Nonlinear absorption edge properties of 1.3-μm GaInNAs saturable absorbers -: art. no. 132103

GaInNAs 1.3-mu m quantum-well saturable absorber mirrors are characterized with spectrally resolved nonlinear reflectivity measurements over 70 nm around the broadened band edge. All important parameters such as saturation fluence F-sat, modulation depth Delta R, and nonsaturable loss Delta R-ns are obtained relative to the photoluminescence (PL) peak. F-sat has a minimum of 4 mu J/cm(2) 10 nm above the PL peak and Delta R scales with the linear absorption even in the bandtail. The product Delta R center dot F-sat important to suppress Q-switching instabilities in mode-locked lasers decreases linearly with wavelength and reaches a minimum 20 nm above the PL peak. We observed wavelength-independent nonsaturable losses of only about 10% of the maximum linear absorption. These results increase the understanding of optical and electronic properties of GaInNAs around the band edge. (C) 2005 American Institute of Physics.