Photonic generation of UWB pulses with pulse position modulation

A novel photonic approach to generating ultra-wideband (UWB) signals with pulse position modulation (PPM) is proposed. The proposed system consists of two subsystems, the first subsystem being a two-tap photonic microwave delay-line filter for UWB monocycle pulse generation, the second subsystem being a pulse-position-modulation module to achieve PPM. When a Gaussian pulse train is inputted to the first subsystem, a monocycle pulse train is generated. The PPM is then realised in the second subsystem by modulating the state of polarisation of the monocycle pulse train with a data sequence, which is then sent to a polarisation-dependent device to introduce a time delay difference. An UWB signal with PPM at a bit rate of 625 Mbit/s is experimentally generated.