Superimposed microwave modulation at two times the bit frequency: Characteristics and performance in gbps systems

We investigate the superimposition of a strong phase-locked microwave signal applied at twice the DATA frequency for applications in Gbps multimode fiber (MMF) systems. By phase-locking the auxiliaiy microwave signal (AMS), an excessive jitter on the receiver output is avoided, and any intermodulation penalty is eliminated. Because the AMS frequency is only twice the bit frequency, it is feasible to place the AMS driver chip remotely from the laser package. The investigation is mostly based on simulations at 1.06 Gbps. System experiments were conducted to verifi the reduction in modal noise and elimination of intermodulation distortion.