PYROELECTRICITY AND OPTICAL SECOND HARMONIC GENERATION IN POLYVINYLIDENE FLUORIDE FILMS

Oriented films of polyvinylidene fluoride [(CH2CF2)n], a polar polymer possessing symmetry mm2, can be made significantly pyroelectric and optically nonlinear by poling in an electric field. A pyroelectric coefficient (dP/dT = 2.4 ± 0.7 nC/cm2°C) comparable to that of single-crystal LiNbO3 is observed. The nonlinear optical coefficients d33, d32, and d31 of polyvinylidene fluoride (PVF2) are measured relative to d11 of crystalline quartz [d33 (PVF2)≃2d31 (PVF2) ≃d11(SiO2); d32(PVF2)≃0]. The poled films have specific advantages for pyroelectric detection of electromagnetic radiation and for optical parametric devices.