光学微环生物传感器的设计与优化.doc

光学微环生物传感器的设计与优化


摘  要
　　　微环谐振腔具有高品质因数、低成本的特点。由于它基于平面波导结构，因而易于同其它光电芯片和微流控芯片集成，并且进行化学表面处理。另外，谐振效应的引入能够在提高灵敏度的同时大大缩小器件的尺寸，所以基于微环谐振腔的生物传感器是一种高灵敏度的，可对微量生物物质进行探测的传感器。本文在国家自然科学基金的资助下，对微环生物传感器的理论模型和性能参数做了系统性的分析研究，完成的主要工作有以下几点：
　　　(1) 基于模式耦合理论和时域有限差分法，深入研究直波导与弯曲波导的耦合性质，并在此基础上建立微环谐振腔的理论模型，得到器件的主要参数如自由频谱区间FSR和品质因数Q的表达式；
　　　(2) 根据微环传感器的工作原理，将总灵敏度分为波导灵敏度和器件灵敏度，着重分析器件灵敏度与传输因子σ、自耦合因子t、以及工作波长λ的关系，并结合上述参数与其他结构参数的关系，提出具体的设计和优化方案；
　　　(3) 利用高斯函数对原洛伦兹响应谱的近似，得到器件品质因数Q与器件灵敏度的关系，从而推出基于品质因数和系统信噪比(SNR)求得探测极限的理论方法，该法对以监测强度变化为工作原理的微环传感器普遍适用；
　　　(4) 推出在具有相位噪声的非理想光源激励下的器件响应总谱，进而得出具有不同线宽的激光光源对微环性能影响的关系式。
　　　
　　　关键词：生物传感器   微环谐振腔   灵敏度分析   探测极限 
Abstract
　　　Due to the compatibility with standard CMOS platform, planar microring resonator with high quality factor can be fabricated at low cost. Based on planar waveguides, it not only allows surface chemical modifications, but can also be integrated with other optoelectronic devices and microfluidic handling, leading to highly integrated and intelligent sensing chips. Furthermore, it offers a unique advantage of reducing the device size without sacrificing the sensitivity by virtue of the resonance. Therefore, micoring resonator biosensor is highly sensitive that can detect minute amount of analytes. Supported by the National Science Foundation of China, the theoretical model and sensitivity are systematically studied in this thesis. The main contents are listed as follows:
　　　(1) The coupling property of the bent-straight coupler is thoroughly investigated, based on coupled mode theory and FDTD method. Theoretical method is established, from which expressions of key parameters such as FSR and Q factor are derived.
　　　(2) The overall sensitivity of the device is divided into two contributions: waveguide sensitivity and device sensitivity. The relations of device sensitivity and transmission coefficient σ, self coupling coefficient t, and operating wavelength λ are studied, based on which a design and optimization guideline is summarized.
　　　(3) By approximating the original Lorentzian lineshape with a Gaussian function, an explicit relation between the quality factor and the device sensitivity is studied. The detection limit is thereafter derived through the quality factor and signal-to-noise ratio (SNR), which is in good agreement with experimental results and universal for microring resonator sensors based on intensity variation.
　　　(4) The overall response is derived, with the phase noise of laser source taken into account. The influence of laser linewidth on the overall performance is studied.
　　　
　　　Keywords: biosensor    microring resonator   sensitivity analysis
　　　　　　　　detection limit
目  录
摘  要 I
Abstract II
1  绪论
1.1  引言 (1)
1.2  微环谐振腔发展简述 (2)
1.3  微环谐振腔的应用 (3)
1.4  微环谐振腔的分类 (3)
1.5  本文的工作 (5)
2  光学微环理论基础
2.1  引言 (7)
2.2  直-弯波导耦合器 (7)
2.3  单直波导耦合微环模型 (18)
2.4  双直波导耦合微环模型 (21)
3  微环传感器灵敏度分析及优化设计
3.1  引言 (25)
3.2  微环传感器的工作原理 (25)
3.3  传感性能的衡量指标 (26)
3.4  灵敏度分析 (27)
3.5  微环传感器的优化设计 (35)
4  微环传感器的探测极限
4.1  引言 (38)
4.2  探测极限 (39)
5  激光器随机相位噪声的影响
5.1  引言 (46)
5.2  具有相位噪声的非理想激光器输出谱 (46)
5.3  非理想激光器对微环的影响 (47)
6  总结与展望 (51)
致  谢 (52)
参考文献 (53)