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Two interesting effects have been experimentally demonstrated for the first time: (1) simultaneous reciprocal and nonreciprocal mode conversion to achieve an isolation effect and (2) magneto-optic switching between guided and radiation modes. These effects were observed in connection with the construction of a previously proposed thin-film optical isolator. The isolator consists of a piece of LiNbO3 placed on top of a thin film of yttrium ion garnet (YIG) with a selenium layer to avoid optical contact problems. The isolator, which is 1 cm long, exhibited 10 dB of isolation at λ = 1.15 μm. The observed isolation was better than theoretical predictions and a mysterious isolation direction dependence on mode order was observed. Although the device had 10 dB of insertion loss and required a magnetic field of 40 Oe, with a slight change in wavelength and film composition, it should be possible to reduce the insertion loss and field required to under 1 dB and 0.1 Oe, respectively. These characteristics combined with broad tolerances on film thickness and the length of the isolation region, broadband operation (from λ = 1.1 to 4.5 μm), and easy construction and adjustment make the isolator very attractive for use in integrated optics.

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The relevant phase equilibrium data necessary to grow garnet films containing divalent and tetravalent ions by liquid phase epitaxy are presented. The effects of melt composition on film magnetic properties and film composition are presented as is the influence of growth kinetics on the film magnetic parameters. Work on the false(Y,normalSm,normalCa)3false(normalGe,normalFe)5O12 system is stressed. A coupled distribution coefficient is defined which adequately describes the Ca2+‐Ge4+substitution. The effect of melt depletion on magnetic properties is discussed and data presented to indicate the magnitude of the effect observed in the false(Y,normalSm,normalCa)3false(normalGe,normalFe)5O12 system. An example of the propagation characteristics observed in the false(Y,normalSm,normalCa)3false(normalGe,normalFe)5O12 system is also shown. A technique for controlling the temperature dependence of the collapse field in LPE films is presented. The use of Lu3+ as both a dodecahedral and octahedral substituent is shown to lead to a system flexible enough to meet most of the present device requirements.

Recent advances in ion implantation