Potassium aluminium borate (K₂Al₂B₂O₇) is an ionic compound composed of potassium ions, aluminium ions, and borate ions. Its crystal form exhibits nonlinear optical properties. The ultraviolet beam at 266 nm can be obtained by fourth harmonic generation (FGH) of 1064 nm Nd:YAG laser radiation through a nonlinear crystal K₂Al₂B₂O₇ (KABO).