Picosecond saturable absorption measurements on thin film single-crystal InAs layers grown by MBE

The linear and nonlinear optical properties of high-quality single-crystal thin (3.3 mu m) MBE films of InAs on GaAs substrates are studied using the lambda =2.94 mu m output of a mode-locked Er 3+ laser. The onset of absorption saturation occurs at pulse energy densities of approximately=100 mu J cm -2 , and a dynamic Moss-Burstein effect model gives a good quantitative explanation of the experimental data. Very rapid adsorption recovery times ( approximately=150 ps) suggest that interfacial recombination is the dominant relaxation mechanism, and indicate the potential for the use of these novel semiconductor heterostructures as fast passive optical shutters for mode-locking and Q-switching applications in the mid-infrared.