Ultrawideband (UWB) technology has attracted great interest recently in short-range high-speed wireless communication systems due to its inherent properties such as high data rate, low power consumption and immunity to multipath fading. As required by the Federal Communication Commission (FCC), UWB signals should have a fractional bandwidth more than 20% or a -10 dB bandwidth at least 500 MHz in the frequency range from 3.1 GHz to 10.6 GHz with an effective isotropic radiated power (EIRP) less than -41.3 dBm/MHz. The low emission power limits its transmission distance to tens of meters. To offer availability of undisrupted service across different networks and to eventually achieve high data rate access at any time and from any place, UWB over fiber (UWBoF), which combines the advantages of low loss in the fiber and high data rate of UWB signals, may provide a promising solution.

Conventionally, UWB signals, usually Gaussian monocycle or doublet pulse, are generated using electronic circuits. However, to implement UWBoF, it is a better choice to generate UWB signals directly in the optical domain since there is no need for extra electrical-to-optical conversion. One method of generating UWB signals was to construct a photonic microwave delay-line filter using a semiconductor optical amplifier (SOA) or a polarization modulator (PolM) assisted with a length of polarization-maintaining fiber (PMF). Another method was based on phase modulation to intensity modulation conversion by using a phase modulator (PM) and a Fiber Bragg Grating (FBG) as a frequency discriminator. It was also reported that UWB signals could be generated by using optical spectral shaping and frequency-to-time mapping technique either by using a spatial light modulator (SLM) and a Fourier lens in the free space, or by using all-fiber components. Recently, we have proposed the generation of UWB monocycle and doublet pulse using OPA in two different experimental setup, a repetition rate of up to 4.2 GHz has been achieved so far.