Dielectric and electro-optic properties of potassium-sodium-barium niobate crystals: second-harmonic generation

Crystals of K_xNa_1–xBa₂Nb₅O₁₅ with different amounts of potassium (x=0–0.6) were grown and investigated. The Curie, phase-transition, and phase-matching (in the generation of the second harmonic of λ=1.15 μ radiation) temperatures and the half-wave voltage were determined as a function of x. The temperature dependences of the permittivity ε_z and its reciprocal 1/ε_z were determined in the vicinity of the Curie temperature for different values of x. Introduction of potassium into the NaBa₂Nb₅O₁₅ lattice improved the optical quality of crystals.