A novel optical ultra-wide band(UWB) pulse generator is proposed and experimentally demonstrated in this paper.Two complement phase-modulated signals will be generated at the output of the polarization modulator(PolM),when a Gauss signal is applied to the PolM.After that,a Gauss signal or a second-order Gauss signal will be generated at the output of the polarization beam splitter(PBS) based on phase modulation to intensity modulation,and under different phase shifts introduced by the polarization controller.The signals from PBS are inversed.So when the Gauss and second-order Gauss pulses are with relative delay to each other and then combined at the output of polarization beam combiner(PBC),Gauss monocycle or third-order Gauss signal will be generated.Since optical signals with different optical spectra would have different tolerances to fiber dispersion,the transmission performances of the three types of UWB signals are also studied.