All-optical poling technique permits purely optical orientation of dye molecules in a polymer film. The experiment includes two phases: the writing (seeding) period and the readout one. In seeding phase two beams, the fundamental (omega) and its second harmonic (SH, 2(omega) ) irradiate the sample and as a result of the coherent interference between them the second order (chi) ⁽²)-susceptibility grating is encoded, with a period satisfying the phase matching condition for SH generation. During the readout step only the fundamental beam is incident onto the material and the second harmonic beam generated by the medium is observed at the back side of the sample. The coherent superposition of two beams at (omega) and 2(omega) frequencies results in a presence of a polar field E(t) inside the material, which can break the centrosymmetry of the medium. The physical origin of the effect lies in the orientational hole-burning in the initially isotropic distribution of dye molecules. It has been demonstrated that efficient all-optical poling requires optimization of relative intensities and relative phase of the seeding beams. An original technique of non-perturbative monitoring of the all-optical poling process without any necessity of taking care of the phase difference between seeding beams is presented. This new technique was applied to several new dye-polymer systems.

Date Published: 13 June 2002
PDF: 8 pages
Proc. SPIE 4642, Organic Photonic Materials and Devices IV, (13 June 2002); doi: 10.1117/12.470453

Published in SPIE Proceedings Vol. 4642:
Organic Photonic Materials and Devices IV
Bernard Kippelen; Donal D. C. Bradley, Editor(s)