Self-Induced Transparency and Resonant Self-Focusing in Atomic Iodine Vapor

Self-induced transparency has been observed for the degenerate, $F=3\mathrm{}\to 4$, hyperfine component of the 1.315-μm magnetic dipole transition of atomic iodine, at high optical power levels, up to 50 MW ${\mathrm{cm}}^{-2\mathrm{}}$. For pulse areas approaching $2\pi$, the dynamics of the strong coherent resonant self-focusing which accompanies self-induced transparency have been studied with a streak camera to provide time-dependent analysis of the spatial beam profile.