20 GHz optical pulse generation based on a 10 GHz optoelectronic oscillator

An optical pulse generation with repetition-rate of 20 GHz based on a 10 GHz optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. The combination of an optical comb generator (OFCG) and an OEO can generate an optical pulse train with the features of high repetition-rate, narrow pulse-width and low timing-jitter, simultaneously. By tuning the DC bias voltage applied on the OFCG, the modulated output light of the OFCG appears as a 20 GHz single optical pulse train which has a repetition-rate twice of the 10 GHz modulation frequency of the OFCG. It improves the repetition-rate of the optical pulse. A microwave frequency divider with dividing ratio of 2 is used to obtain an electrical signal with frequency equals to the 10 GHz modulation frequency. The output of the microwave frequency divider is fed back to drive the OFCG to form a closed OEO loop. Compared with the former ways, it eliminates the optical bandpass filter (OBPF), which improves the power efficiency of the OEO loop.