【作者】 刘海涛；

【导师】 潘炜；

【作者基本信息】 西南交通大学 ， 通信与信息系统， 2009， 硕士

【摘要】 光纤Bragg光栅是光纤通信和传感领域最重要的器件之一,也是目前学科前沿的课题之一,由于其插入损耗低、对偏振不敏感、与普通光纤接续简便、光谱响应特性动态可控以及结构紧凑、易于集成等特点,被广泛的应用于光通信和光传感的各个环节当中。随着光通信的逐步发展,不仅对光纤Bragg光栅光谱中的谐振波长、峰值和带宽的要求更加严格,在频谱特性分析与改进方面还有大量的工作要做。首先简单阐述了光纤光栅的发展历程,介绍了常见光栅的分类与应用。然后从波动方程出发推导出了适用于光纤Bragg光栅的耦合模方程,介绍了传输矩阵法。接下来对多相移(MPS)理论进行了简单的描述,并运用传输矩阵法对基于MPS的矩形采样、Sinc采样、高斯(Gauss)切趾光栅的频谱特性图进行了数值模拟,对模拟结果做了分析与讨论。最后提出了一种设计宽带平坦多信道梳状滤波器的简单方法,根据实际的DWDM系统需要预定设计目标,针对不同的要求给出设计思路并进行了数值模拟与分析。MPS技术在Sinc采样光栅和Gauss切趾采样光栅中的数值模拟结果表明:Sinc采样光栅带外旁瓣和带内的串扰都会受到折射率变化量的影响,加入多相移之后,扰动就会更加剧烈。Gauss切趾光栅消光比随切趾参数G的增大而增大,加入多相移之后,消光比都会有一定程度的下降;而信道带宽与信道间隔之间的比值会随着G的增大而增加,当加入多相移后,这个比值会更大。对宽带平坦多信道梳状滤波器的设计表明:该滤波器整个反射谱的波段范围很广,信道数目成倍增加,且其平坦性会随着折射率变化量的增大而得到改善,信道反射率很高,反相级联体方法的引入可以对滤波器反射谱的消光比和峰值达到很好的改善。整个设计结果基本满足各项预定的指标要求,对于实际的滤波器应用有一定的参考价值。更多还原

【Abstract】 Optical fiber Bragg grating is one of the most important equipments in fiber communication and sensing system, and is a very advanced project all around the world too. It can be used extensively in almost all the links of optic communication because it has many advantages such as low insertion loss, polarization insensitive, easy connection with fiber, controllable and dynamic, contact construction, easy to integrate etc. With the development of optic communication, not only the requirements for the resonant wavelength of the reflection spectrum, peak value and bandwidth will be stricter, but there is still a great deal of work to do about the spectrum analysis and improvement.Firstly, the development, classification and application of FBG have beensimply illustrated. Secondly, the Coupled-Mode Theory which is fit for the Bragg grating was derived from the wave equation and a simple but effective numerical method known as Transfer Matrix Method is also presented. And then, a very useful theory-Multiple Phase Shifts (MPS) theory is discoursed in detail. The reflection characteristic of rectangle sampled, Sinc sampled, Gauss apodized gratings with MPS have been calculated by using the Transfer Matrix Method, the analyzing and discussion were given in the end. Finally, a method for designing a broad spectrum multi-channel optical filter base on FBG is proposed. It was designed according to the practical demand in DWDM and with many different requirements, and the numerical simulation was shown in the end.The results of MPS theory in Sinc sampled grating and Gauss apodized sampled grating indicate that in Sine sampled gratings, the side-lobes and crossfire must be influenced by the index change. After using the MPS, the crossfire will be more severe. In Gauss apodized gratings, the extinction ratio and the ratio of bandwidth to channel spacing all will be changed with the parameter of G. After using the MPS, the change will be cuter.The designing of a broad spectrum multi-channel optical filter shows that the wave band of the reflection spectrum is widened and the channel number is multiplied. What’s more, the spectrum flatness is improved with the increasing of refraction index change. Moreover, for the sake of improving the extinction ratio and peak value when MPS adopted in concatenated SFBG, an available designing method based on the cascaded unit is put forward and the optimized results are obtained.更多还原