Growth, ultraviolet‐visible, vibrational, photoluminescence and second harmonic generation studies of Amaranth and EDTA co‐doped KDP crystals

Abstract

KDP (Potassium dihydrogen phosphate) single crystals were grown from Amaranth dye and EDTA (Ethylenediaminetetraacetic acid disodium salt) mixed KDP solutions by the temperature lowering method and Sankaranarayanan-Ramasamy technique. The molar concentration of EDTA in the solutions was 1\xa0mol%. The Amaranth concentrations were 0.001, 0.005, 0.01, 0.03 and 0.05\xa0mol%. The growth of KDP crystals was oriented in type I and type II phase-matching directions which bring maximum second harmonic generation (SHG) efficiency to the crystals. Optical properties of Amaranth and EDTA co-doped KDP crystals (KAE) were investigated by Ultraviolet-Visible (UV-Vis) spectroscopy, FT-Raman spectroscopy, and photoluminescence. SHG efficiency of the crystals was measured by shining 1064\xa0nm Nd:YAG laser directly into them and receiving output signals. The most important result in the study showed that KAE crystals had SHG efficiency of 1.7 and 2.4 times higher than EDTA doped KDP crystal (KE) and pure KDP crystal respectively. Then second-order nonlinear optical coefficients of these crystals were calculated. The simultaneous doping of two organic substances into KDP crystals has further enhanced their nonlinear optical characteristics.