40-GHz subharmonic optical clock recovery has been demonstrated using an optoelectronic oscillator (OEO) injection locked by 160-Gb/s data streams. The data streams are coupled to a photodetector in the OEO feedback loop after transmitted through a LiNbO₃ intensity modulator, which enhances the residual subharmonic clock component in the data streams. The pulse width and root-mean-square timing jitter of the recovered clocks are 9.03ps and 221fs (10Hz-40MHz), respectively.