We demonstrate an all-optical single to multi-wavelength converter using gain modulation in a Fabry-Perot laser diode (FP-LD at 10Gb/s. It can simultaneously provide 1 to 4 output channels and support both up and down conversion. We observed over 14dB extinction ration (ER) and power penalty of around 1.5dBm at a BER of 10^-9. The results ensure to increase the number of output channels. The proposed scheme can be applied to multicasting function as well as 1xN wavelength conversion in wavelength division multiplexed optical networks.