基于U型波导耦合单微环结构的光学传感理论与应用研究

发布时间：2018-11-03 18:33

【摘要】：光学微环谐振器的概念和结构自1969年由Marcatili提出以来,以其体积小、损耗低、高Q值、高灵敏度、易于集成等诸多优点,在光学通信、信息处理和传感等不同领域引起了广泛关注。经过30多年理论和实验上的深入研究,不论是在特殊应用领域,还是在多样性的材料选择及其性能改善上都取得了很大程度的发展。传统的传感器具有体积偏大、集成度低、结构复杂、测量范围有限、灵敏度低等缺点,在很多应用领域表现出一定的局限性。近年来,传感器正处于由传统型向新型传感器转型的发展阶段,许多新颖传感器逐渐出现,微环传感器就是具有代表性的一种,基于不同结构、材料和应用领域的微环传感器在理论和实践上都得到了广泛的研究。本文提出了基于U型波导耦合单微环结构的光学传感理论与应用研究,并通过理论仿真获得了较高的灵敏度和大的测量范围,本文主要工作为:首先,阐述了微环传感器的研究意义,并以近期报道出来的具有代表性的微环加速度传感器、温度传感器以及生物化学传感器为例,详细介绍了微环传感器的研究现状,重点分析了微环结构紧凑,集成度高、微型化、灵敏度高等特点。其次,以光波导和耦合模理论为基础,介绍了微环谐振器基本的研究方法—传输矩阵法,并详细介绍了微环的基本原理、主要的性能参数、数学模型以及制造工艺,并采用U型波导耦合单微环结构作为光学传感器的数学模型,通过传输矩阵法分析了其传输特性,并分别讨论了耦合系数、损耗、波导有效折射率、微环半径以及U型波导两个耦合点之间的间距对于输出光谱的影响,为此类光学传感应用研究与设计提供了理论基础。最后,对基于U型波导耦合单微环结构的湿度传感器及温度传感器进行传感特性分析。湿度传感器采用聚酰亚胺为感湿介质,基本原理为:相对湿度的变化引起输出光谱的漂移,并讨论了最佳感湿部位的选择方案,通过仿真发现其灵敏度比传统的湿度传感器有了大幅度提高,并分析了抑制温度干扰的措施;温度传感器采用SOI为材料,基本原理为:温度的变化引起有效折射率变化,导致输出光谱漂移。通过仿真发现其测量范围近似为传统单微环温度传感器的两倍,但仍较小,进而采取减小半径的方式进一步增大了温度测量范围,但会增加弯曲损耗,因此分析了减小弯曲损耗的方法。
[Abstract]:The concept and structure of optical microring resonator have been proposed by Marcatili since 1969. It has many advantages such as small volume, low loss, high Q value, high sensitivity, easy integration and so on. Various fields such as information processing and sensing have attracted wide attention. After more than 30 years of theoretical and experimental research, a great deal of progress has been made in the field of special applications, in the selection of diverse materials and in the improvement of their properties. Traditional sensors have the disadvantages of large volume, low integration, complex structure, limited range of measurement, low sensitivity, and so on, so they have some limitations in many application fields. In recent years, the sensor is in the transition from the traditional type to the new type of sensor. Many novel sensors are emerging gradually. The microloop sensor is a representative one, based on different structures. Microloop sensors in materials and applications have been widely studied in theory and practice. In this paper, the theory and application of optical sensing based on U-shaped waveguide coupled single microloop structure are proposed, and the high sensitivity and wide measurement range are obtained by theoretical simulation. The main work of this paper is as follows: first of all, The research significance of microloop sensor is expounded, and the research status of microloop sensor is introduced in detail, taking the typical microloop accelerometer, temperature sensor and biochemistry sensor as examples. The characteristics of compact structure, high integration, miniaturization and high sensitivity are analyzed. Secondly, based on the theory of optical waveguide and coupling mode, the basic research method of microring resonator, the transmission matrix method, is introduced, and the basic principle, main performance parameters, mathematical model and manufacturing process of microloop are introduced in detail. Using the U-shaped waveguide coupled single microloop structure as the mathematical model of the optical sensor, the transmission characteristics are analyzed by the transmission matrix method, and the coupling coefficient, the loss and the effective refractive index of the waveguide are discussed, respectively. The influence of the radius of the microloop and the spacing between the two coupling points of the U-shaped waveguide on the output spectrum provides a theoretical basis for the application and design of this kind of optical sensor. Finally, the characteristics of humidity sensor and temperature sensor based on U-waveguide coupled single microloop structure are analyzed. The humidity sensor adopts polyimide as humidity sensitive medium. The basic principle is that the change of relative humidity causes the drift of output spectrum. The simulation results show that the sensitivity of the sensor is much higher than that of the traditional humidity sensor, and the measures to suppress the temperature interference are analyzed. The temperature sensor uses SOI as the material. The basic principle is that the change of temperature causes the change of effective refractive index and the output spectrum drift. It is found by simulation that the measurement range is approximately twice as large as that of the traditional single microloop temperature sensor, but is still small. By reducing the radius, the temperature measurement range is further enlarged, but the bending loss is increased. Therefore, the methods to reduce the bending loss are analyzed.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN629.1

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