It is yet another object of the present invention to provide a Faraday isolator which does not exhibit transverse heat gradients. It is another object of the present invention to provide a Faraday isolator which is reflective. It is an object of the present invention to provide a Faraday isolator which is capable of handling high energy light beams. It is therefore desirable to have a Faraday isolator which is capable of handling high energy light beams without experiencing significant beam degradation due to heating effects. A second reason is that heat removal from the edges of a Faraday rotator still produces the undesirable thermal gradients in a transverse direction. One reason is that only a small percentage of the total area of a Faraday rotator is located on its edges. For two reasons this led to undesirable effects. However, since most Faraday rotators are transmissive, the only cooling possible was that which could be accomplished by cooling the edges of the Faraday rotator. In the past, Faraday rotators have been cooled. When a Faraday rotator is used with high optical powers (i.e., over 10 watts), the resulting degradation in optical beam quality due to Faraday rotator heating, becomes unacceptable. This heating effect results in thermal gradients in the Faraday rotator, producing a "smearing" of the polarization angle rotation. When dealing with relatively low energy optical beams, a Faraday rotator experiences a modest heating effect. Since the Faraday effect is reversible, the light can be reflected back through the Faraday rotator after the first traversal, doubling the rotation of the polarization angle. Accordingly, to attain a predetermined angular rotation, with a fixed magnetic field, the length of the Faraday rotator must be appropriately adjusted. The magnitude of the angle is dependent upon the length of the Faraday rotator and the magnitude of the magnetic field it imposes. The Faraday effect rotates the plane of polarization of linearly polarized light through an angle. An important component of the optical isolator is a Faraday rotator, which exhibits the Faraday effect. BACKGROUND OF THE INVENTIONįaraday isolators have long been used for the purpose of allowing a light beam to be transmitted in one direction with low loss while highly attenuating a beam traveling through it in the opposite direction. This invention relates to optical Faraday isolators, and more particularly, to optical Faraday isolators capable of handling high average power.
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