Enhanced photorefractive properties of paraelectric potassium-lithium- tantalate-niobate by manganese doping

Paraelectric potassium-lithium-tantalate-niobate, or KLTN, crystals have been grown with two different Mn concentrations: 0.25 and 0.5 mol%. Detailed investigations have been made on the photorefractive (PR) properties of the as-grown crystals by the two-wave mixing technique. High diffraction efficiencies of 90% and 62.5% and PR sensitivities of 1.0 × 10 ^-9E₀ cm² J^-1 and 3.0 × 10 ^-9E₀ cm² J^-1 were achieved for 1.5 mm thick Mn_0.25 : KLTN and Mn_0.5 : KLTN, respectively. The measured two-wave mixing gains for 0.25 mol% and 0.5 mol% reached large values of 27 cm^-1 at the external field of E₀ = 3.4 kV cm ^-1 and of 25 cm^-1 at E₀ = 3.9 kV cm ^-1, respectively. The normalized PR response time under 1 W cm ^-2 illumination is less than 1 s at 532 nm. It is shown that Mn can effectively enhance the PR properties of KLTN which is a very promising ideal material for electroholographic applications.