Conjugated polymers with degenerate ground state. The route to high performance third-order nonlinear optical response
✍ Scribed by C. Halvorson; T.W. Hagler; D. Moses; Y. Cao; A.J. Heeger
- Publisher
- Elsevier Science
- Year
- 1992
- Tongue
- English
- Weight
- 472 KB
- Volume
- 200
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
Third harmonic generation (THG) measurements on cis-andtrans-polyacetylene demonstrate a symmetry specific mechanism favoring the degenerate ground state: the third-order susceptibility, x('r ( -3w; w, w, w), is an order of magnitude larger in tram-(CH ), than in cis-(CH), over the entire spectral range, even comparing the respective three-photon resonance maxima. Reduced disorder in high-quality oriented tram-( CH), increases x('r (3~) by more than an order of magnitude to values 8 10-8-10-7 esu for fiw within the energy gap. The THG data are consistent with theory which predicts a dominant contribution to $'r (30) from neutral soliton pair intermediate states with As symmetry.