Vacuum Rabi coupling enhancement and Zeeman splitting in semiconductor quantum microcavity structures in a high magnetic field

Reflectivity spectra of high-quality quantum microcavity structures are investigated in high magnetic fields from 0 to 14 T. Over this field range we observe an increase in the vacuum Rabi splitting by a factor of 1.4, due to the magnetic-field-induced increase of exciton oscillator strength. In addition, exciton Zeeman splitting is seen. We demonstrate that this splitting arises from the independent interaction of each exciton spin component with the corresponding circularly polarized cavity photon mode. We also report anomalous broadening of the higher-energy polariton feature in high magnetic field, raising doubts that the same broadening seen at zero magnetic field is due to coupling of the cavity mode with higher discrete and continuum exciton states.