Second-harmonic generation from organic molecules incorporated in sol-gel matrices

Abstract

Orientation of optically nonlinear organic molecules inside sol-gel matrices upon application of an external D.C. electrical field is demonstrated for the first time. The quadratic nonlinear response of silicon oxide or transition metal oxide based gels containing organic molecules has been determined from Electric Field Induced Second Harmonic (EFISH) measurements. Large concentrations of Optically Nonlinear Organic Molecules (ONOM) have been either incorporated inside the macromolecular network or chemically bonded to the oxide backbone of the gels. These results demonstrate the feasibility of permanently poled doped sol-gel matrices. Moreover, EFISH measurements performed on organic molecules appear to be a useful tool for monitoring the changes occurring during sol-gel transformations.

Stilbazolium-MPS 3 Nanocomposites with Large Second-Order Optical Nonlinearity and Permanent Magnetization

“…Intercalation provides an alternative to sol-gel methods (28), at least in certain circumstances, for the synthesis of hybrid organic-inorganic nanocomposites, providing the advantage of a better crystallinity that can be im~ortant when coouerative interactions are reiuired. We did not' record any sigruficant decay of the NLO signal over a period of several months, which is a crucial point in the search for suitable SHG materials.…”

Optical Properties of Hybrid Organic‐Inorganic Materials and their Applications

“…[46,271] In the sol-gel process, two approaches are commonly proposed, either simple dispersion with low energy coupling (Class I) or covalent bonding with strong coupling (Class II), the latest being often mentioned as the most stable one. Since the very precursor works in the early 90's when was demonstrated the efficient doping and orientation of dyes in inorganic matrices, [272] large number of reports explored the capacity of sol-gel matrices to stabilize the orientation of chromophores. Large second order optical nonlinearities were observed using covalent grafting of the dyes to the silica backbone.…”

Visualization of Surface Gelation Processes in a Doped Sol-Gel Glass

“…Studies of the dopant dynamics of a tetramethoxysilane (TMOS)/dimethylaminopyridine (DMAP) sol ± gel have shown that the sol phase is characterized by an increase in length of polymers with time which results in an increasing viscosity of the medium. [15] Macroscopic gelation occurs when the longer polymer species are consumed to form the long-distance network. This process results in a temporary decrease in hindrance (local viscosity) around dopant molecules and b-carotene experiences a sudden return to a solventlike environment.…”