Regenerative Amplification by Using Self-Phase Modulation in a Quantum-Dot SOA

We experimentally demonstrate regenerative amplification of 10-, 20-, and 40-Gb/s return-to-zero signals exploiting a simple scheme based on self-phase modulation (SPM) in a columnar quantum-dot (CQD) semiconductor optical amplifier (SOA) and the use of a red-shifted off-set filter. We study the signal Q(2)-factor improvement as a function of the input power to the amplifier. We also report results using a quantum-well (QW) SOA for comparison. We find that the SPM-based regenerative amplification is only possible in the quantum-dot amplifier.