Electrooptical Effects of “Single-Crystalline” Films of Ferroelectric Copolymers of Vinylidene Fluoride and Trifluoroethylene

“Single crystalline” (SC) films of vinylidene fluoride (VDF) and trifluoroethylene (TrFE) copolymers (P(VDF/TrFE)) which are highly double-oriented films, do not form an intricate highly ordered structure, for example, a lamellar structure, but a simple one. After a SC film is poled under a dc electric field, one-to-one correspondence can be observed between the macro-(drawn and poling axes) and optical axes in a SC film of P(VDF/TrFE). Therefore, linear electrooptical effects of SC films of P(VDF/TrFE) can be measured at room temperature and constant stress. We then found a large electrooptical coefficient in SC films of P(VDF/TrFE).