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Various planar waveguides are fabricated by indiffussion of one or two titanium layers into y-cut LiNbO, substrates. The effective indices of guided TE-and TM-modes are measured for red, green, and blue light. The refractive index profiles are reconstructed by a new reliable inverse WKB procedure. Despite of widely differing profiles there is, for each wavelength, a one to one relationship between the changes An, of the ordinary and An, of the extraordinary refractive index. For low and for high refractive index changes An, and An, grow proportionally, but their ratios differ appreciably. The results support recent findings that the LiNb0,:Ti system exists in two distinct phases. Verschiedene planare Wellenleiter werden durch Eindiffusion von einer oder zwei Titanschichten in y-geschnittene LiNb0,-Substrate hergestellt. Die effektiven Indizes der gefuhrten TEund TM-Moden werden fur rotes, griines und blaues Licht gemessen. Mit einem neuen zuverlassigen inversen WKB-Verfahren werden die Brechungsindexprofile rekonstruiert. Trotz stark unterschiedlicher Profile existiert fur jede Wellenlange eine eins-zu-eins-Beziehung zwischen den Anderungen An,, des ordentlichen und An, des aul3erordentlichen Brechungsindexes. Fur niedrige und hohe Brechungsindexanderungen wachsen An, und An, proportional, jedoch unterscheiden sich ihre Verhlltnisse betrachtlich. Die Ergebnisse bestatigen die kurzlich gemachte Entdeckung, daB das LiNbO, :Ti-System in zwei unterschiedlichen Phasen existiert.

Calculations are presented describing a novel optical isolator which works by complete TE(0)-TM(0) mode conversion in magnetic garnet films caused by stress-induced optical anisotropy (50%) and by Faraday rotation (50%). These conversions take place along two different, perpendicular light paths in the same crystal that are connected by an integrated mirror. Possible tolerances of the film parameters are given so that a 30-dB isolation is still guaranteed.

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