Alkyl sulfone-containing optical polyimide for an efficient wavelength conversion

Several organic chromophore derivatives have been investigated to get a high optical nonlinearity and low optical loss for nonlinear optical devices. The pi-conjugation length and polar substituents of the chromophore are limited due to an optical propagation loss caused by the chromophore structure. A nitro group is inappropriate for the stilbene fused chromophore because of its strong polarizing power but sulfones exert a reasonable polarizability for the generation of a low optical propagation loss. Three side chain polyimides (PI-Dass, PI-Rdas and PI-Drdas) with sulfone chromophores exhibited optical propagation loss of ca. 3.2 dB/cm at 0.78 μm. According to the binding structure of the chromophore on the polymer, sulfone binding resulted in better optical nonlinearity than amino binding. A hyper branched structure contributes to the increment of the optical nonlinearity of the sulfone chromophore. Absorption spectrum analysis is performed with both solution and solid film of the optical polymer in order to examine the chromophore structure relating to the optical propagation loss.