Influence of P-doping in quantum dot semiconductor optical amplifiers at 1.3 µm

P-doped and undoped quantum dot (QD) semiconductor optical amplifiers (SOA) are compared regarding their static and dynamic characteristics. The amplified spontaneous emission and gain curves are evaluated for p-doped and undoped devices exhibiting a gain per length of 10 dB/mm and 7 dB/mm, respectively. P-doped and undoped devices having 22 dB and 23.5 dB chip gain, respectively, were compared in small signal measurements. Cross-gain modulation (XGM) experiments show an enhancement of the small-signal bandwidth from 25 GHz for the p-doped SOAs to 40 GHz for undoped QD SOAs at the same current density. However, p-doped QD SOAs also achieve small-signal bandwidths beyond 40 GHz at larger bias.