Reversible, nonlinear (saturable) absorption is useful when deep penetration of light into dye layers, beyond the exponential depth in Beer’s law, is required. Examples are in the photomechanics of nematic elastomers, or in the two-color simultaneous absorption exploited to lithographically write structures in the deeply subwavelength region. We explicitly calculate the intensity distribution and the dynamics of its development from the three nonlinear coupled partial differential absorption equations for strong two-color interactions with dye layers. We show how the nonlinearity produces sharp transverse profiles of one color at the expense of the other.

• Received 6 May 2009

DOI:https://doi.org/10.1103/PhysRevA.80.033833