Comb-like filter preprocessing to reduce the pattern effect in the clock recovery based on SOA

A novel approach is proposed to reduce the amplitude fluctuation and timing jitter of clock pulses recovered from an injection mode-locked laser based on the semiconductor optical amplifier (SOA) caused by the pattern effect. A comb-like filter is used to preprocess the data pulses that are then injected into the injection mode-locked laser to recovery the clock. Numerical calculation for 40-Gb/s clock recovery demonstrates that this method is very effective for high-speed clock recovery based on the SOA.