On-chip microfabricated capillaries for hyper Rayleigh scattering of nonlinear-optical organic molecules

ABSTRACT The microfabrication of an on-chip capillary system using photolithography as well as etching and aligned bonding techniques is presented. Also the optical properties of the capillary waveguide are described. These are very satisfactory forhyper Rayleigh scattering (HRS) as measurements confirm.Keywords: fused silica, chemically wet etching technique, aligned bonding technique, micro flow module, leaky opticalwaveguide, capillary waveguide, hyper Rayleigh scattering, two photon absorption 1. INTRODUCTION In recent years organic molecules with nonlinear optical properties have gained significance, for instance in photomcs andoptoelectroriics1 in connection with optical data storage and all-optical switching. On the way to a technical application thecharacterization of these organic molecules is central.The nonlinear coefficients in organic media have their primary origin in the nature of the individual molecules2. A keymolecule nonlinear parameter is the first hyperpolarizability /3lmn. It is a third-rank tensor, but in consideration of specialmolecule symmetries the tensor can usually be reduced to just a few non-zero components. A common way to measure thefirst hyperpolarizability is hyper Rayleigh scattering3 in solutions of these nonlinear-optical organic molecules. This meanslight scattering at an angular frequency 2w