Optical power limiting based on two-photon absorption: a promising approach with conjugated oligomers

摘要

The nanosecond nonlinear absorption of organic molecules is a three-photon process, i.e. a two-photon initiating step followed by a transient absorption during the pulse duration. Order of magnitude calculations show that it is realistic to consider two-photon absorbing molecules for optical limiting applications at visible wavelengths. In this work we have investigated two molecular engineering approaches to optimize molecules: internal charge transfer molecules and conjugated oligomers. The oligomer approach is the most promising due the enhancement of nonlinearities that results from cooperative effects between monomers.