Optimizing growth, linear and 3rd order nonlinear optical traits of potassium aluminium sulfate (KAS) crystal by tuning pH for photonic device applications

Grown crystals, optical transparency and z-scan plots in open and close aperture conditions of KAS. [Display omitted] •Novel pH dependent crystal growth of KAS was done.•PXRD confirmed improved crystallinity with decrease in pH.•Optical transmittance enhanced with decrease in pH.•3rd order nonlinear optical properties were tuned by change in pH. This investigation is first to report the optimized crystal growth of potassium aluminium sulfate (KAS) at different pH. The well-defined single KAS crystals have been grown at pH 3, 5 and 7 engaging the slow evaporation process. Crystal structure and lattice parameters of grown KAS crystals have been determined using the powder X-ray diffraction technique. The impact of pH on optical transparency of KAS crystal is studied within 200–1000 nm through UV–visible optical analysis. He-Ne laser assisted Z-scan method is used to analyse third order nonlinear optical (TONLO) attributes of KAS crystal grown at alike pH. TONLO phase modification in refraction of grown crystals is inferred by Z-scan in close aperture configuration while the nonlinear absorption nature was sightseen by open orifice Z-scan. The Z-scan data has been used for comparative evaluation of TONLO refraction (n2), susceptibility (χ3) and absorption (β) coefficient of KAS crystals.