Fdk Corporation

Toshiyasu Suzuki

Hirotaka Kawai

Hiromitsu Umezawa

Disclosed is a magneto-optical element material composed of a magnetic garnet single crystal which is small in temperature dependency of a Faraday rotation angle, capable of being formed into a film by the LPE, and significantly small in wavelength dependency of a Faraday rotation angle in a specific composition region defined by. The magneto-optical element material is composed of a magnetic garnet single crystal expressed by a composition formula of R.sub.3-x Bi.sub.x Fe.sub.5-v-w-y Ma.sub.v Mb.sub.w Co.sub.y O.sub.12 where R indicates a rare earth element including yttrium, Ma is a trivalent cationic element, and Mb is a tetravalent cationic element; and x, y, v and w satisfy relationships of 0.6.ltoreq.x.ltoreq.1.9, 0.01.ltoreq.y.ltoreq.0.47, 260y-88x+45.ltoreq.0, 500y-30x+37.ltoreq.0, 0.ltoreq.v.ltoreq.1.0, and 0.ltoreq.w.ltoreq.0.35. The material satisfying the following relationships of 0.01.ltoreq.y.ltoreq.0.28 and 800y-130x+45.ltoreq.0 specifically shows improvement in a wavelength dependency of a Faraday rotation angle. Further disclosed is a Faraday element formed by superimposing an A film on a B film for broadening a usable wavelength band region using difference in wavelength dependency of a Faraday rotation coefficient between both the films A and B. The A film is made, by the LPE, from a Bi-substitution type rare earth-iron garnet single crystal not containing Co and the B film is made, by the LPE, from a rare earth-iron garnet single crystal containing Co.

Magneto-optical element material and Faraday element using the same

Disclosed is a material for a magneto-optical element, which is made of magnetic garnet single crystals being wide in a band width in a 1310 nm band and thereby being capable of coping with the wavelength multiplex communication at the wavelength band, and a Faraday rotator using the same. The material for a magneto-optical element is made of a magnetic garnet having a composition formula expressed by R.sub.3-y-x Sm.sub.y Bi.sub.x Fe.sub.5 O.sub.12, where R is one kind of rare earth elements including yttrium (Y), and 'x' and 'y' are constants defined by 0.3.ltoreq.x.ltoreq.1.9 and 0.4.ltoreq.y.ltoreq.2.7, the magnetic garnet being formed on a non-magnetic substrate by liquid-phase epitaxial growth. R is preferably one of Y, La, Sm and Lu. The Faraday rotator, which is used in a wavelength range of from 1250 to 1370 nm, is formed by superposing a film A made of LPE magnetic garnet single crystals expressed by a composition formula of R1.sub.3-x Bi.sub.x Fe.sub.5-z Z.sub.z O.sub.12, to a film B made of LPE magnetic garnet single crystals expressed by a composition formula of R2.sub.3-y Sm.sub.y Fe.sub.5 O.sub.12, where R1 is one of Al, In of rare earth elements including Y; Z is one of Al, In and Ga; R2 is one kind of rare earth elements including Bi and Y; and 'x', 'y' and 'z' are constants defined by 0.3.ltoreq.x.ltoreq.1.9, 0.5.ltoreq.y.ltoreq.3 and 0.ltoreq.z.ltoreq.0.5.

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Hamamatsu, Japan

Toshiyasu Suzuki