Photonic generation of chirp-free UWB signals for UWB over fiber applications

Highly chirped optical UWB pulses with wide optical spectral widths tend to be distorted by fiber dispersion, which is undesirable for UWB over fiber transmission systems. In this paper, we investigate theoretically and experimentally a method to generate in the optical domain stable chirp-free UWB signals with a narrow optical spectral width. The UWB pulse generator consists of a polarization modulator (PolM) and a polarization-maintaining fiber (PMF) based delay line. The generated UWB signals are transmitted over a 10- or 24-km optical standard single-mode fiber followed by a wireless link. Experimental results show that the system has a good tolerance to fiber dispersion.