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The Faraday effect or Faraday rotation, sometimes referred to as the magneto-optic Faraday effect (MOFE), [1] is a physical magneto-optical phenomenon. The Faraday effect causes a polarization rotation which is proportional to the projection of the magnetic field along the direction of the light propagation.
Faraday rotation is a rare example of non-reciprocal optical propagation. Although reciprocity is a basic tenet of electromagnetics, the apparent non-reciprocity in this case is a result of not considering the static magnetic field but only the resulting device.
Optical isolators are different from 1/4 wave plate based isolators [dubious – discuss] [clarification needed] because the Faraday rotator provides non-reciprocal rotation while maintaining linear polarization. That is, the polarization rotation due to the Faraday rotator is always in the same relative direction.
In contrast, the Faraday effect is non-reciprocal, i.e. opposite directions of wave propagation through a Faraday medium will result in clockwise and anti-clockwise polarization rotation from the point of view of an observer. Faraday rotation depends on the propagation direction relative to that of the applied magnetic field.
Kerr rotation and Kerr ellipticity are changes in the polarization of incident light which comes in contact with a gyromagnetic material. Kerr rotation is a rotation in the plane of polarization of transmitted light, and Kerr ellipticity is the ratio of the major to minor axis of the ellipse traced out by elliptically polarized light on the plane through which it propagates.
In a magnetic field, even substances that lack chirality rotate the plane of polarized light, as shown by Michael Faraday. Magnetic optical rotation is known as the Faraday effect, and its wavelength dependence is known as magnetic optical rotatory dispersion. In regions of absorption, magnetic circular dichroism is observable.
ANSI and IEC standard schematic symbol for a circulator (with each waveguide or transmission line port drawn as a single line, rather than as a pair of conductors). In electrical engineering, a circulator is a passive, non-reciprocal three- or four-port device that only allows a microwave or radio-frequency (RF) signal to exit through the port directly after the one it entered.
[3] [4] This behavior means that the devices manufactured with a certain degree of rotation at one wavelength, will produce much less rotation at longer wavelengths. Many Faraday rotators and isolators are adjustable by varying the degree to which the amount of the Faraday rotator material is inserted into the magnetic field of the device. In ...