Modeling of the optical piston: Density-wave shape and resonance-fluorescence effects.

Abstract

We present results of a numerical model of the optical piston driven by laser-induced drift (LID). The model is based on a drift-velocity formulation of Lawandy, derived from an asymmetric-random-walk argument, and includes resonance-fluorescence effects. The model is applied primarily to the experimental conditions of H. G. C. Werij and co-workers (Phys. Rev. A 33, 3270 (1986)). It is shown that both the velocity and the shape of the propagating density wave change continuously throughout the traverse of a (finite) diffusion tube under these conditions. In addition, we have numerically verified the contention of G. Nienhuis (Phys. Rev. A 31, 1636 (1985)) that a ''self-preserving'' form of the density wave is indeed possible for the case of a ''finite number of absorbers in an infinite medium,'' both with and without saturation. Finally, we show that resonance fluorescence slows the piston velocity, broadens the density distribution, and decreases its peak height. It is concluded that resonance fluorescence can play a significant role in determining the time evolution and detailed shape of the optical-piston density distribution in sodium.