Lithium niobate

Lithium niobate (LiNbO₃) is a ferroelectric, piezoelectric crystal with strong electro-optic and nonlinear optical properties. These properties make it useful for controlling light and converting electrical signals into mechanical or optical responses.

Lithium niobate modulator: An electro-optic device that changes a light beam’s phase or intensity by applying an electric field to lithium niobate. It uses the crystal’s electro-optic effect to encode information onto optical signals.
Pockels effect: A linear electro-optic effect in which an applied electric field changes a material’s refractive index. This effect lets lithium niobate convert voltage changes into rapid optical modulation.
Perovskite structure: A crystal structure characterized by the general formula ABX₃ and a framework of corner-sharing BX₆ octahedra. Lithium niobate has a related, distorted structure that helps explain its polar properties.
Lithium tantalate: A ferroelectric oxide crystal, LiTaO₃, with electro-optic, piezoelectric, and nonlinear optical properties. It shares many device roles with lithium niobate but has different material constants and processing characteristics.
Surface acoustic wave filter: An electronic filter that uses surface acoustic waves on a piezoelectric substrate to select signal frequencies. Lithium niobate’s piezoelectricity makes it a substrate for compact, high-frequency filters.
Second-harmonic generation: A nonlinear optical process that converts two photons at one frequency into a photon at twice that frequency. Lithium niobate’s nonlinear polarization supports this form of frequency doubling.
Crystal system: A classification of crystals by the symmetry and geometry of their unit cells. Lithium niobate’s trigonal symmetry constrains its optical and electrical tensor properties.
Gallium arsenide: A III–V semiconductor used in high-speed electronics, infrared optoelectronics, and photonic devices. It offers a different route to integrated electro-optics, with semiconductor fabrication and band-structure advantages.
Optical frequency conversion: The transformation of light from one frequency to another through interactions in a nonlinear optical medium. Lithium niobate’s strong nonlinear response enables efficient conversion between optical frequencies.
Ferroelectricity: A property of certain crystals whose spontaneous electric polarization can be reversed by an applied electric field. Lithium niobate’s switchable polarization enables domain engineering and poling.

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