Optical free induction decay

The time dependent perturbation technique has been employed to study the ph enomena of optical free induction decay (FID) in semiconductors where the r adiation field is quantised. The theory developed for a two-level system is subsequently extended to a semiconductor by treating the semiconductor as inhomogeneously broadened N-two-level systems. The numerical analysis has b een made for samples of InSb and GaAs duly irradiated by near resonant lase rs. It has been found that the incorporation of vacuum field fluctuations g ive rise to an oscillatory FID signal.