A novel 10 Gbit/s all-optical packet clock extraction is proposed, which comprises a Fabry-Pérot (F-P) filter and a semiconductor optical amplifier (SOA). Low finesse Fabry-Pérot filter was used to directly extract the packet clock from the data packet which ensures that the clock locks fast and vanishes quickly. The clock, amplitude modulated as a result of low-Q filter, then goes into SOA to reduce the low-frequency amplitude noise. The effect of the SOA's SGM on the locking and unlocking time of the packet clock is theoretically analyzed. Instantaneous 10.075 GHz clock extraction experimentally with the establishing time of about 8 codes periods, vanishing time of about 22 codes period and time jitter of 2.35 ps is demostrated.