Electro-optic effect

The electro-optic effect is a change in a material’s optical properties caused by an applied electric field. It enables control of light’s phase, polarization, or intensity using voltage.

Pockels effect: A change in a material’s refractive index that is proportional to the applied electric field. This linear electro-optic response occurs in materials without inversion symmetry.
Electro-optic modulator: A device that uses an electric field to control a light wave’s phase, polarization, or intensity. It is the central device application of field-induced optical change.
Birefringence: The dependence of a material’s refractive index on light polarization and propagation direction. An electric field can change birefringence and thereby alter a beam’s polarization.
Magneto-optic effect: A change in a material’s optical properties caused by a magnetic field. It is the magnetic-field counterpart to the electric-field response.
Kerr effect: A change in refractive index proportional to the square of an applied electric field. This quadratic response can occur even when a material lacks the symmetry needed for the Pockels effect.
Mach–Zehnder modulator: An interferometric optical modulator that varies the relative phase of light in two paths. Electro-optic phase shifts in its arms convert voltage into output intensity.
Crystal class: One of 32 groups describing the symmetry operations of a crystal’s point structure. Crystal class determines whether tensor components supporting a linear response can exist.
Acousto-optic effect: A change in a material’s optical properties caused by sound-induced strain or density variation. It controls light through acoustic waves rather than an applied electric field.
Refractive index: A dimensionless measure of how much light slows and bends in a material. Electric fields alter this optical property in the most familiar electro-optic response.
Lithium niobate: A ferroelectric crystal with strong electro-optic, piezoelectric, and nonlinear optical properties. Its strong Pockels response makes it a leading material for modulators.

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