Chapter VI ferroelectric and piezoelectric materials

On the basis of work published in 1963, two trends appear to be taking place: a lessening of interest, particularly in the Russian literature, in barium titanate and other perovskites; and a great increase in interest, particularly in this country, in electro-optic properties. The latter is caused by two recent developments, the use of electro-optic crystals for modulating Laser beams, and the discovery (1961) of frequency doubling of coherent light in piezoelectric crystals. Frequency doubling has now been reported in NH4H2PO4 (ADP), NaClO3, NaBrO3, quartz, tourmaline, CdS, CdSe, InSb, GaAs, and elemental Te, as well as a variety of ferroelectric crystals. In view of the concentrated interest, papers concerning optical harmonics and electro-optic modulation (but not basic measurements) have been collected in a single section.