MAGNETIC GARNET-FILMS PREPARED BY ION-BEAM SPUTTERING AND THEIR APPLICATION TO OPTICAL ISOLATORS

As a 45 degree Faraday rotator of the optical isolator in visible region, highly Bi-substituted iron garnet films prepared by the reactive ion beam sputtering-deposition(RIBS) are investigated. The films both Bi3Fe5O12 and Bi2.5Y0.5Fe5O12 are deposited onto the (111) oriented Gd3Lu2Ga3O12 and Gd3Sc2Ga3O12 garnet substrates. The surface morphology becomes rougher as the film thickness increases approximately over 1.5-mu-m. Two step RIBS growth method and sputtering conditions are examined. A 15 degree Farday rotation angle at a film thickness of 2.3-mu-m (lambda = 633nm) is obtained. Combining the 2.3-mu-m thick RIBS-grown film with a 28-mu-m thick conventional LPE-grown film produced a 45 degree Faraday rotator. The forward and backward losses of the isolator are 4.2 dB and -35 dB respectively.