Refractive index database

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Optical constants of KNbO3 (Potassium niobate)
Umemura et al. 1999: n(β) 0.40–5.3 µm

Wavelength: µm

Complex refractive index (n+ik)[ i ]

n   k   LogX   LogY   eV

Derived optical constants

Dispersion formula [ i ]



nβ; 22 °C.


N. Umemura, K. Yoshida, and K. Kato. Phase-matching properties of KNbO3 in the mid-infrared, Appl Opt. 38, 991-994 (1999)


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Potassium niobate, KNbO3

Potassium niobate (KNbO3) is a ferroelectric crystal with notable nonlinear optical properties. It is widely used in a range of optical applications, including frequency doubling, optical parametric oscillation, and electro-optic modulation. Due to its high damage threshold and broad phase-matching capabilities, it has become a material of choice for nonlinear optical applications in the visible and near-infrared spectral ranges. KNbO3 is also known for its photorefractive properties, which are exploited in data storage and holography. However, the material is sensitive to moisture and can degrade over time if not properly stored, requiring a controlled environment for long-term use.