Above‐ and below‐band femtosecond nonlinearities in active AlGaAs waveguides

Femtosecond optical pulses were used to study the gain and refractive index dynamics in a bulk AlGaAs diode laser. Experiments were performed at wavelengths above and below the band gap of the diode‐laser active region. The above‐band gain dynamics exhibit an ultrafast transient that has not been seen before in AlGaAs devices. We attribute this dynamic to spectral‐hole burning and a delay in carrier heating. The below‐band refractive index measurements demonstrate that carrier heating by free‐carrier absorption is important and that there is a delay in the onset of this heating of approximately 120 fs.

[1]  J. Mork,et al.  Nonlinear gain suppression in semiconductor lasers due to carrier heating , 1991, IEEE Photonics Technology Letters.

[2]  Erich P. Ippen,et al.  Subpicosecond gain dynamics in GaAlAs laser diodes , 1987 .

[3]  James G. Fujimoto,et al.  Femtosecond measurements of the nonresonant nonlinear index in AlGaAs , 1990 .

[4]  Akihisa Tomita,et al.  Observation of highly nondegenerate four‐wave mixing (≳1 THz) in an InGaAsP multiple quantum well laser , 1991 .

[5]  Wilson Sibbett,et al.  Observations of ultrafast nonlinear refraction in an InGaAsP optical amplifier , 1991 .

[6]  Peter J. Delfyett,et al.  Hot‐carrier thermalization induced self‐phase modulation in semiconductor traveling wave amplifiers , 1991 .

[7]  L. F. Tiemeijer,et al.  Effects of nonlinear gain on four‐wave mixing and asymmetric gain saturation in a semiconductor laser amplifier , 1991 .

[8]  W. Elsasser,et al.  Four-wave mixing in GaAs/AlGaAs semiconductor lasers , 1989 .

[9]  Erich P. Ippen,et al.  Ultrafast refractive index dynamics in AlGaAs diode laser amplifiers , 1991 .

[10]  M. Kakui,et al.  Observation of highly nondegenerate four-wave mixing in 1.5 mu m traveling-wave semiconductor optical amplifiers and estimation of nonlinear gain coefficient , 1992 .

[11]  Gadi Eisenstein,et al.  Femtosecond gain dynamics in InGaAsP optical amplifiers , 1990 .

[12]  Origin of nonlinear gain saturation in index‐guided InGaAsP laser diodes , 1992 .

[13]  James G. Fujimoto,et al.  Femtosecond dynamics of the nonlinear index near the band edge in AlGaAs waveguides , 1990 .

[14]  U. Koren,et al.  Carrier heating and spectral hole burning in strained-layer quantum-well laser amplifiers at 1.5 μm , 1992 .