IR-UWB-Over-Fiber Systems Compatible With WDM-PON Networks

Integrating an ultrawideband-over-fiber (UWBoF) system into a wavelength division multiplexing passive optical network (WDM-PON) is of great interest due to the high potential to provide high data-rate and flexible wired and wireless services with a favorable cost. In this paper, we perform a comprehensive study on an impulse radio UWBoF system compatible with the WDM-PON architecture implemented based on a photonic microwave bandpass filter. The bandpass filter is a two-tap delay-line filter implemented using either a polarization modulator (PolM) or a phase modulator (PM), which is used to simultaneously shape an electrical Gaussian-like pulse to an optical UWB pulse and reduce the out-band noise and interference. The features of the photonic microwave bandpass filters are theoretically studied. The photonic microwave bandpass filter based on a PolM would produce a chirp-free UWB signal, while the one based on a PM would generate a UWB signal that is insensitive to fiber dispersion. A single-channel UWBoF system with ON-OFF keying, biphase modulation, and pulse-position modulation without and with time hopping are experimentally studied. The experimental results agree well with the theoretical predictions. A four-channel UWBoF broadcasting network as well as a hybrid WDM-PON network to provide both wireless and wired services is also experimentally investigated. Results show that a conventional WDM-PON network could be easily upgraded to provide UWB services by incorporating the proposed photonic microwave bandpass filter.