Coherent pulse propagation and self-induced transparency on degenerate transitions in atomic iodine

Abstract

Coherent propagation of intense short laser pulses through degenerate absorbing media is investigated with the use of an atomic-iodine laser-absorber self-resonant combination. Four degenerate systems, the ${}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}-{}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$, $F=3\mathrm{}\leftrightarrow F^{\prime }=4\mathrm{}$, $\Delta M_F=0,\pm 1$ and $F=2\mathrm{}\leftrightarrow F^{\prime }=2\mathrm{}$, $\Delta M_F=0,\pm 1$ transitions, are studied under various conditions. Theoretical analysis based on the "pulse-area—pulse-energy" approach shows different pulse propagation behaviors for three typical types of degeneracy. Experimental results give good agreement with theoretical predictions. It is concluded that self-induced transparency exists in any degenerate two-level system, provided that suitable polarization of radiation is used. The usefulness of self-induced-transparency phenomena for measurements of transitional dipole moment and homogeneous relaxation time is also demonstrated.