Suppression of slow gain recovery in ultralong quantum-dash semiconductor optical amplifier emitting at 1.55 μm

Gain dynamics in two quantum-dash semiconductor optical amplifiers of different lengths emitting in the 1.55 μm region are investigated experimentally and compared. It is shown that slow gain recovery due to total carrier relaxation is totally suppressed in the ultralong amplifier. Consequently, the 10%-90% gain recovery time is drastically reduced from about 40 ps (short sample) to 10 ps (long one).