A phase-conjugate interferometer, based on degenerate four-wave mixing in the retroreflected pump beam configuration, is used to determine the complex third-order hyperpolarizability of organic molecules in solution. The imaginary part of this third-order hyperpolarizability yields a value for the two-photon extinction coefficient of the molecule. This is an absolute value with respect to the reference material and does not depend on the laser intensity used. We show that the observed attenuation in the phase-conjugate signal is not necessarily due to two- photon absorption. In several cases more complex loss mechanisms are responsible for the absorption of the signal.

Date Published: 23 September 1994
PDF: 8 pages
Proc. SPIE 2285, Nonlinear Optical Properties of Organic Materials VII, (23 September 1994); doi: 10.1117/12.187515

Published in SPIE Proceedings Vol. 2285:
Nonlinear Optical Properties of Organic Materials VII
Gustaaf R. Moehlmann, Editor(s)