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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.

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LiInS2 is an AIBIIIC2VI ternary semiconductor crystallizing with mm2 symmetry. The useful transparency range is 0.5–8 μ, over which we have measured the refractive indices. The optical nonlinear coefficients for second harmonic generation have also been measured. The nonlinear figure of merit is comparable to that of AgGaS2. Three-frequency collinear phase matching is possible in LiInS2 and is analyzed in some detail. LiInS2 is judged to be a potentially more useful optical nonlinear material than the analogous compound LiGaO2.

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A technique has been evolved to generate hydrostatic and uniaxial stress regimes, using a Teflon cell as a container in a conventional piston-cylinder device. Details of the technique and calibration procedure are described. The possibility of using high resistivity as-grown n-GaAs for pressure measurement is indicated. Piezoresistive effects in oriented n-Si plates were used to determine the nature of stress distribution in the pressure medium. The usefulness of the technique to semiconductor studies is pointed out.

It has recently been discovered that the pyroelectric and nonlinear optical properties of polyvinylidene fluoride (PVF2) closely resemble those of a ferroelectric. In this work, we investigate more fully the ``ferroelectric'' behavior of PVF2. Measurements of the pyroelectric properties and polarization reversal are described. Commercially available PVF2 films have been used for radiation detection at 10.6 μm with responsivities of 17 V/W and noise equivalent power (NEP) of 15×10−9 W/Hz1/2 at 100 Hz (0.02-cm2 detector area). Although this NEP is considerably higher than that for other pyroelectric materials, this polymer seems particularly attractive in applications where ultimate detectivity is not required because of the great ease and low cost with which detector films can be constructed in any shape or size.