Filter-free all-optical UWB monocycle generation based on the semiconductor optical amplifier (SOA) nonlinearities

A filter-free all-optical pump-probe scheme for ultrawideband (UWB) monocycle pulse generation with single semiconductor optical amplifier (SOA) is proposed and demonstrated. A pair of polarity-reversed optical pulses is generated due to cross gain modulation (XGM) in the pump-probe scheme, whereas the amplified pump pulse becomes sharp in its leading edge such that the power peak is shifted forward. Hence, the combination of the pump and probe signals at the SOA output is directly monocycle-like. Our scheme is an novel scheme without optical filters and time-delay devices. The generated UWB radio frequency spectrum shows good stability when the input probe power varies from -10 dBm to 6 dBm, the probe wavelength varies in the whole C-band, and the bias current varies from 100 mA to 240 mA.