title: Femtosecond gain and index dynamics in an InAs/InGaAsP quantum dot amplifier operating at 1.55 microm.
abstract: We report on the characterization of the ultrafast gain and refractive index dynamics of an InAs/InGaAsP self-assembled quantum dot semiconductor optical amplifier (SOA) operating at 1.55 mum through heterodyne pump-probe measurements with 150 fs resolution. The measurements show a 15 ps gain recovery time at a wavelength of 1560 nm, promising for ultrafast switching at >40 GHz in the important telecommunications wavelength bands. Ultrafast dynamics with 0.2-1.5 ps lifetimes were also found consistent with carrier heating and spectral hole burning. Comparing with previous reports on quantum dot SOAs at 1.1-1.3 mum wavelengths, we conclude that the carrier heating is caused by a combination of free-carrier absorption and stimulated transition processes.
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Zilkie
authors.forename: Joachim
authors.initials: J
authors.lastname: Meier
authors.forename: Peter W E
authors.initials: PW
authors.lastname: Smith
authors.forename: Mo
authors.initials: M
authors.lastname: Mojahedi
authors.forename: J Stewart
authors.initials: JS
authors.lastname: Aitchison
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Poole
authors.forename: Claudine Nì
authors.initials: CN
authors.lastname: Allen
authors.forename: Pedro
authors.initials: P
authors.lastname: Barrios
authors.forename: Daniel
authors.initials: D
authors.lastname: Poitras