a novel local oscillator (LO)-free frequency mixing based on FP-LD injection is proposed. The sideband of four wave mixing (FWM) between external injection light and one longitudinal mode of FP-LD generates sideband locking longitudinal mode which then produces the radio-frequency (RF) signal. By adjusting the intensity and polarization of injection signal, different mixing frequency is obtained and the different side-mode suppression ratio is analyzed theoretically. Subcarrier of 16.2, 10.0, 18.2 and 20.0 GHz is obtained from 2.7, 2.5 and 1.25 Gb/s NRZ signal injection into FP-LD respectively, in which the single sideband phase noise of -81.2 and -87.7 dBc/Hz at 10 kHz frequency deviation of 16.2 GHz is measured.