阵列波导光栅平坦化的研究

Flat Spectral Response of Arrayed Waveguide Grating

阵列波导光栅的平坦化在实际应用中有很重要的意义.本文系统地研究了阵列波导光栅的平坦化.在输入波导、输出波导、阵列波导输入端与输出端上分别引入了指数型锥形波导.通过改变锥形波导的形状和尺寸来实现平坦化的优化.本文首先从理论上论述了引入指数型锥形波导的输出光谱特性,给出了结构参量的关系表达式,阐明了输入波导处的锥形波导是影响输出光谱平坦化的主要因素,阵列波导和输出波导处的锥形波导对输出光谱的平坦化有一定的影响.其次采用数值模拟的方法模拟了输出光谱,优化了结构参量,总结出了指数型锥形波导对平坦化影响的趋势和规律.模拟结果显示,输出光谱1dB带宽大于通道间隔的50%,插入损耗从5.2dB减小到了4.0dB,串扰小于-30dB.最后,本文给出了实验结果,插入损耗减小了0.87dB,串扰减小了3.67dB,1dB带宽增加0.1nm,增加了54.7%.实验结果表明引入指数型锥形波导提高了阵列波导光栅器件的光谱性能.

It is significant of the flat spectral response arrayed waveguide grating in practical application. Flat spectral response arrayed waveguide grating is systematically studied. Tapers with exponential type are introduced into input waveguides, output waveguides and arrayed waveguides. Optimal design is achieved by changing the shape and size of the tapers. Firstly, the output spectral characteristic is discussed theoretically for tapers with exponential type and the relational expressions of the structural parameters are given. It is illustrated that the characteristic of the tapered input waveguides is the main factor that affects the output spectrum and that the tapered arrayed waveguides and the tapered output waveguides have a certain impact on the output spectrum. Secondly, numerical simulation method is used to simulate the output spectrum and to optimize the structure. Trend and regularity about flat spectral response affected by the structure of tapers are concluded. Simulation results show that the 1 dB passband width isbigger than 50~ of the channel spacing, Insertion loss decreases from 5.2 to 4.0 dB, crosstalk is less than -30 dB. Finally, the experimental results are given, insertion loss reduces 0.87 dB, crosstalk decreases 3.67 dB, and 1 dB bandwidth increases 0.1 nm with an increase of 54.7%. Experimental results show that the introduction of tapered waveguides with the exponential type improves the spectral properties of the arrayed waveguide grating device.