Control of The Photoinduced Micro-Patterning of Nonlinear Organic Thin Films: From Molecular to Photonic Engineering

The development of electrooptic polymers now stands at the onset of technological fruition as a result of almost two decades of intense molecular engineering studies and of the more recent maturing of semiconductor compatible integrated optics fabrication processes. Nevertheless, the full potential of organic systems for nonlinear optics(1) and related applications may not have been fully exploited so-far within the paradigmatic orientational scheme of a dipolar molecular diode structure coupled with an externally applied poling electric field at thermal equilibrium. In particular, such a configuration makes it difficult to implement (quasi)-phase matched gratings for (cascaded) quadratic NLO, guarantee polarization independant telecom device behaviour or engineer other propagative (e.g. soliton generation) or QED (e.g. microcavity) configurations. A different approach, whereby all-optical photoinduced processes are called-upon instead of thermally equilibrated ones and traditional 1-D systems are traded for more general 3-D multipolar molecules (e.g. octupolar, dipolar or a combination of these) opens-up new possibilities to adress these issues. It permits indeed to micro-pattern and control with subwavelength accuracy a continuous or pixellised spatial χ(2) tensorial distribution whereby the magnitude and ratios of macroscopic tensorial coefficients are balanced at will by phase and ellipsometric adjustment of the writing beams2.