Measurement and calculation of the critical pulsewidth for gain saturationin semiconductor optical amplifiers

The nonlinear gain response of InGaAsP bulk optical amplifiers under ultraf ast optical excitation at 1.53 mu m is investigated. In particular, the dep endence of the gain saturation energy on the pulse duration is measured in the range of pulse durations from 150 fs to 11 ps, for different bias curre nts and lengths of the amplifier. By comparison with a theoretical model, a critical pulsewidth is inferred below which nonlinear carrier dynamics Lik e carrier heating and spectral hole burning dominate the gain saturation. ( C) 1999 Elsevier Science B.V. All rights reserved.