Third-order optical nonlinearities of α,ω-dithienylpolyenes and oligo(thienylvinylene)

α,ω-Dithienylpolyenes and oligo(thienylvinylene) are interesting third-order nonlinear optical materials for a variety of device applications. To better understand the third-order nonlinear response of these materials, the third-order susceptibilities ( χ (3)) and nonlinear absorption behaviors of t...

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Bibliographic Details
Published in:	Optics communications Vol. 215; no. 1; pp. 185 - 190
Main Authors:	Sun, Wenfang, Bader, Mamoun M, Carvalho, Taiala
Format:	Journal Article
Language:	English
Published:	Amsterdam Elsevier B.V 01-01-2003 Elsevier Science
Subjects:	Beam trapping, self-focusing and defocusing; self-phase modulation Degenerate four wave mixing Exact sciences and technology Fundamental areas of phenomenology (including applications) Nonlinear absorption Nonlinear optics Oligo(thienylvinylene) Optical materials Optical susceptibility, hyperpolarizability Optics Phase conjugation, optical mixing; photorefractive and kerr effects Physics Polymers and organics Reverse saturable absorption Saturable absorption Third-order optical nonlinearity Third-order susceptibility α,ω-Dithienylpolyenes Reverse saturable absorption Third-order optical nonlinearity Saturable absorption Degenerate four wave mixing α,ω-Dithienylpolyenes 42.65.Pc 42.70.Jk 42.65.An Oligo(thienylvinylene) 42.65.Hw Nonlinear absorption Third-order susceptibility Optical limiting Four-wave mixing Experimental study Absorption coefficients Nonlinear optical susceptibility Oligomers Thiophene derivatives Sulfur heterocycle Polyenic compound Optical saturable absorption Optical properties Nonlinear optics Organic compounds
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Summary:	α,ω-Dithienylpolyenes and oligo(thienylvinylene) are interesting third-order nonlinear optical materials for a variety of device applications. To better understand the third-order nonlinear response of these materials, the third-order susceptibilities ( χ (3)) and nonlinear absorption behaviors of two α,ω-dithienylpolyenes with different conjugation length and two oligo(thienylvinylene) with different substituents on the thiophene rings have been studied using degenerate four wave mixing (DFWM) and nonlinear transmission techniques at 532 nm. The χ (3) values of 1×10 −3 mol/l solutions are all of the order of 10 −13 esu. The χ (3) values increase with the increase of the linear absorption coefficient. In addition, these compounds exhibit reverse saturable absorption for nanosecond laser pulses. The strength of reverse saturable absorption varies when the conjugation length and substituents change. Moreover, the nonlinear absorption characteristics of these compounds in the picosecond regime differ from those in the nanosecond regime. The different nonlinear absorption behavior is due to the relative contributions from excited singlet–singlet and triplet–triplet absorption. The strong reverse saturable absorption characteristics of two of the compounds suggest that they could be potential candidates for optical limiting applications in the nanosecond regime.
ISSN:	0030-4018 1873-0310
DOI:	10.1016/S0030-4018(02)02187-9