Research On Photonic Generation Of Microwave And Ultra-wideband Signals In Microwave Photonics

Microwave photonics is a new technique that studies the interaction between microwave and optical fiber communications, which combines the advantages of optical fiber communications and the advantages of the wireless communications, for applications such as broadband wireless access networks, satellite communications, warfare systems, radar and sensor networks. Photonic generation of high quality microwave and ultra-wideband signals are key techniques of microwave photonics systems, and has attracted much more research interests. The main topic of this thesis is the photonic generation of high quality microwave and ultra-wideband signals, we also analyze link performance.In this paper, firstly, we introduce the theoretical model principle of photonic generation of microwave signal, and DSB, SSB and OCS modulation are briefly analyzed. Secondly, we briefly introduce two methods of optical microwave signal generation with high frequency multiplication factor, high quality optical millimeter-wave generation by frequency octupling via two parallel MZ modulators and polarization state rotation filter is proposed. For the2.5Gbit/s OOK signal carried by the60GHz optical mm-wave generated via the scheme, we study the transmission performance of the system, The simulation results show that the generated optical mm-wave signal maintains good performance even after being transmitted over25km standard single-mode fiber. Thirdly, the performance parameters of microwave photonics link is introduced, the methods about how to improve the link performance are analyzed, and the parameters of optical fiber delay line is simulated. Lastly, many techniques is introduced for optical UWB pulse generation, a novel method based on DDMZ modulator to generate ultra-wideband (UWB) monocycle and doublet pulses is analyzed, the performance evaluation of UWB signal transmission over fiber is researched, and optical frequency conversion for millimeter wave Ultra wideband over fiber systems is studied. Theoretical analysis and simulation results show fiber dispersion to affect Ultra-wideband signals after optical frequency conversion is primely restrained, this system realizes photonic generation of Ultra-wideband signals, optical frequency conversion and UWB-over-fiber communications, the system structure is simple and easy to realize, which can be applied widely in the future.