Comparative assessment of electrical, photoassisted and all optical in-plane poling of polymer based electrooptic modulators

Abstract

Electrooptic polymer waveguide devices can be easily achieved by simple spin coating of polymer layers, with a transparent polymeric matrix as the passive buffer layer and a side-chain polymer as the active guiding layer. In order to create a non-centrosymmetric EO active material, a classical poling procedure may be adapted, whereby an electrical static field is applied at elevated temperature over the side chain polymer resulting in the polar alignment of the chromophores parallel to the substrate. New poling procedures such as photo-assisted electrical poling (PAP) as well as all optical poling (AOP) are performed by direct illumination of the guiding active layer through the gap between coplanar electrodes. In PAP, the polar order is created by the static electric field acting on the molecules, whereas in all-optical poling the polar order is due to angular non-centrosymmetric hole burning with a multipolar configuration reflecting the polarization symmetry of the interfering laser beams. We propose in the following a comparative assessment of coplanar electrode phase modulators which have been fabricated by these three poling procedures.