We experimentally demonstrate all-fiber optical Manchester code generation at 10 Gbit/s using nonlinear polarization rotation in a single 1- km highly-nonlinear fiber with the nonlinearity of 20.4 W-1km-1. 33-dB extinction ratio is achieved in a -4-dBm CW dummy channel by coinjecting orthogonally aligned two 8-dBm pumps into the Kerr medium. Our encoder functions with 10 Gbit/s NRZ data stream and 10 GHz optical clock as the pumps. We present the resultant waveform as well as the optical spectrum of the Manchester-coded output.