Abstract
Optical absorption, refractive index, dielectric constant, nonlinear optical coefficients, and linear electro-optic coefficients are reported for single-domain crystals of Na between room temperature and the Curie temperature. Orthorhombic () barium sodium niobate, a filled tungsten-bronze structure, is stable to intense laser radiation, and its phasematchable nonlinear coefficients are 3 times those of LiNb and LiI. For the 1.064-μm laser fundamental, the observed phase-match temperatures and the angular half-widths of the phase-matched second-harmonic intensity due to the coefficients and are found to be in good agreement with the values calculated from refractive-index data. The dielectric constant and electro-optic half-wave voltage data indicate that Na is a useful electro-optic modulator material. The temperature variation of the spontaneous polarization is deduced from the birefringence, electro-optic, nonlinear optical, and pyroelectric data. It is concluded that the ferroelectric transition in Na is of the first order.
- Received 9 February 1970
DOI:https://doi.org/10.1103/PhysRevB.2.2709
©1970 American Physical Society