【作者】 李志雄；

【导师】 何对燕；

【作者基本信息】 武汉大学 ， 光学工程， 2004， 硕士

【摘要】 在波分复用系统中，基于平面波导技术制作的阵列波导光栅正起着越来越重要的作用，它提供了一种新的解决通信网络中系统的传输容量和灵活性问题的方案。不过随着波分复用通道数的增加，传统的阵列波导光栅对光源的光谱分布和器件温度漂移不敏感性要求比较高，平坦谱响应的AWG(Arrayed Waveguide Grating)则可以放宽对上述性能的要求。 本文全面介绍了阵列波导光栅波分复用器的基本原理和结构，详细地阐述了AWG的各个性能评价指标，并分析总结了提高这些性能指标的各种方法。为了获得平坦响应的通带宽度，在输入波导末端插入一个多模干涉仪，这样通带宽度得到一定的展宽。不过上述方法往往会导致插入损耗和带通纹波的恶化。本文在此基础上改进多模干涉仪的结构参数，将其设计为抛物线型，通过优化其另一端的宽度和干涉仪的长度，可以减小通带纹波。同时，在多模干涉仪前置一个锥形波导，来对多模干涉仪的输入场进行调整，使其更陡峭，这样也将有助于获得更平坦的带宽。此外，考虑到输入波导弯曲导致的光场峰值偏离波导中心，一细直波导被用来减小由此导致的场型畸变。 按照上述优化过程设计出了一个改进的阵列波导光栅，并采用广角束传播法对其进行了数值计算，改进的AWG的1dB有效带宽可达64％，3dB有效带宽可达78.8％，通道串扰优于-30dB，插入损耗可以维持在-4.35dB到-5.0dB之间。更多还原

【Abstract】 Arrayed waveguide grating (AWG) is playing an increasingly important role in dense wavelength division multiplexing (DWDM) system. AWG provides a new dimension for solving capacity and flexibility problems in the telecommunication network. However, with the increase of channels, the conventional AWG requires better spectrum of lasers and insensitivity to the wavelength shift, the AWG with flattened passband can broaden these requirements.In the present thesis, the principle and structure of arrayed waveguide grating are introduced, the characteristic parameters of AWG are expatiated, and some methods that improve these characteristic parameters are analyzed and given. In order to obtain flatten passband, a multimode interferometer (MMI) is used to flatten the bandwidth of AWG and connected at the end of the input waveguide. However it results in larger ripple and deterioration of the on-chip insertion loss of AWG. So the present paper presents the following improved methods. A parabolic shape MMI is applied, and the ripple can be reduced by optimizing the width and length of the parabolic MMI. Moreover, a tapered waveguide is connected before the MMI, which reshapes the input field of MMI and decreases the loss resulting from mismatch of mode fields. Furthermore, a straight waveguide is added before the tapered waveguide to decrease distortion in mode fields, which results from the off centering of the peak field because of the bend of the input waveguides.According to the solution presented above, a novel AWG is implemented. Wide-angle beam propagation method (BPM) is used to simulate the improved layout. The ldB bandwidth of 64% and 3dB bandwidth of 78.8% are obtained for the 1000GHz channel spacing. Crosstalks to neighboring and all other channels are less than -30dB and the on-chip insertion losses range from -4.35dB to -5.0dB respectively.更多还原