D.-J. Jang

Carrier recombination dynamics in a (GaInSb/InAs)/AlGaSb superlattice multiple quantum well

We have used the 830 nm, subpicosecond output of a mode‐locked Ti:sapphire laser, together with subpicosecond 3.55 μm pulses from a synchronously pumped optical parametric oscillator, to perform room‐temperature, time‐resolved, differential transmission measurements on a multiple quantum well structure with AlGaSb barriers and GaInSb/InAs superlattice wells. From these measurements, we have determined a Shockley–Read–Hall rate of 2.4×108 s−1 and an Auger coefficient of 7×10−27 cm6/s. In addition, we estimate the carrier capture efficiency into the wells to be ∼52% and have demonstrated that carrier cooling, cross‐well transport, and capture are complete within ∼10 ps after excitation.

Generation of 3-4- mu m femtosecond pulses from a synchronously pumped, critically phase-matched KTiOPO4 optical parametric oscillator.

The operation of a Ti:sapphire-pumped, femtosecond optical parametric oscillator (OPO) based on the nonlinear material KTiOPO4 is described. By empirically optimizing the parametric interaction geometry, we have extended the maximum idler wavelength beyond that reported for similar systems. The OPO typically produces 175-fs idler and signal pulses tunable in the ranges of 2.9–3.96 and 1.05–1.16 μm, respectively.

Hot carrier dynamics in a (GaInSb/InAs)/GaInAlAsSb superlattice multiple quantum well measured with mid-wave infrared, subpicosecond photoluminescence upconversion

We have extended the technique of subpicosecond photoluminescence upconversion to the mid-wave infrared spectral region and have used this system to investigate the energy relaxation of hot, optically injected electron-hole pairs in a narrow-band-gap (2.32 μm) (GaInSb/InAs)/ GaInAlAsSb superlattice multiple quantum well. These and similar structures are currently of interest as the active region for mid-wave infrared diode lasers. The measurements demonstrate that carriers, which are injected with nearly 1 eV of excess energy, are well described by a hot, thermalized distribution in the wells within 2 ps after excitation. For a carrier density of 1017 cm−3, cooling by optical phonon emission is essentially complete 15 ps after injection. By fitting the time dependence of the carrier temperature, we estimate an effective carrier- optical-phonon scattering time of 1.2 ps.