We discuss high-speed optical signal processing for telecom applications. We focus on the optical wavelength conversion and self-clocking, respectively. In the optical wavelength conversion, we report 40 Gb/s wavelength conversion that is capable of converting the same wavelength using a single semiconductor optical amplifier. Experimental proofs are presented. In addition, we report a novel self-clocking method based on in-band clock pilot insertion at the transmission data signal. The method provides clock recovery without an ultrafast phase comparator and a phase-locked loop in the receiver. Fast synchronization, low timing jitter and a highly stable recovered clock is demonstrated from 160 Gb/s OTDM data signal after 51-km fiber transmission.