ZBLAN is the most stable, and consequently the most used, fluoride glass, a subcategory of the heavy metal fluoride glass (HMFG) group. Typically its composition is 53% ZrF₄, 20% BaF₂, 4% LaF₃, 3% AlF₃ and 20% NaF. ZBLAN is not a single material but rather has a spectrum of compositions, many of which are still untried. The biggest library in the world of ZBLAN glass compositions is currently owned by Le Verre Fluore, the oldest company working on HMFG technology. Other current ZBLAN fiber manufacturers are Thorlabs and KDD Fiberlabs. Hafnium fluoride is chemically similar to zirconium fluoride, and is sometimes used in place of it.

ZBLAN glass has a broad optical transmission window extending from 0.22 micrometers in the UV to 7 micrometers in the infrared. ZBLAN has low refractive index (about 1.5), a relatively low glass transition temperature (T_g) of 260–300 °C, low dispersion and a low and negative temperature dependence of refractive index dn/dT.

The first fluorozirconate glass was a serendipitous discovery in March 1974 by the Poulain brothers and their co-workers at the University of Rennes in France.

While looking for new crystalline complex fluorides, they obtained unexpected pieces of glass. In a first step, these glasses were investigated for spectroscopic purposes.

Glass formation was studied in the ZrF₄-BaF₂-NaF ternary system while the fluorescence of neodymium was characterized in quaternary ZrF₄-BaF₂-NaF-NdF₃ bulk samples. The chemical composition of this original glass was very close to that of the classical ZBLAN, on the basis of a simple La/Nd substitution.

Further experimental work led to major advances. First, ammonium bifluoride processing replaced the initial preparation method based on heat treatment of anhydrous fluorides in a metallic sealed tube. This process was already used by K. H. Sun, a pioneer of beryllium fluoride glasses. It offers significant advantages: preparation is implemented at room atmosphere in long platinum crucibles, zirconium oxide can be used as a starting material instead of pure ZrF₄, synthesis time is reduced from 15 hours to less than one hour, and larger samples are obtained. One of the problems encountered was the devitrification tendency upon cooling the melt.

The second breakthrough was the discovery of the stabilizing effect of aluminum fluoride in fluorozirconate glasses. The initial systems were fluorozirconates with ZrF₄ as the primary constituent (>50 mol%), BaF₂ main modifier (>30 mol%) and other metal fluorides LaF₃, AlF₃ added as tertiary constituents, to increase glass stability or improve other glass properties. Various pseudo-ternary systems were investigated at 4 mol% AlF₃, leading to the definition of 7 stable glasses, such as ZBNA, ZBLA, ZBYA, ZBCA that could be cast as multi-kilogram bulk samples and resulted later in the classical ZBLAN glass composition that combines ZBNA and ZBLA.

Further development on preparation method, scale-up, improvements of the manufacturing process, material stability and formulations was largely motivated by the experiments in French telecom at that time that found that intrinsic absorption for ZBLAN fibers was quite low (~10 dB/km) which could lead to an ultra-low optical loss solution in the mid-infrared. Such optical fibers could then become an excellent technical solution for a variety of systems for telecommunications, sensing and other applications.