Nondegenerate two-wave interaction in a barium sodium niobate crystal

An experimental investigation was made of the formation of a static hologram by difference-frequency beams (Ω = ω₁ – ω₂ = 2π · 50 Hz) in an alternating external field E₀ cos(Ωt) in an undoped Ba₂NaNb₅O₁₅ crystal at λ = 0.63 μm (He–Ne laser). The dependence of the diffraction efficiency on the spatial frequency of the grating was studied. A qualitative agreement was achieved with theoretical results allowing for the influence of a secondary grating.