Research Of All-optical Ultra-wideband Signal Source Based On Cross-Gain Modulation In Semiconductor Optical Amplifiers

As an wireless communication method using ultra-short pulses to transmit information,ultra-wideband (UWB) has good anti-jamming performance, high transfer rate, great securityfeatures, low transmit power and many other advantages. As a result, people have pay more andmore attention on the research of UWB technology since the civilian of the UWB technology hasbeen approved by the United States-Federal Communication Commission (FCC) in 2002. TheUWB over Fiber technology is proposed because of the fairly short transmission distance of UWBradio technology, which is the result of the quite low transmit power of UWB signals. UWB-over-Fiber not only can extend the effective transmission distance of UWB signals effectively, but alsomerge with the current optical networks perfectly, therefore, it is one of the most promising wirelessaccess technology. All-optical UWB signals source is one of the key technologies achievingUWB-over-Fiber. In this thesis, several all-optical UWB signal source technology based oncross-gain modulation (XGM) in semiconductor optical amplifier (SOA), which have simplestructure, good performance, are presented. The research and analysis of the several schemes arealso carried out in this paper. The main achievements and conclusions are listed as follows:(1) The development history of UWB technology is clarified. The type and configuration ofall-optical generation and modulation of UWB signal technology are summarized.(2) The theoretical foundation of SOA is introduced. The basic equations in SOA are derivedand various nonlinear effects are introduced. The numerical model of SOA used in this paper basedon the common models is presented.(3) A new scheme for achieving UWB monocycle pulse based on XGM in SOA is presented.By numerical simulation, the impact of source power and its wavelength, injection current, thewidth of input pulse on the output monocycle pulse are investigated. After the improvement of thescheme, the impact of source wavelength on the achieved two kinds of monocycle pulses arestudied.(4) A new scheme for achieving all-optical UWB doublet signal based on XGM in SOA isreported. By simulation, the impact of source power and its wavelength, the injection current, thewidth of input pulse and other system parameters on the output doublet pulse are analyzed.(5) A new scheme for achieving all-optical UWB PAM based on XGM in SOA is proposed. Bysimulation, using the eye diagram analysis method, the impact of source power, injection currentand its wavelength on the spectral characteristics, clock extraction, symbol judgment of UWB PAMsignal.