A novel scheme is proposed for wavelength conversion based on cross-gain modulation (XGM) in a single-portcoupled semiconductor optical amplifier (SOA), in which the input and output share one port. Experimental results and theoretical analysis show that this scheme can be achieved with simple implementation, high output extinction ratio and large input dynamic range. Based on this novel scheme, 2.5 Gbit/s wavelength up conversion with a 12.8 nm span has been demonstrated with the output extinction ratio as high as 15 dB.