The optical-limiting behavior of a series of trans-α, ω-diphenyl polyene compounds was observed in solutions of chloroform. The influence of planarity, the substitution of donor and acceptor groups, and the extent of π-electron delocalization on the nonlinear thresholds of the diphenyl polyenes in an optical-limiting geometry were examined. A saturation effect of optical-limiting nonlinear thresholds, consistent with the theoretical work, was observed at 10–11 π-electron bonds. The temporal profiles of the transmitted laser pulses and the power dependence of the nonlinear thresholds as a function of spot size and wavelength were examined. These examinations led to the conclusion that the predominant nonlinear mechanism was quasi-steady-state self-focusing. Nonlinear thresholds an order of magnitude lower, and thus effective n2 and X3 values an order of magnitude higher, than the well-known self-focusing medium CS2 were observed. Our studies demonstrate that this series of polyenes consists of efficient broadband nonresonant optical-limiting materials.
© 1991 Optical Society of America
T. J. Bunning, L. V. Natarajan, M. G. Schmitt, B. L. Epling, and R. L. Crane, "Optical limiting in solutions of diphenyl polyenes," Appl. Opt. 30, 4341-4349 (1991)