Influence of citric acid on optical properties of unidirectional grown potassium dihydrogen phosphate crystals

The main aim of the present study is to improve the laser frequency-doubling performance of potassium dihydrogen phosphate KDP single crystal by citric acid (CA) additive. CA-doped KDP crystals were grown unidirectionally in aqueous solutions by the temperature reduction method. CA molar percentage concentrations were 0.01, 0.05, 0.1, 0.5, and 1%, respectively. KDP seed crystals were tilted at angles of 41 degrees and 59 degrees from the vertical. These two values were derived from the phase-matching condition of second harmonic generation (SHG) in a KDP crystal corresponding to the 1064 nm laser. The presence of CA in the finished single crystals was demonstrated first by energy-dispersive X-ray spectroscopy. The effect of CA concentration on structural perfection, molecular vibration, optical transmission, and SHG efficiency of KDP crystals was investigated by X-ray diffraction analysis, Raman spectroscopy, ultraviolet-visible spectroscopy, and SHG measurement, respectively. The two best CA-doped KDP crystal samples, which corresponded to type I and type II phase-matching, respectively, gave a 1064 to 532 nm conversion efficiency 2.6 and 1.8 times higher than pure KDP ones. CA was shown to be a better candidate for insertion into a KDP crystal than other hydroxyl compounds and other carboxylic acids that have been reported.Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Author 1 Given name: [Vinh Trung] Last name [Phan], Author 2 Given name: [Phat Thanh Nhan] Last name [Do] Also, kindly confirm the details in the metadata are correct.I confirm that the author names are correct.