Refractive index database

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Optical constants of CRYSTALS
Sapphire (Al2O3)

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
direction: o


Synthetic sapphire, Ordinary ray (o), 20 °C


1) I. H. Malitson and M. J. Dodge. Refractive Index and Birefringence of Synthetic Sapphire, J. Opt. Soc. Am. 62, 1405 (1972)
2) M. J. Dodge, "Refractive Index" in Handbook of Laser Science and Technology, Volume IV, Optical Materials: Part 2, CRC Press, Boca Raton, 1986, p. 30
* Ref. 1 is a talk abstract in a conference program; Ref. 2 provides a dispersion formula


[Expressions for n]   [CSV - comma separated]   [TXT - tab separated]   [Full database record]


Aluminium sesquioxide, Al2O3

Al2O3, commonly known as alumina or aluminum oxide, is a ceramic material that has a wide range of applications due to its excellent mechanical and optical properties. This compound crystallizes in various phases, the most stable and common of which is the corundum structure. Alumina is transparent in the ultraviolet to the infrared range, making it a versatile material for a variety of optical applications such as protective windows and lenses. It has a high refractive index and is also known for its strong dielectric properties. One of the key attributes of Al2O3 is its remarkable thermal stability and resistance to chemical attack, which makes it suitable for harsh environment applications. Furthermore, the material has been investigated for its nonlinear optical characteristics, although it is generally less efficient in this regard compared to other nonlinear optical materials. Alumina can also serve as a substrate material for thin-film optical coatings. In summary, Al2O3 is a robust and multifunctional material that is extensively studied for its enduring relevance in both traditional and advanced optical systems.

Other names

  • Alumina
  • Aluminium oxide
  • Aloxite
  • Aluminium oxide (α)
  • Aluminium(III) oxide
  • Dialuminium trioxide


  • Corundum


  • Sapphire
  • Ruby

External links


Crystals are highly ordered, periodic structures that offer a range of unique optical properties unattainable with amorphous materials like glass. Comprising atoms, ions, or molecules arranged in a repeating lattice structure, crystals can be engineered or selected to exhibit specific characteristics such as high refractive indices, low dispersion, and even nonlinear optical behavior. Commonly used optical crystals include quartz, sapphire, and various synthetic materials like potassium titanyl phosphate (KTP) and lithium niobate (LiNbO3). These materials are often used in applications that require high levels of precision and performance, such as in laser systems, optoelectronic devices, and frequency converters. Crystals can also demonstrate phenomena like birefringence, where the refractive index varies depending on the polarization and direction of light, making them invaluable in specialized optical components like waveplates and polarizers. Advanced crystal structures like photonic and plasmonic crystals can manipulate light at the nanoscale, offering avenues for research and application in areas like integrated optics and quantum computing. It's important to note that the optical properties of crystals, such as their refractive index and absorption coefficients, can be highly anisotropic and dependent on the crystal orientation. Therefore, specific data must be consulted for precise applications. Overall, crystals offer a broad palette of options for manipulating light, making them integral to both classical and cutting-edge optical technologies.

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