The spectral response of a monolithic semiconductor quantum microcavity with quantum wells as the active medium displays mode splitting when the quantum wells and the optical cavity are in resonance. This effect can be seen as the Rabi vacuum-field splitting of the quantum-well excitons, or more classically as the normal-mode splitting of coupled oscillators, the excitons, and the electromagnetic field of the microcavity. An exciton oscillator strength of 4×${10}^{12}$ ${\mathrm{cm}}^{\mathrm{-}2}$ is deduced for 76-Å quantum wells.

• Received 12 May 1992

DOI:https://doi.org/10.1103/PhysRevLett.69.3314