Refractive index database

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Optical constants of ZBLAN fluoride glass
Gan 1995: n 0.365–3.50 µm

Wavelength: µm

Complex refractive index (n+ik)[ i ]

n   k   LogX   LogY   eV

Derived optical constants

Dispersion formula [ i ]



Room temperature.


F. Gan. Optical properties of fluoride glasses: a review. J. Non-Cryst. Solids 184, 9–20 (1995)


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ZBLAN fluoride glass

ZBLAN is a type of heavy-metal fluoride glass composed primarily of zirconium, barium, lanthanum, aluminum, and sodium fluorides. It is distinguished by its exceptional transmission capabilities in the mid-infrared range, often far superior to that of silica-based glasses. ZBLAN glass is renowned for its low levels of optical scattering, low refractive index variations, and low optical losses, making it an ideal material for fiber-optic applications, especially for those operating in the infrared spectrum. It also boasts a broad transmission window, from the ultraviolet through to the mid-infrared, and is often used in applications like spectroscopy, laser transmission, and sensing where these properties offer distinct advantages. However, ZBLAN can be challenging to manufacture and work with due to its sensitivity to impurities and crystallization. Despite these challenges and its relatively high cost, the unique optical properties of ZBLAN make it indispensable for specialized applications where conventional optical materials fall short.

Typical composition

53% ZrF4, 20% BaF2, 20% NaF, 4% LaF3, 3% AlF3

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Glass is a versatile, amorphous material that has been an essential component in optical technologies for centuries. Comprising mainly of silica along with various additives like soda, lime, or boron, glass can be engineered to exhibit a wide range of optical properties, such as refractive indices and dispersion characteristics. In the optical industry, specialized types of glass like crown, flint, and extra-low dispersion (ED) glasses are used for manufacturing lenses, prisms, and other optical elements. These glasses are precisely formulated to offer specific properties, such as low chromatic aberration or high light transmittance across different spectral ranges. Glass can also be coated with thin layers of materials like anti-reflective coatings to enhance its optical performance. More recently, advances in photonics and nanotechnology have led to the development of innovative glass types, such as photonic crystal and metamaterial glasses, which exhibit unique light-manipulating properties. It is crucial to note that the optical properties of glass, including its refractive index, can vary depending on its composition and temperature, making it important to consult specific data for particular applications. Overall, glass remains a foundational material in optics, its wide applicability owed to its tunable properties and general robustness.

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