Abstract: Film comprising at least one unimolecular layer. A film for use in nonlinear optics comprises at least one Langmuir-Blodgett layer, the layer containing or comprising a dye of the formula ##STR1## in which R.sup.1 denotes a long-chain alkoxy, acyloxy, alkylamino or acylamino group. In particular when the film contains alternating layers of unsaturated amphiphilic compounds, it produces a stable multilayer having good monlinear optical properties and is suitable, for example, for electrooptical switches, diode laser frequency amplifiers or optical parametric amplifiers.Besides the dye indicated, the unimolecular layer can additionally contain at least one second amphiphilic compound. In this case, the unimolecular layer comprises amphiphilic compounds.

Abstract: The film consists of one or more Langmuir-Blodgett layers, the layer containing an organic polymer having long-chain fluoroalkyl side groups or consisting of this compound. The film is distinguished by a multilayer structure having few defects and is, for example, suitable for optical purposes and for surface treatment. The order of the molecules in the multilayer can be improved by annealing and by heating the film through the phase transition and cooling again.