Saturation in the near-resonance nonlinearities in a triazole-quinone derivative

In this work, we present a study of the third-order nonlinearities of a novel organic material, a derivative of the molecule 2-amino-1,2,3 triazole-quinone. The absorptive and refractive contributions to the nonlinearity were resolved using the z-scan technique with a 88 ps pulse source at 532 nm. The open aperture z-scan results show a nonlinearity arising from a combination of induced and saturable absorption, and the closed aperture the signature of a negative n₂. The irradiance dependence of the closed aperture signal reveals a saturating nonlinearity which even decreases at high irradiances. A three-level model is used to explain the observed irradiance dependence of the nonlinearity. © 2002 Elsevier Science B.V. All rights reserved.