Characterization of the ultrafast carrier dynamics of an InAs/InGaAsP quantum dot semiconductor optical amplifier operating at 1.55 μm

Self-assembled quantum dot (QD) Semiconductor Optical Amplifiers (SOAs) are believed to have faster carrier recovery times than conventional multiple quantum well, or bulk SOAs. It is therefore of interest to study the carrier dynamics of QD SOAs to assess their potential as ultrafast nonlinear devices for switching and signal processing. In this work we report experimental characterization of the ultrafast carrier dynamics of a novel InAs/InGaAsP self-assembled QD SOA with its peak gain in the important 1.55 μm telecommunications wavelength range. The temporal dynamics are measured with a heterodyne pump-probe technique with 150 fs resolution. The measurements show carrier heating dynamics with lifetimes of 0.5-2.5 ps, and a 13.2 ps gain recovery, making the device a promising candidate for ultrafast switching applications. The results are compared to previous reports on QD amplifiers operating in the 1.3 μm and 1.1 μm spectral regions. This report represents the first study of the temporal dynamics of a QD SOA operating at 1.55 μm.