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摘要
光纤光栅是一种新兴的光子器件。从第一根光纤光栅写制成功到今天短短二
十多年间,光纤光栅无论是写入技术、理论研究还是应用方面都获得了飞速发展。
光纤光栅是利用石英光纤的紫外光敏特性将光栅直接做在光纤上而形成的无
源光子器件,它具有插入损耗低、体积小、成本低、对偏振不敏感、与普通光纤
连接简单等优点,并且可以通过调制光栅的一些物理参数而得到所需要的光谱特
性和时延特性。随着光纤光栅制造技术的不断完善,光纤光栅已成为目前最具有
发展前途,最具有代表性的光纤无源器件之一,被广泛的应用于光纤通信和光纤
传感领域中,近年来,光纤光栅也被用在光控相控阵雷达技术中作为光波的时延
器件。因此,设计符合系统时延特性光纤光栅的研究具有重要的实际意义。
本文首先详细介绍了光纤光栅的发展、光敏特性、分类、制作,在光纤通信
和光纤传感中的应用以及其在光控相控阵雷达中的应用。然后由光纤中的麦克斯
韦方程组出发,严格推导出描述模式耦合的耦合模方程,并用耦合模理论对均匀
布拉格光纤光栅进行分析,建立其耦合模方程,并给出解析解。给出了分析非均
匀光纤光栅的传输矩阵法。
其次,在耦合模理论的基础上,结合传输矩阵法,利用matlab 编程数值模拟
了均匀光纤光栅、啁啾光纤光栅和变迹光纤光栅的光学特性,着重研究了光纤光
栅长度、周期、啁啾、折射率调制和变迹函数对其反射谱谱宽、反射率峰值、时
延特性的影响,为设计合适的光纤光栅器件奠定了理论基础。
最后,提出了利用遗传算法对光纤光栅进行参数重构的方法。以光纤光栅的
参数作为计算个体,反射谱或者时延曲线作为目标函数,经过若干代遗传,重构
出满足目标函数的最优个体,即能够产生所需反射谱或者时延特性的光纤光栅参
数。
关键词:光纤光栅,耦合模理论,传输矩阵法,遗传算法,参数重构
II
ABSTRACT
Fiber gratings are kinds of new photonic devices. Not only fabrication methods
but also concerned theories and applications about fiber grating have been made great
progress, from essful fabrication of the first fiber grating to now.
Fiber gratings, which are one of passive photonic devices written by ultraviolet
light into the core of a photosensitive fiber, have several distinguished advantages,
such as: low insertion loss, small bulk, potentially low cost, insensitive to polarization,
and simply spliced into fiber systems. Desired spectral properties or time-delay
characteristics can be achieved by changing physical parameters of fiber gratings. With
its improvement in fabricating technology, fiber gratings have e one of the most
promising and representative passive optical fiber devices, which have wide
applications in optical munications and optical fiber sensing fields. Recently,
fiber gratings are used as time-delay devices in optically controlled phased array
antennas. Therefore, it is very important to design fiber gratings that meet specific
time-delay characteristics from the viewpoint of practical applications.
In this paper, we firstly introduce the develo