Research On Ultra-wideband Pulse Processing Technology Using Optical Loop Mirror

Ultra-wideband (UWB) communication is a novel wireless communication techniqueusing ultra-short pulse as the signal carrier. According to the regulation of the U.S. FederalCommunication Commission (FCC), a UWB signal has a10dB bandwidth larger than500MHz or a fractional bandwidth greater than20%with a power spectral density no more than-41.3dBm/MHz. FCC also regulated7.5GHz frequency band from3.1GHz to10.6GHz forunlicensed use of UWB. The UWB communication has advantages of high propagation datarate, huge communication capacity, low power consumption, simple structure andexceptional multipath immunity. However, the restriction of the maximum transmissionpower spectrum density limits the operating range to less than tens of meters.UWB-over-fiber system is proposed and regarded as a promise solution to increase thepropagation distance of UWB signal.In this thesis, several studies of photonics UWB pulse processing technology especiallyincluding UWB pulse generation and modulation have been presented as follow(1) The characteristics of photonics UWB pulse have been analyzed. Considering ofthe cost of UWB-over-fiber system and the electrical spectra of the UWB pulse, the first-tofourth-order derivatives of Gaussian pulse have been regarded as the best type photonicsUWB pulse. Varied with the increase of the order of the derivative, the10dB bandwidth ofthe pulse has been broadened and the spectra power efficiency has been increased.(2) Five novel schemes of optical loop mirrors are proposed. These schemes are alsotheoretically and experimentally demonstrated the ability of UWB pulse generation.Furthermore, a UWB pulse with a10dB bandwidth of10.8GHz is theoretically gained andanother with a10dB bandwidth of12.5GH is experimentally generated at same time.(3) A novel optical nonlinear loop mirror with dual pump light is proposed. Based onthis structure, pulse amplitude modulation, pulse bi-polar modulation, pulse shapemodulation and code division multiple access modulation of UWB pulse are realized.