Picosecond Gain Recovery Dynamics in Semiconductor Optical Amplifiers and Three-Wavelength Devices

Based on density matrix equations, a broad-band time-domain large-signal model for semiconductor optical amplifiers (SOAs) is established. Accounting for spectral hole burning, carrier heating and carrier density modulation (CDM), we analysis the gain dynamics in a SOA stimulated by a 1ps pump pulse. On picosecond timescale, the ultrafast component of gain recovery dynamics is wavelength dependency. Furthermore, in three-wavelength devices, the long-lived recovery tail induced by CDM can be reduced by proper continuous-wave assistant light in gain region close to gain transparency point. And then the full gain recovery time up to 1.04ps is obtained.