New Side-Chain Fluorinated Copolymers for Quadratic Non Linear Optics
Khaled Aljoumaa, Elena Ishow, Jianfu Ding, Yinghua Qi, Michael Day and Jacques A. Delaire
Highly fluorinated poly(arylene ether ketone)s and poly(arylene ether sulfone)s containing efficient second order NLO chromophores covalently linked as side-chain groups were synthesized using a polycondensation reaction. The glass transition temperatures of these copolymers were found between 163&Mac176;C and 197&Mac176;C. Second Harmonic Generation (SHG) coefficients (d33) of the poled polymer films (corona poling, voltage 5 kV) reached values of about 14 pm·V-1 at 1907 nm fundamental wavelength. No appreciable decay of the SHG signal was observed below 130°C. These new copolymers allow a compromise to be reached between high transparency at telecommunication wavelengths (associated with the replacement of most of CH bonds by CF bonds), good SHG efficiency and acceptable thermal stability of the dipole orientation.