Abstract

A new laser-assisted poling method was introduced to fabricate organic polymeric materials for second-order nonlinear optical applications. This method provides selective and controllable poling in organic polymers. The large orientation order of nonlinear optical molecular units was evidenced in laser-assisted poled polymers. As a result, polymer thin films with a large second-harmonic nonlinearity can be fabricated. From the measurements of second-harmonic generation in thin-film geometry, second-harmonic coefficients were found to be d₃₃ = 168 ± 18 pm/V and d₃₃/d₁₃ = 7 ± 2 at 1320 nm. Experimental results indicate the improvement of molecular alignment by laser-assisted poling methods in comparison with the nonlinear properties of the same material poled with tradition poling scheme. We have also incorporated nonlinear optical function units into photoinduced, cross-linking linear polymer chains. Long-term stability of the molecular orientation was achieved by fixing the aligned nonlinear units with the cross-linking technique. Because of the selective poling ability, laser-assisted poling techniques can be used to fabricate nonlinear channel waveguides, grating input couplers, and waveguides for quasi-phase-matching second-harmonic generation.

© 1990 Optical Society of America