【作者】 李卫彬；

【导师】 孙军强；

【作者基本信息】 华中科技大学 ， 光电信息工程， 2009， 博士

【摘要】 光学滤波器在波分复用系统中是一类重要的器件。其中，环谐振腔由于具有优良的频率选择特性和能量存储特性，一直被广泛地研究和应用。本文用信号流程图法研究了几类以环谐振腔为基础元件的光学滤波器的特性。全文内容如下：(1)针对马赫-曾德尔(MZI)干涉仪余弦输出的特点，分析了将光纤环谐振腔加入MZI的改进方案。用信号流程图法分析了带阻式光纤环谐振腔对MZI输出谱的影响，用传输矩阵法分析了带通式光纤环谐振腔对MZI输出谱的影响。分析结果表明，这两类器件的输出谱相对于常规MZI来说，都具有更高的0．5dB透过带宽和25 dB截止带宽，输出谱形态是近似于矩形方波的理想梳状谱，降低了对入射信号光的要求。(2)使用两个基本的透射式微环谐振腔，构造了一个级联的复合微环谐振腔结构，分析了该复合谐振腔的输出谱特性。研究结果表明，相对于单个透射式微环谐振腔而言，由于内在的游标效应，级联结构谐振腔输出谱的阶数受到抑制，自由谱宽范围得到了扩展，输出谱的精细度和对比度也得到了显著的提高。(3)提出了一种MZI干涉仪辅助的微环谐振腔结构，利用信号流程图法推导了该器件的输出功率表达式和半峰全宽表达式。进行了数值模拟，结果显示MZI干涉仪辅助的微环谐振腔具有周期性的带阻滤波特性。最后，分析了MZI干涉仪两臂差产生的相位，以及耦合系数对器件输出谱的影响。研究结果对该器件的实际加工和进一步改善其滤波性能都具有重要的参考意义。(4)针对成品相移光栅反射谱中透射窗口位置的不可调谐性，提出了一类由环谐振腔和布拉格光栅组成的新型器件。详细分析了器件的工作原理，给出了器件的反射谱输出表达式，并推导了反射谱的精细度和半峰全宽的表达式，利用matlab进行了数值模拟。结果发现光栅辅助的环谐振腔的反射谱具有相移光栅反射谱的特点，并且该反射谱中透射窗口的个数、深度和位置还具有可调谐性。最后，分析了谐振腔参数对反射谱的半峰全宽和精细度的影响，为进一步提高该器件的性能提供了理论依据。更多还原

【Abstract】 Optical filter in wavelength division multiplexing system is an important class ofdevices. Among them, the optical ring resonators due to their high frequencyselectivity and significant power storage at the resonance frequencies, have beenextensively researched and applied. In this dissertation, several optical filter based onring resonator are analyzed in detail using signal flow graph method. The maincontents of the dissertation are as follows:(1)The Mach-Zehnder interferometer(MZI) has the cosine output characteristics.To solve this problem, a device based on Mach-Zehnder interferometer with a fiberring resonator in one arm is proposed. Using the signal flow graph mehtod, influenceon the MZI interferometer by the stopband type fiber ring resonator is discussed. Andusing the transmission matrix method, the influence on the MZI by the passband typefiber ring resonator is also discussed. The result indicates that the width of 0.5dBpassband and 25dB stopband of proposed devices are simultaneously improvedremarkably, which are much wider than that of the conventional MZI interferometer.The filtering performance of these proposed devices, which achieve a nearly squarespectrum response, are much better than the conventional MZI. Therefore, therequirements of the incident optical signals by these devices are reduced.(2)A compound optical vernier filter with cascaded microring resonators isproposed. The proposed filter consists of two individual passband micoring resonators.Its output characteristics is analyzed. A comparison between this proposed vernierfilter and one individual micoring resonator is made. The simulation results show thatthe contrast and finesse of proposed vernier filter can be increased remarkablycompared to the individual one micoring resonator. And it is found that the freespectral range of proposed filter can be enhanced by the vernier operation.(3)A novel microring resonator based on Mach-Zehnder interferometer isproposed. Its transmission function is theoretically analyzed by using the signal flowgraph method. The expression fot the full width at half maximum of the transmissionspectrum is also derived. Numerical simulations show that transmission spectrum has the periodic narrow stopband filtering characteristic. The influence of phase differencebetween the two arms of MZI and coupling coefficient on the transmission spectrum isalso analyzed. The results, are of very important significance in its actual processingand improvement of filtering characteristic.(4)The transmission window of reflection spectrum for phase-shift gratingproducts is not tunable, To solve this problem, a device with Bragg grating-assistedring resonator is proposed. The mechanism of the device is analyzed in great detail.Meanwhile, analytical expressions of reflectivity and its finesse, full width at halfmaximum are derived. Matlab computation results show that reflection spectrum ofproposed device is similar to that of phase-shift grating. Location and depth oftransmission window are tunable in its reflection spectrum. Influences on its finesseand full width at half maximum by the parameters of ring resonator are also discussed,which provides the theoretical basis for improving its performance as frequencyselective element for a narrow line width of single-frequency fiber laser.更多还原