Faraday effect

The Faraday effect is the rotation of polarized light’s plane of polarization as it travels through a material in a magnetic field parallel to its direction of travel. The rotation reverses when the magnetic field reverses and is nonreciprocal, so it can enable optical isolation.

Magneto-optic effect: A change in a material’s optical properties caused by a magnetic field. The Faraday effect is a specific magneto-optic response.
Optical isolator: A device that transmits light preferentially in one direction while suppressing reverse transmission. Its polarization rotation exploits Faraday nonreciprocity to block reflected light.
Michael Faraday: English experimental physicist and chemist whose discoveries include electromagnetic induction and the Faraday effect. He discovered optical rotation by a magnetic field in 1845.
Polarization (waves): The orientation and evolution of oscillations in a transverse wave. The effect changes the orientation of light’s linear polarization.
Circular birefringence: A difference in refractive index for left- and right-circularly polarized light. The unequal phase speeds of circular components produce the observed rotation.
Faraday rotator: An optical component that rotates polarization through magneto-optic material in a magnetic field. It is the direct device implementation of the effect.
Faraday's 1845 experiment: Michael Faraday’s experiment showing that a magnetic field can rotate polarized light in glass. It established the effect through a direct optical experiment.
Linear polarization: A state of light in which the electric field oscillates along a fixed transverse direction. The effect is commonly observed as rotation of this polarization direction.
Magnetic circular dichroism: A magnetic-field-dependent difference in absorption of left- and right-circularly polarized light. It is a related magneto-optic effect that changes polarization through differential absorption.
Magneto-optic Kerr effect: A magnetic-field-dependent change in the polarization of light reflected from a material. It probes magnetism through reflected light rather than transmission rotation.

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