Terbium Gallium Garnet (TGG) is the rightcrystal material for Farady devices(Rotator and Isolator). The Farady ratatoris made up of a TGG rod contained in a special designed magnet. Thepolarization of a light beam passing through the rotator makes rotation.Thedirection of rotation is only dependent on the direction of the magnetic fieldand not on the direction of propagation of the light beam.The optical isolatorconsists of a 45 degree rotator set between two suitably arrayed polarizerswhich allow a light beam to pass through in one direction only. With acombination of excellent properties, such as large verdet constant,low lightloss, high thermal conductance and high light damage threshold,TGG is theunique material for Farady devices. It is widely used for YAG lasers andTi:sapphire tunable lasers,ring Lasers,etc.
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