Cooling of a semiconductor by luminescence up-conversion

We report the observation of phonon-mediated up-conversion of luminescence in a GaAs quantum well. This opens the possibility of light-induced lattice cooling in a semiconductor. Under appropriate conditions, pumping the sample with light at the energy of the heavy-hole exciton, we observe light-hole exciton emission, which lies similar to 10 meV above the excitation energy. The use of an external magnetic field together with the resolution of excited excitonic states provides an internal thermometer to monitor the sample temperature. Temperature drops as large as 10% of the initial temperature are observed for pump densities of 4 W cm(-2). (C) 1999 American Institute of Physics. [S0003-6951(99)00435-0].