Oriented films of polyvinylidene fluoride [(CH,CF,),] can be made significantly pyroelectric and optically nonlinear by polingin a field N lo6 voltjcm. Pyroelectric coeflicients as large as 24 nCjcm2C (comparable to single-crystal LiNbO,) and nonlinear optical coefficients comparable to d, of crystal quartz are observed. Simple. inexpensive and fairly rugged pyroelectric detectors for electromagnetic radiation of any wavelength can be made from the poled lilms. Polyvinylidene fluoride (PVF,) crystallizes in a polar phase and it is found that its polarization can be switched. In the sense that it is a switchable pyroelectric PVF, can be regarded as a ferroelectric polymer. piezoelectric,' pyroelectric' and optically nonlinear' by poling them in a strong electric field. The Polyvinylidene Fluoride (PVF,) is a highly crystal- piezoelectric and nonlinear optical coefficients are line polymer having repeat unit CH,CF,. Rolling comparable to those of crystalline quartz, and the and stretching this material produces well-oriented pyroelectric coefficient is comparable to that of (textured) polycrystalline films. It has recently been single-crystal LiNbO,. X-ray and nuclear magnetic found that these films can be made significantly resonance measurements3 indicate that PVF, can