We experimentally demonstrate all-optical clock recovery for 100 Gb/s return-to-zero on–off keying signals based on a monolithic dual-mode distributed Bragg reflector (DBR) laser, which can realize both mode spacing and wavelength tuning. By using a coherent injection locking scheme, a 100 GHz optical clock can be recovered with a timing jitter of 530 fs, which is derived by an optical sampling oscilloscope from both the phase noise and the power fluctuation. Furthermore, for degraded injection signals with an optical signal-to-noise ratio as low as 4.1 dB and a 25 km long distance transmission, good-quality optical clocks are all successfully recovered.