Abstract
The distortion of an intense light pulse by a saturable absorber is analysed on the basis of the dynamic transmission equation. The conclusions are in accord with an earlier numerical analysis for a particular pulse function, but are here proved for arbitrary pulse shape. Bounds are derived for maximum transmittance and energy loss, and the existence of stable periodic solutions is demonstrated. The region in which saturable absorption theory is valid is discussed and compared with that for self-induced transparency. The two phenomena are examples of completely incoherent and completely coherent absorption, respectively.