Linewidth reduction and frequency stabilization of semiconductor lasers using dispersive losses in an atomic vapor

The effects of a dispersive loss on the linewidth and chirp of a semiconductor laser are discussed. A van der Pol analysis is used to obtain expressions for linewidth reduction and chirp reduction in an arbitrary optical feedback configuration. Specifically, the use of an atomic cesium vapor as a dispersive loss mechanism is considered. The dominant factor in reducing the linewidth and chirp is shown to be the frequency-dependent phase change from the atomic vapor. However, it is shown that under certain operating conditions the frequency-dependent amplitude changes from the atomic vapor also contribute to the reduction. The results are shown to be in agreement with a detailed rate equation calculation