The nonlinear optical response of sodium vapor when pumped to a two-photon resonance

Author

Mary Anne Kozilsky Moore

Date of Award

8-1988

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Physics

Major Professor

John O. Thomson

Committee Members

Ray Garrett, David J. Pegg, Marvin Payne

Abstract

Although the nonlinear response of sodium vapor to intense laser stimulation has been an active topic over the last three decades, many of the phenomena associated with the two-photon excitation of resonance states have not been fully understood. This study examines primarily three aspects of the nonlinear process associated with the two-photon excitation of either the sodium 3d or 4d states. The first is the suppression of forward hyper-Raman emission due to interference with four-wave mixing emission, and is an extension of previous theoretical and experimental work done in inert gases by the Chemical Physics Section of Oak Ridge National Laboratory.

The second topic is the suppression of backward stimulated hyper-Raman emission due to the a.c. Stark effect. The medium itself generates a near resonance emission that, in turn, generates an electric field of sufficient intensity to cause a shifting of the resonance outside the bandwidth of the incident laser. This has the effect of decreasing the gain for the hyper-Raman process.

The last major section of this study involves the discovery of a new type of process, axially phase-matched four-wave mixing. Normal four-wave mixing emission propagates only in the direction of the laser beam. To phase match in a pure vapor it must propagate conically rather than down the axis of the incident laser beam. This study has shown that four-wave mixing may take advantage of the dispersive properties of the sodium vapor near resonances to index match and propagate coherently down the axis of the laser beam rather than adjusting its cone angle to phase match. Although observations of some of the phenomena reported in this study have been reported in the literature, this is the first time that many of them have been explained satisfactorily in terms of the nonlinear response of sodium atoms.

Recommended Citation

Moore, Mary Anne Kozilsky, "The nonlinear optical response of sodium vapor when pumped to a two-photon resonance. " PhD diss., University of Tennessee, 1988.
https://trace.tennessee.edu/utk_graddiss/11926