Enhanced performance of semiconductor optical amplifier at high direct modulation speed with birefringent fiber loop

We employ a birefringent fiber loop (BFL) for enhancing the performance of a semiconductor optical amplifier (SOA) which is directly modulated. By properly exploiting the BFL comb-like spectral response, we show that the SOA can be directly modulated at a data rate which is more than five times faster than that enabled by the SOA electrical bandwidth. The experimental results, which include chirp measurements, demonstrate the significant improvements achieved in the performance of the directly modulated SOA with the help of the BFL.