The noise figure degradation due to saturation by amplified spontaneou
semission of high-gain 1310-nm polarization insensitive multiple-quant
um-well optical amplifiers has been investigated systematically by stu
dying amplifiers of different lengths. It is found that the intrinsic
noise figure of 4 dB of a device with 20-dB single-pass gain is degrad
ed to about 5 dB for a device having 36-dB single-pass gain. This degr
adation in noise figure is very modest, compared to results reported e
arlier for semiconductor optical amplifiers with bulk-gain media, illu
strating the benefits of using a quantum-well gain medium in semicondu
ctor optical amplifiers.