Filter-free ultra-wideband doublet pulses generation based on wavelength conversion and fiber dispersion effect

Abstract

Filter-free ultra-wideband (UWB) doublet pulse generation is experimentally demonstrated in the optical domain based on cross-gain modulation (XGM) in semiconductor optical amplifier (SOA) and UWB-over-fiber technology is implemented by exploiting dispersion-induced pulse broadening effect in single-mode fiber (SMF). In our proposed system, the SOA generates a polarity-inversed Gaussian pulse train with respect to the injected one through the XGM. After a piece of SMF, the bandwidth of polarity-reversed Gaussian pulse broadens due to the induced dispersion. After the combination of the two light waves with a suitable time delay between them, UWB pulse is obtained. The key parameters for UWB pulse, including central frequency, 10dB bandwidth, as well as fractional bandwidth are experimentally obtained with 8GHz, 9.9GHz and 123% respectively. The generated UWB doublet pulse conforms with the UWB definition of Federal Communications Commission (FCC).