Organic films for guided nonlinear optics

Nonlinear optics has recently developed from a purely basic discipline to a number of research fields focused on potential applications. One fundamental requirement is the implementation of future devices utilizing waveguides. Limiting us to organic materials, this demands the fabrication of homogeneous and hopefully oriented thin films. Here our activity on organic guides with interesting chi(2) or chi(3) nonlinear properties is reported. In particular, four layer guides (FLGs) including 2-docosylamino-5-nitropyridine (DCANP) Langmuir-Blodgett (LB) films have been realized anti used to perform electro-optic tests. A measurement of the Pockel's r22 coefficient gave a value greater than 1/10 of the r33 coefficient of LiNbO3.In the case of chi(3) materials, both LB and spun films have been fabricated. In particular, LB films of poly-3BCMU show a higher degree of conjugation as proved by visible and resonance Raman spectra. This is a straightforward consequence of their ordered structure. In the case of spun films, the reduced conjugation is compensated by relatively easy fabrication and by guide losses as low as 3 dB cm-1 at 1300 nm. Devices based on tapered FLGs were realized to insert polymer films in glass integrated circuits. Moreover nonlinear tests performed by using the propagation at 1064 nm gave a value of chi(3) = 3 10-19 m2 V-2.