Giant negative and positive Goos–Hänchen shifts via Doppler broadening effect

The magnitude enhancement of the Goos–Hänchen shift (GHS) in reflected light (RL) is investigated. We consider a cavity in which a four-level atomic medium with a double lambda ( )-type configuration is contained. By changing the relative phase of optical fields in the four-level atomic configuration, we obtain normal and anomalous dispersions. Similarly, the manipulation of the positive and negative GHS in the RL is explored via the control of the relative phase. In addition, we investigated the GHS in the RL with and without the Doppler broadening (DB) effect. Interestingly, giant GHS in the RL is revealed for the DB medium. The role of the Doppler width on the magnitude of the GHS in RL is also studied. We find that the magnitude of the negative and positive GHS in the RL increased via increasing the Doppler width.