Clock-Free RZ-BPSK Data Generation Using Self-Starting Optoelectronic Oscillator

A synthesizer-free architecture for 10 Gbit/s return-to-zero binary phase-shift keying (RZ-BPSK) data generation and transmission is demonstrated by using an integrated DFBLD and electro-absorption modulator (EAM) link based self-starting optoelectronic oscillator (OEO). The effects of EAM offset bias and modulation amplitude on the RZ carrier characteristics are numerically simulated. Optimizing the operating parameters of EAM shortens the RZ pulsewidth to 25 ps and enhances the on/off extinction ratio (ER) up to 8.4 dB. Detuning the DPSK demodulator bias to match the frequency comb spacing with the RZ carrier frequency further improves the transmission performance of the clock-free RZ-BPSK data-stream. When comparing with a synthesizer based RZ-BPSK data generator, the receiving sensitivity of the proposed system can achieve -17.7 dBm at BER of 10^-9 with power penalty improving by 2.5 dB.