[en] Fluoride materials display specific properties applicable for use as active and passive optical elements for advanced laser programs. Generally, these materials exhibit low values of n₂ and high ultraviolet transmission. Nd:YLF is a very promising laser fusion oscillator element operating in conjunction with phosphate and fluoroberyllate systems. New materials possessing high concentrations of terbium and cerium - KTb₃F₁₀, RbTb₃F₁₀ and potassium cerium compounds, display high magneto-optical rotatory power, high Verdet's constant, for use as Faraday rotators. Nd:YLF, operating at 1.047 μm or 1.053 μm has been identified as the most promising oscillator material for phosphate and fluoroberyllate systems. The new materials investigation included crystal growth and phase study of KTb₃F₁₀. KTb₃F₁₀ displays one of the highest figures of merit of any known material. Preliminary growth studies of other potential rotator materials included the RbF-Tb₃F₁₀ and the KF-CeF₃ systems. Compounds of both systems are expected to display high Verdet's constants