Targeted hydroxyl fluorination for first-principles design of deep-ultraviolet nonlinear optical crystals: multi-property optimization & chromatic dispersion modulation in Li 2 CsB 7 O 10 F 4

Targeted hydroxyl fluorination in Li 2 CsB 7 O 10 (OH) 4 yields a DUV NLO crystal featuring a 7.33 eV gap, strong SHG (∼1.9 × KDP), and phase-matching at 198.5 nm, breaking the 200 nm barrier.