Abstract

Molecular compounds with double-conjugated bonds (dyes) possess abnormally high optical nonlinearitites. The typical values of χ⁽³⁾ for these molecules are comparable with resonant nonlinear atomic susceptibilities of metals, which is due to the collectivization of unpaired π-electrons in a chain of doubleconjugated molecular bonds. In a number of papers (see e.g. ^[1-3]) dye vapors are reported to have been used as a novel nonlinear medium for the parametric UV and VUV generation. In order to investigate the nonlinear optical properties of such compounds and to obtain maximum conversion efficiencies it is necessary to have knowledge of the effect of the limiting processes. The easiest way to observe the limiting processes in the third-harmonic generation of a sufficiently high-power laser is examining the dependence of the output power P_3υ on the incident power P_υ. It is obvious that in third-order processes this is a cubic dependence. Any deviation from this behavior may be considered as an indication of the influence of the accompanying processes.

© 1992 IQEC