At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

American Telephone and Telegraph, Co.

Vincent J Fratello

Charles D Brandle, Jr

Steven J Licht

Joseph Shmulovich

Raymond Wolfe

Eliezer M Rabinovich

Lars C Luther

Alejandro J Valentino

Ralph S Jameson

Susan E Slusky

An optical isolator is disclosed which comprises a Faraday rotator disposed between a pair of polarization selective elements (e.g., linear polarizers, birefringent wedges, birefringent plates, etc.). Improvement in isolation stability as a function of variations in temperature and/or signal wavelength are achieved in accordance with the teachings of the present invention by utilizing a Faraday device with a rotation .theta. less than the conventional 45.degree.. A linear reduction in .theta., while resulting in a some signal loss, provides a linear increase in both temperature and wavelength stability.

Optical isolator with improved stabiity

High magnetic anisotropy is achieved in bismuth-iron garnet materials which comprise a significant amount of europium, samarium, or terbium. Such materials may be made in the form of epitaxial layers grown on a nonmagnetic substrate, e.g., in the manufacture of magnetic bubble devices. On account of significant Faraday rotation, such materials may also be used in magnetic-optical devices.

Bismuth-iron garnets with large growth-induced magnetic anisotropy

Apparatus according to the invention comprises magneto-optic isolator means that utilize a novel temperature compensation scheme. The scheme involves the use of a composite magneto-optic member that comprises a first single crystal garnet layer that does not have a compensation temperature within the operating temperature range of the isolator, and further comprises a single crystal garnet layer (the 'compensation point layer') that has a compensation temperature within the operating temperature range of the isolator. Exemplarily, the compensation point layer has composition (Bi.sub.0.8; Tb.sub.1.1 Gd.sub.1.1)(Fe.sub.4.6 Ga.sub.0.4)O.sub.12, and is grown on an CMZ:GGG substrate, and the first garnet layer has composition (Bi.sub.1.2 Tb.sub.1.8)(Fe.sub.4.6 Ga.sub.0.4)O.sub.12 and is grown on the compensation point layer. The novel temperature compensation scheme can result in isolators having improved extinction ratio with relatively small additional path length in the magneto-optic material.

Apparatus comprising a magneto-optic isolator utilizing a garnet layer

A sol-gel procedure is described for making display devices with luminescent films. The procedure typically involves hydrolysis and polymerization of an organometallic compound together with selected luminescent ions, and coating of a substrate and then heat treatment to form a polycrystalline layer. The procedure is particularly useful for making cathode ray tubes, expecially those for high power operation because of the excellent luminescence characteristics obtained, good thermal contact from the luminescent layer to faceplate and low cost of the procedure. Also described are the devices obtained which exhibit a layer of complex oxide with network structure much like the corresponding bulk compound.

Sol gel method for forming thin luminescent films

The congruently melting composition of gadolinium scandium gallium garnet comprises

Growth of congruently melting gadolinium scandium gallium garnet

Crystals of neodymium and praseodymium iron garnet materials have Faraday rotation which render such materials suitable for use, e.g., as antireciprocal components in optical devices and communications systems. These materials can be made by liquid-phase epitaxy on a substrate having suitable lattice parameters, deposition being carried out at relatively low melt temperatures.

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New Providence, NJ, United States of America

Vincent J Fratello