Novel Microwave Photonic Filters And Its Application

Microwave photonics is a new interdisciplinary research area, which mainly studies the generation and processing of microwave signals in the optical domain. With the use of modern optoelectronic devices, optical generation and processing of microwave signals show a lot of advantages, such as large bandwidth, good tunability and the immunity to the electromagnetic interference, as well as the compatibility with the modern optical fiber communication systems. Microwave photonics technology has shown good application potentials in high-speed fiber communication systems and modern radar signal processing, etc. Especially, novel microwave photonic filters (MPFs) and their applications has attracted lots of research attention in the past few decades.In this thesis, we have theoretically and experimentally studied the novel incoherent microwave photonics filters based on fiber ring structure and sliced broadband optical source (BOS), respectively. In addition, we have explored applications of these two novel MPFs. The main innovations of this thesis can be classified as follows:1. We have studied the basic structure and principles of the fiber ring microwave photonics filter (FRMPF) theoretically and experimentally. In order to improve the performance of the FRMPF, we have proposed and experimentally demonstrated a FRMPF incorporating a fiber reflector mirror.2. Microwave multiplication scheme based on external modulation and cascade FRMPFs have been proposed and experimental verified. Due to the nonlinear effects of the Mach-Zender modulator (MZM), high order harmonics could be generated when the MZM is driven with a high power microwave signal. By eliminating the low frequency harmonics with cascaded FRMPFs, microwave multiplication could be realized.3. Detailed study of the principles and characteristics of the single-band bandpass microwave photonics filter (MPF) based on sliced spectrum using fiber Mach-Zender interferometer (FMZI) and fiber delay lines has been carried out. An approach of microwave frequency measurement based on the single passband microwave photonic filter has been proposed and experimentally demonstrated. The experimental results show that it enjoys a high precision in microwave frequency measurement.4. A dual-passband MPF based on an FMZI and dual path fiber delay lines has been proposed and experimentally verified. The experimental results show that it has a dual-passband performance with good tunability, and the centre frequency of each passband could be tuned by adjusting the length of the corresponding fiber delay line.5. A novel dual-passband MPF with independently tunable passbands has been proposed and experimentally demonstrated based on two parallel FMZIs and fiber delay line. The experimental results have shown that the present MPF has a dual-passband characteristics and each passband can be tuned freewill by adjusting the length differences of corresponding FMZI.