Macromolecular Rapid Communications, Vol.22, No.3, 185-188, 2001
Large photoinduced refractive index change in a polyimide film by charge-transfer complex formation with a polymer-bound phenylazide fragment
A large photo-induced refractive index change as large as 0.014 at 632.8 nm in thermostable transparent polymer films has been realized for the first time by using photoirradiation of polyimide precursor films containing a phenylazide and successive imidization. The phenylazide fragment forms a charge-transfer complex with imide moiety. The films maintained high transmittance in a wide visible region in contrast to usual polyimide films. This value of refractive index change is sufficient to make thermostable channel waveguides and other optical devices.