Influence of stoichiometry on the optical properties of potassium lithium niobate crystals

Two kinds of potassium lithium niobate (KLN) crystals with different crystal composition have been grown by the Czochralski method from different starting compositions. We report optical spectra of the crystals in the UV-VIS and IR region and their electro-optic effects. The results prove that measurements of the absorption edge and the OH vibration modes are sensitive method for characterizing the crystal composition of the KLN crystals. We also observe that the effective electro-optic coefficient (r(c)) of the nearly stoichiometric KLN crystals is much larger than that of the non-stoichiometric KLN crystals with an almost one order of magnitude.