Optical Isolator - Theory

Theory

The main component of the optical isolator is the Faraday rotator. The magnetic field, , applied to the Faraday rotator causes a rotation in the polarization of the light due to the Faraday effect. The angle of rotation, is given by,

,

where, is the Verdet constant of the material (amorphous or crystalline; solid, liquid, or gaseous) of which the rotator is made, and is the length of the rotator. This is shown in Figure 2. Specifically for an optical isolator, the values are chosen to give a rotation of 45°.

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