A Fabry-Perot (F-P) etalon and a semiconductor optical amplifier (SOA) were combined to preprocess the data signals before clock recovery. With this technology in the 10-Gb/s clock recovery utilizing injection mode-locked laser (IMLL) based on SOA, the amplitude fluctuation and timing jitters caused by the pattern effect in recovered clock pulses were greatly reduced, experimentally. It also demonstrated that clock could be recovered from the very degraded signals.