Coherent control of absorption and propagation in GaAs quantum wells; time and spectral domain studies

Summary form only given. Recently, coherent control of exciton populations has been demonstrated through terahertz, reflection, and four-wave-mixing experiments. However, the most direct probe of exciton population control is the absorption which has been lacking in previous studies. In this report, we probe the time evolution of exciton population directly through a transmission experiment. In particular using up conversion technique with both narrow (spectrally broad) and broad (spectrally narrow) pulses we can obtain both the temporal and the spectral information. The main thrust of our report is that when phase controlled, the second pulse can be either greatly enhanced or completely destroyed by gaining energy from exciton (thus destroying the exciton population) or giving all of its energy to the system (thus greatly increasing the exciton population) respectively.