Magneto-optics: It is the optical activity in a homogeneous medium in the presence of a magnetic field. In physics, the Faraday effect or Faraday rotation is an interaction between light and a magnetic field. The rotation of the plane of polarization is proportional to the intensity of the component of the magnetic field in the direction of the beam of light. The angle of rotation of the polarization-plane of plane polarized light through a transparent material is found to be a linear function of the product of the mean flux-density and the length of the optical medium. The factor of proportionality is known as Verdet's constant.

The red and green diode lasers (650nm, 530nm, respectively) are used for this experiment. The sample is placed between two linear polarizers. A photodetector is placed at the end of the unit to measure the intensity as a function of the analyzer angle q for a full rotation.

Optical isolators based on Faraday’s effect have important applications in telecommunications preventing reflected signals on fiber optic cables from producing unwanted signals. Isolators are important when lasers are used because reflected light can cause havoc with the operation of the laser itself.