Coherent Exciton Dynamics in InP Nanowires

Three-Beam Heterodyne Four-Wave Mixing (HFWM) measurements provide insights into coherent and ultrafast processes present within indium phosphide nanowires grown with selective area epitaxy (SAE). Measurements with and without Al₂O₃ protective coatings illuminate inhomogeneous and homogeneous broadening effects along with excited state dynamics. For coated samples, inhomogeneous broadening due to surface strain from the protective coating contributes to shorter coherence times, while the coating allows for longer system lifetimes. In uncoated samples homogeneous broadening dominates and splitting effects are observed potentially due to the higher prevalence of molecular contaminants at the surface of samples. Systems are modeled using a two-level solution to the optical Bloch equations which include terms accounting for Excitation Induced Dephasing (EID) and Phase Space Filling (PSF). This model allows for the determination of splitting energy and distinguishes between polarization and entanglement-based beatings.