Co-doping effect of Amaranth and EDTA on bulk growth, optical, structural properties and second harmonic generation of KDP crystals grown by Sankaranarayanan-Ramasamy (SR) technique

KDP (Potassium dihydrogen phosphate) single crystals co-doped with Amaranth dye and EDTA (Ethylenediaminetetraacetic acid disodium salt) with concentrations of 0.005 mol% and 1 mol% respectively in the solution were grown from seeds by the method of temperature reduction and Sankaranarayanan-Ramasamy (SR) technique. The seeds were mounted vertically and in a direction of 59° from the vertical. The latter orientation of the seed made second harmonic generation (SHG) efficiency of KDP crystal with the 1064 nm laser reach its maximum value. Bulk growth, optical, and structural properties of the crystals were assessed by UV–Vis spectroscopy, X-ray diffraction (XRD) analysis, and photoluminescence. The elemental composition of crystals was also determined by Energy-dispersive X-ray (EDX) spectroscopy. Amaranth and EDTA additives have improved the SHG performance of pure KDP crystals by up to 168%, which probably could not be achieved by doping either with Amaranth or EDTA. Finally, three different parts of the crystal rods grown by SR technique were not homogeneous in the optical, structural properties and the degree of being dyed. •Amaranth and EDTA co-doped KDP single crystals (KAE) were successfully grown by the temperature lowering method and Sankaranarayanan-Ramasamy technique.•The growth of KDP crystals was oriented in [001] direction and type II phase-matching direction which brings maximum second harmonic generation (SHG) efficiency to the crystal.•Optical characteristics differed in three different parts (the base, the middle, and the head) of the KAE single crystal.•KAE crystals had SHG efficiency of 2.2 and 2.6 times higher than EDTA doped KDP crystal (KE) and pure KDP crystal respectively.