宽调谐和高Q值的单通带微波光子滤波器研究

Single-passband microwave photonic filter overtakes the drawback of the periodic frequency response and has the potential applications in Radio-over-Fiber, novel optoelectronic oscillator (OEO) etc. To overtake the drawbacks of single-passband filter such as tuning range and Q value etc, we propose a novel single-passband filter. It is realized by a novel active cavity consisting of a common fiber bragg grating and a phase-shifted fiber bragg grating, combining the benefits of high Q filter and single-passband filter, and it can increase the Q value of the single-passband filter significantly and break through the limitation of the Q value of single-passband filter. It can realize the wide tunability by incorporating with a tunable laser and fiber bragg gratings with wide bandwidth. The proposed novel filter structure is compact and has the potential for monolithic integration, and it will has a great significance to push forward the application of microwave photonic filter and the development of the novel OEO. Based on the deeply studying the structures and the characteristics of the phase-shifted fiber bragg grating to realize the single-passband filter with wide tunability and high performance, we will detailedly study the ways to enhance the chracteristics of the novel cavity-based filter and the ways to realize the wide tunability of the filter in the case of keeping the shape of frequency response constant. We will realize a single-passband frequency response with a frequency tunability from 1GHz to 40GHz and a Q value over 4000, and we will also realize an OEO with a phase noise of the generated signal of about -130 dBc/Hz at 10 kHz offset from the carrier and a frequency tunability from 1GHz to 40GHz.

单通带微波光子滤波器克服了频率响应周期性的缺点，在光载无线通信和新型光电振荡器等方面具有重要应用。针对目前单通带滤波器在可调谐范围和Q值等关键性能方面的限制，本项目创新性提出了一种新型单通带滤波器。通过普通光纤光栅和相移光纤光栅混合构成新型腔，融合了高Q滤波器和单通带滤波器的优点，可极大提高单通带滤波器的Q值，突破了单通带滤波器在Q值方面的限制。结合可调谐激光器和宽带光纤光栅可实现滤波器的宽调谐。该方案结构紧凑，有实现单片集成的潜力，对推动微波光子滤波器的应用及新型光电振荡器的发展具有重要意义。在深入研究相移光纤光栅结构与特性以实现宽调谐高性能单通带滤波器的基础上，重点研究增强新型腔滤波器性能的方法以及在频响形状不变情况下的宽调谐的实现方法。实现可调谐范围为1-40GHz、Q值大于4000的单通带滤波器。实现相位噪声优于-130dBc/Hz@10kHz、1-40GHz宽调谐的光电振荡器。

单通带微波光子滤波器克服了频率响应周期性的缺点，在光载无线通信和新型光电振荡器等方面具有重要应用。针对目前单通带滤波器在可调谐范围和Q值等性能方面的限制，本项目进行了高Q值单通带滤波器的研究。首先建立了相移光纤光栅(PS-FBG)的理论模型进行了PS-FBG与啁啾PS-FBG结构特性的研究，并进行了基于PS-FBG与啁啾PS-FBG的单通带滤波器的理论与实验研究。进行了基于偏振调制与切趾光纤光栅的单通带滤波器的研究，通过调谐两个可调谐激光源的波长，实现了单通带频率、带宽单独可调，也实现了频率与带宽同时可调，具有很大的灵活性以及潜在的应用。提出了基于Sagnac环与多光源的单通带滤波器，通过调节多光源的波长，可实现频率与带宽的可调。进行了基于锁模光纤激光器的单通带滤波器的研究，调节腔内的两个偏振态，可实现输出光源的光谱分割,也可以实现分割间隔的可调，因而可实现单通带频率可调。进行了基于放大光纤延时环的高Q滤波器的研究，实现了3dB带宽为65.69 kHz，自由谱范围（FSR）为11.58MHz，Q值为176的频率响应，获得了高Q值和陷波相互切换的微波光子滤波器。进行了基于偏振调制的无限冲击响应（IIR）高Q滤波器的研究，实现了高Q滤波器与陷波滤波器的切换；进行了基于PS-FBG的单通带滤波器的研究，实现了可调的单通带以及单陷波滤波器；进行了高Q滤波器与有限冲击响应滤波器的级联研究，实现了级联滤波器的FSR和Q值分别为28.1 MHz和1268，抑制比为30 dB的频率响应。进行了IIR滤波器与IIR滤波器级联的研究，实现了FSR、3dB带宽和Q值分别为174.97 MHz、0.21MHz和833的频率响应。进行了IIR滤波器与单通带滤波器级联的理论研究，理论上实现可调谐范围可以达到96GHz以上，Q值可以达到6400以上的频率响应。进行了基于锁模光纤激光器的单通带滤波器与IIR滤波器的级联实验研究，当单通带与IIR的峰值对准时，可减小单通带的3dB带宽。进行了单通带滤波器的光电振荡器（OEO）的理论与实验研究，通过调节滤波器的频率，可实现OEO的可调。探索了硅基的单通带滤波器的平面波导结构与实现方法。