Coherent Control Of Semiconductor Optoelectronic Properties

Historically, phase has received little attention as a parameter which can be used to control the properties of matter. Recently, however, coherence control of physical and chemical properties of simple systems using two or more laser beams has been demonstrated [1-3]. The possibility of influencing the phase of matter by controlling the phase of light arises from the fact that two or more phased perturbations which can connect the same initial and final states in a system can lead to interference effects between the different quantum mechanical pathways and therefore influence the final state of matter. In this talk we report two manifestations of this effect in bulk semiconductors, namely the generation and control of carrier density and electrical currents [3] in a bulk, unbiased semiconductor when both initial and final states are in the continuum (valence and conduction bands). The observations of such effects is not only intellectually appealing but may point the way to novel device applications. In initial experiments, control has been achieved in GaAs at room temperature using picosecond and 100 fs optical pulses at 1550 and 775 nm. The talk will focus on the description of these phenomena in terms of quantum mechanics as well as nonlinear optics. The influence of beam parameters and sample characteristics will be discussed.