Synthesis and Properties of Polyimide-Based Optical Materials

Abstract

Three types of polyimides (PIs) with different structures and fluorine contents were prepared via a simple two-step method. The PI precursors, poly(amid acid)s (PAAs), were first synthesized from ring-opening polyaddition, then, the PAA films were subjected to thermal imidization. The chemical and the optical properties of the polyimides were investigated and compared. The result showed that all of the polyimides had good thermal stability. The refractive index of the fluorinated polyimide was lower than that of the common polyimide and could be controlled by adjusting the fluorine content in the structure. The second-order nonlinear optical (NLO) coefficient (d33) for the PMDA/ODA polyimide (PMDA = pyromellitic dianhydride and ODA = 4,4’-diamino diphenyl ether) was 10.69 × 10−9 esu at 1064 nm and could be increased to 24.55 × 10−9 esu by doping with a small amount of perylene dianhydride. The optical loss for the PMDA/ODA film and for the 6FDA/ODA film were 0.326 dB/cm and 0.102 dB/cm respectively at 650 nm. Due to many attractive properties mentioned above, polyimide-based materials are expected to have potential applications in the field of organic optical waveguides.