Nonlinear free-induction decay in semiconductors

Mary‐Ann Mycek, Shimon Weiss, J.‐Y. Bigot +2 more

Jesper Mørk, Antonio Mecozzi

Shimon Weiss, Mary‐Ann Mycek, J.‐Y. Bigot +2 more

We show that the many-body interactions among excitons govern the temporal line shape of the coherent (free induction decay) emission from semiconductor quantum walls. At low exciton densities, they become the dominant contribution to the emission.

Pratima Sen, Kanta Singh, Pratima Sen

Using the time-dependent perturbation treatment of the density matrix, the authors report the occurrence of first-order free induction decay (FID) in narrow direct-gap semiconductors. The analysis deals with the interaction of a near resonant, ultrashort, moderate power laser pulse with the bulk semiconductor sample. Numerical estimates have been made for intrinsic InSb of micrometre size at 77 K irradiated by a frequency doubled 10.6 mu m CO 2 laser with pulse duration in the picosecond domain. The results reveal oscillations, around the background values, in the decay profiles of both the refractive index as well as the absorption coefficient. The transient transmitted intensity has been found to decay in a time comparable to the inhomogeneous Doppler broadening time, which is much shorter that the dephasing time. The analytical behaviour reported here is in very good agreement with the experimental observations of first-order FID in the atomic caesium vapour systems.

Ralph G. DeVoe, Richard G. Brewer

A novel form of laser frequency switching is devised that extends coherent optical transient studies to a 100-picosecond time scale, the measurements being performed in real time. Free-induction decay (FID) on a subnanosecond time scale reveals new features, such as a first-order FID that dephases with the inhomogeneous dephasing time T2* and interferes with the well-known nonlinear FID. A complete analytical expression for optical FID is derived and supports our FID observations for the sodium D1transition.

H. Haug