背景区域的强局域；研究了缺陷模波长位置和透过率数值受背景环境折射率细微变化影响的规律，最终获得了高灵敏度浓度探测型和蛋白质特异性吸附型准晶生物探测器。. 在本项目支持下，团队成员取得较为丰硕的成果，发表学术论文25篇，培养研究生5人。