Strong IR NLO Material Ba₄MGa₄Se₁₀Cl₂: Highly Improved Laser Damage Threshold via Dual Ion Substitution Synergy

Infrared nonlinear optical (IR NLO) materials are the key materials in the modern laser frequency conversion technology that are widely applied in many fields. Yet, the major issue is lacking of high performance materials with large nonlinear susceptibility and high laser damage threshold, which are two correlated and contradictory parameters. Here, the novel dual ion substitution synergy leads to the discovery of Ba₄MGa₄Se₁₀Cl₂ (M = Zn, 1; Cd, 2; Mn, 3; Cu/Ga, 4; Co, 5; and Fe, 6), crystallizing in the tetragonal . Polycrystalline 1–4 exhibits very strong IR second harmonic generations (SHG). (1: 59×; 2: 52×; 4: 39×; and 3: 30× that of IR benchmark NLO material AgGaS₂). Remarkably, the laser‐induced damage threshold of 1 is 143.6 MW cm^–2, roughly 17 times that of benchmark AgGaS₂. These distinguish 1 as a new promising NLO material. In addition, 1, 2, and 4 illustrate the coexistence of NLO and photoluminescence properties. Especially, 3 demonstrate for the first time the coexistence of triple properties (NLO, photoluminescence, and magnetism) in a single crystal structure. The insights of the driving force of the synergetic substitution, SHG origin, and microscopic contributions of the building units open a new route to discovering novel multi‐functional NLO materials.