Laser-Induced Atomic Structure

Michael E. St. J. Dutton, Bryan J. Dalton

Laser induced continuum structures (LICS) can be produced by a strong laser embedding an excited atomic bound state into a flat atomic continuum, leading to a tunable resonance of adjustable width that can be probed by a second laser. If this second laser is of similar intensity to the embedding laser then the distinction between the two becomes artificial and saturation effects become important. In this paper the effect on LICS of transitions caused by both lasers between the original atomic continuum and a second atomic continuum are studied in the Markoff approximation by means of Laplace transform methods and allowing for the ionization of each atomic state by both laser fields. Formal results correct to all orders are also given in terms of a T-matrix approach. Numerical calculations are presented showing the effects on the LICS resonant structures of continuum-continuum coupling processes. Significant changes to the Fano profiles (second laser weak) and to coherence holes (second laser strong) occur. Analytical results are also given.

P. L. Knight, M.A. Lauder, Bryan J. Dalton

Niels J. Kylstra, O. Latinne, Martin Dörr +5 more

Atomic states may be embedded in the continuum by dressing the atom by an intense laser field. This is often referred to as a laser induced continuum structure (LICS) [1]. This continuum, in general, also has a natural structure due to the doubly excited states, or autoionizing states, of the atom. We have considered the situation in which a complex atom or ion is subjected to an intense laser field such that the LICS states and autoionizing states occur simultaneously. We have have found that, by tuning the frequency and intensity of the field, the states can become degenerate, i.e. have the same position and width.

Alain Aspect

Alain Aspect

Michael E. St. J. Dutton, Bryan J. Dalton

Laser-induced continuum structures (LICS) can be produced by a strong laser embedding a low-lying atomic state into a flat atomic continuum, which leads to a tunable asymmetric Fano resonance of adjustable width that can be probed by a second weak laser. In this paper the effects on LICS of transitions caused by the embedding laser between the original atomic continuum and a second atomic continuum are studied in the Markoff approximation by means of Laplace transform methods. Formal results correct to all orders are presented in terms of a T-matrix approach. Numerical calculations are presented which include continuum-continuum coupling correct to the lowest power of the embedding laser intensity. The time evolution of the pure LICS Fano profile is also shown.