Copolymers incorporating rigid electroactive moieties and flexible segments have been synthesized in an effort to develop non-linear optical materials which can be processed into optical quality films. A variety of coupling linkages have been employed including ether, ester, amide, imine and azo linkages. Among the most attractive materials examined in this survey are heteroaromatic ladder and tetraazaannulene copolymers which yield optical non-linearities (ratioed to optical loss), Z(3)/ct, of 10 -12-10-13 esu cm-1 and have desirable auxiliary properties of high laser damage threshold and fast optical switching (5 ps for three-ring copolymer). Electron donating and withdrawing groups are conveniently incorporated and these have been observed to influence optical non-linearity. The copolymer approach yields linear optical spectra characterized by sharp band edges thus optimizing the window of transparency. Finally, it is noted that this approach yields excellent control of solubility and solution viscosity necessary for spin casting in the fabrication of thin films of uniform thickness.
Посилання на статтю:
Development of materials with enhanced optical non-linearity by control of ultrastructure / L. Yu, D. W. Polis, F. Xiao, L. S. Sapochak, M. R. McLean andL. R. Dalton* // Polymer. – 1992. – Vol 33. – P. 3239-3244.