The Theoretical And Experimental Study On Photonic Microwave Filter

Recently, photonic microwave filters (PMFs), which feature high bandwidth, immunity to EMI, light weight, low loss and so on, have attracted more and more interest. PMFs can filter microwave and radio frequency signals directly in optical domain and have become important components in Radio over Fiber (RoF) system. This dissertation concentrates on the study of PMFs from the following three aspects: the design of PMFs using optimization algorithm, the configuration design of PMFs and the application of PMFs in RoF systems.In the first part, the problem of synthesis of FIR photonic microwave filters with linear phase response is addressed and a novel method employing Tabu algorithm is proposed. As an illustration of the proposed method in the application of filter design, the optimization of fiber Bragg grating-based photonic microwave filters is demonstrated. Numerical results confirm the efficiency of the proposed method.In the second part, a new configuration of the flat-top filter is proposed. Two EOMs, which can realize negative tap and simplify the configuration, are used in the flat-top filter for the first time. Besides this, a simple and economical method to realize PMF with multi-taps based on Fabry-Perot (FP) laser is also discussed. The theoretical analysis and the experimental results validate the feasibility of the two proposed designs.In the third part, a photonic microwave filter based on fiber loop and fiber Bragg gratings (FBGs) is applied in Radio over Fiber (RoF) system to suppress the relative intensity noise (RIN) of laser and amplified spontaneous emission (ASE) noise of erbium doped fiber amplified (EDFA). Experiment results show that the signal noise ratio (SNR) of the system can be effectively improved by using such a noise filter in the system.