Vapor deposited organic thin films with large third order nonlinearities for integrated nonlinear optics

We used vapor deposition in high vacuum to fabricate homogenous organic thin films for third-order nonlinear optics. We used small molecules that have a high third order polarizability, are robust, and can be sublimated without decomposition. The most important example is 1,1,2-tricyano-2-[(4-dimethylaminophenyl)ethynyl]ethene (TDMEE), which has a \textit{specific} third order polarizability one order of magnitude larger than other highly nonlinear molecules. It is a member of a family of donor-substituted cyanoethynylethene molecules that has recently been found to have polarizabilities that approach Kuzyk's fundamental limit.\footnote{J. C. May et al, Opt. Lett. 30, 3057 (2005)} The organic thin films have a high, flat transmission above 1000 nm, a high two-photon absorption near 1200 nm, and an essentially real third order polarizability at 1.5 $\mu$m that is three orders of magnitude larger than fused silica.