Refractive index database

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Optical constants of Fused silica (fused quartz)
Malitson 1965: n 0.21–3.71 µm

Wavelength: µm

Complex refractive index (n+ik)[ i ]

n   k   LogX   LogY   eV

Derived optical constants

Dispersion formula [ i ]


Conditions & Spec sheet

n_is_absolute: false
wavelength_is_vacuum: false
temperature: 20 °C


Fused silica, 20 °C


1) I. H. Malitson. Interspecimen comparison of the refractive index of fused silica, J. Opt. Soc. Am. 55, 1205-1208 (1965)
2) C. Z. Tan. Determination of refractive index of silica glass for infrared wavelengths by IR spectroscopy, J. Non-Cryst. Solids 223, 158-163 (1998)
* Sellmeier formula is reported in Ref. 1 for the 0.21-3.71 μm wavelength range. Ref. 2 verifies the validity of the formula up to 6.7 μm.


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Fused silica

Fused silica is a high-purity form of silicon dioxide (SiO2), known for its exceptional thermal stability, low thermal expansion, and high resistance to chemical corrosion. It is often used in applications requiring superior optical transmission over a wide spectral range, from ultraviolet (UV) to infrared (IR). Fused silica is made by melting high-purity silica at extremely high temperatures, resulting in a material that is both optically clear and highly homogeneous. These properties make it an ideal choice for a variety of demanding applications such as UV optics, semiconductor manufacturing, and high-power laser systems. Furthermore, its low coefficient of thermal expansion makes it highly stable under fluctuating temperature conditions, an essential quality for precision optical components. Overall, fused silica's unique set of properties, including its purity, thermal stability, and broad transmission range, make it a cornerstone material in high-performance optical systems.

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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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