Study On The Application Of Fiber Bragg Grating In Microwave Signal Processing

Recently, microwave and millimeter-wave signal processing using photonic components, a branch of microwave photonics, has received much attention. This photonic signal processing method has many advantages, such as high time-bandwidth products, overcoming the electrical bottlenecks, high isolation, high compatibility with electromagnetic environments, etc. It can be used in ultra-wideband wireless mobile communications, phased-array radar and microwave/millimeter-wave signal processing. Fiber Bragg gratings (FBG) provide a novel and flexible method to process microwave signals. In this thesis, the applications of FBGs in microwave signal processing are studied.Firstly, the applications of FBG in microwave signal processing are reviewed. We theoretically analyze the operation principle of photonic microwave filter employing FBGs, and summarize the filter design methods in time domain and in frequency domain. The tabu search algorithm is especially employed to design the photonic microwave filter with linear phase response and nonlinear phase response, and the structure based on FBGs to realize the transfer function is proposed. Secondly, the recirculating microwave notch filter is theoretically studied with the analysis method of signal flow chart and the performance of the filter is investigated experimentally. In the experiment, the tunability of filter could be realized by changing the input light wavelength, and the effect of optical source coherence length on the performance of incoherent photonic microwave filter is especially researched. By comparing the theoretical results and experimental results, we find the requirements for constructing a stable filter in the experiment. Thirdly, a novel harmonics suppressed microwave transversal filter with multiple taps based on FBGs, and a novel microwave filter with flat-top passband response are proposed. They are both theoretically analyzed and investigated experimentally to prove the feasibility. Furthermore, the applications of FBG in microwave signal processor, such as, photonic generation microwave signal and microwave shifter, are studied theoretically and discussed.In conclusion, the research on the application of FBG in microwave signal processing in this thesis will be conducive to the application of FBG in microwave photonics.