Thermally Stable Poled Polymers: Highly Efficient Heteroaromatic Chromophores in High Temperature Polymers

Abstract

There has been considerable interest in developing processible, thermally stable second order nonlinear optical thin films using the poled polymer method. Thermoplastic guest-host polymers or copolymers have demonstrated the feasibility of getting higher electro-optic coefficients than that of lithium niobate. However, these polymers generally have low glass transition temperatures so that the poled polymers suffer from the thermal re-orientation of chromophores within the polymer host. This strongly limited the use of these polymers for practical applications. Polyimides have been reported in recent years as the promising host for the nonlinear optical chromophores due to their high glass transition temperatures and compatibility with semiconductor processing technologies. However, to use polyimides as the host, the guest chromophores must be able to sustain the stringent chemical environment during the high temperature processing of polyimides. The conventionally used nonlinear optical chromophores generally decomposed during the process. Furthermore, since the loading density of chromophores in a guest-host form is lower than that of a side-chain copolymer system, the resultant bulk nonlinear optical properties are generally smaller. Thus, for guest-host polyimides, chromophores with higher βμ values are reguired to maintain or exceed the demonstrated bulk nonlinear optical properties in copolymer systems.