Optical Fermi-edge singularities in a one-dimensional electron system with tunable effective mass

We have investigated the dependence on the magnetic field of the optical absorption and emission of a one-dimensional (1D) electron gas in GaAs quantum wires with one occupied subband. Spectra show a strong Fermi-edge singularity that narrows as the Fermi energy in the wires is continuously reduced by the enhancement of the effective mass in a perpendicular magnetic field. At high fields, when the cyclotron energy is larger than the 1D subband spacing, the lowest optical transition splits into a doublet due to the spatial modulation of the Landau levels by the wire potential.