High-speed 1.55 mu m Fe-doped multiple-quantum-well saturable absorber on InP

Excitonic saturable absorption on iron-doped InGaAs/InP multiple-quantum-we ll structures is studied by Fourier transform infrared spectroscopy and pum p-probe measurement in the 1.55 mum wavelength range. The recovery time of the excitonic absorption bleaching is improved by iron doping and is found to vary from 7 ns on the undoped sample to 7 ps on the highest doped sample . The samples exhibit high optical switching with a differential optical tr ansmission coefficient of more than 20% and a saturation fluence smaller th an 47 muJ/cm(2). Furthermore, we notice no degradation of the contrast rati o due to iron doping. (C) 2001 American Institute of Physics.