Femtosecond Four-Wave Mixing Experiments on GaAs Quantum Wells Using Two Independently Tunable Lasers

Femtosecond two beam and three beam ( ${\omega }_1,{\omega }_1;{\omega }_2$) four-wave mixing (FWM) experiments on GaAs quantum wells have been performed using two partially synchronized, independently tunable lasers with external jitter compensation. Heavy and light hole beatings are observed with these two mutually incoherent lasers. FWM signals are observed when ${\omega }_2$ is completely below the exciton energies, with no spectral overlap with the absorption profile. These off-resonant signals are stronger than the interband continuum signals for equivalent detunings.