Electro-optic properties of the organic salt 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate

We show that the organic salt 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate (DAST) is a very interesting material for electro-optic applications in the near infrared. The electro-optic coefficients, namely r₁₁₁, r₂₂₁, r₃₃₁, r₁₁₃, r₂₂₃, and r₃₃₃, were determined in the spectral range of 700 up to 1535 nm using optical samples cut from large high quality bulk crystals. DAST combines large electro-optic coefficients, e.g., r₁₁₁=77±8 Pm/V at λ=800 nm and r₁₁₁=47±8 pm/V at λ=1535 nm, with low dielectric constants, e.g., ε₁=5.2±0.4. This combination leads to large polarization-optical coefficients.