Optical studies of potassium acid phthalate single crystals added with amino acids

Potassium acid phthalate (KAP) is a promising optical material with high NLO efficiency. Pure and amino acid (aspartic acid/l-citrulline) added KAP crystals were grown by the slow evaporation method at 32 °C and characterized. The elemental, FT-IR spectral and FT-Raman spectral analyses confirm the entry of amino acid molecules in the KAP crystal matrix in the case of amino acid added KAP single crystals. The UV–vis-NIR and second harmonic generation (SHG) efficiency measurements indicate an increase of optical transmittance and SHG efficiency due to amino acid addition. The photoluminescence (PL) measurement indicates that the amino acid addition significantly tunes the PL yield of KAP crystal.