Characterization of the linear and nonlinear absorption dynamics of aluminum gallium indium arsenide strained-layer multiple-quantum-well semiconductor optical amplifiers.

摘要

This thesis reports on the experimental characterization of novel AlGaInAs strained-layer multiple-quantum-well (SLMQW) semiconductor optical amplifiers (SOAs), for application in ultrafast semiconductor all-optical switching devices. Facilities constructed for performing pump-probe characterization of the temporal dynamics of active semiconductor waveguide devices, which use a picosecond-pulse Ti:sapphire pumped optical parametric oscillator, are demonstrated. Characterization of two important properties of the SLMQW SOAs is then reported: the ultrafast absorption/gain dynamics, and two-photon absorption (TPA) coefficient. The ultrafast dynamics are found to match with expected results from the literature, exhibiting free carrier step responses as well as two-photon absorption and carrier heating dynamics. A free carrier recovery time constant of ∼132 ps is measured, and a dynamic with a time constant of 3.7 ps attributed to carrier heating. The TPA coefficient alpha 2 is found to be 260--415 cm/GW over the 1500--600 nm telecommunications wavelength range. The relatively long carrier decay lifetimes and high TPA of these SOAs indicate they do not represent a significant improvement for all-optical switching, leaving room for additional work to improve SOA designs.