Slow carrier-phonon interaction in InGaAs-InGaAsP multiquantum well investigated by time-development of carrier temperature and gain

Carrier temperature and gain transients were measured, on a picosecond time scale, for a 1.5 μm-band multiquantum-well (MQW) semiconductor laser (LD) amplifier. The transients were analyzed using extended rate equations, which deal with carrier-longitudinal optical (LO) phonon interaction, and carrier excitation due to Auger recombination. Carrier-LO phonon interaction was found to be extremely slow at high carrier density. For the electron intrasubband scattering, the time constant was estimated to be 7 ps, which was one order of magnitude larger than the calculated value even if the Coulomb screening was taken into account. Auger-excited carrier was found to mainly overflow and to have a minor effect on the carrier temperature. On the basis of these conclusions, light output saturation in the MQW-LD is discussed