In this paper, a novel method to generate both monocycle and doublet UWB pulses is demonstrated, where pulse shape
modulation(PSM) can be easily implemented. Only two wavelengths and two modulators (one dual-in dual-out
modulator) are applied to achieve PSM. The data driving the first modulator is set to be 250Mbit/s 107-1 pseudo-random
bit sequence (PRBS). The 1GHz pulse pattern is synchronised with the data. The electrical spectrum of the signals
processes the centre frequency of 4GHz and -10dB bandwidth of 5.9GHz. The fractional bandwidth is about 147.5%,
which matches the FCC standard.