Faraday's rotator and optical isolator

Abstract

A Faraday's rotator comprises a magnetic crystal which has a composition represented by the following compositional formula: (Tb.sub.1-(a+b+c+d) Ln.sup.1.sub.a Ln.sup.2.sub.b Bi.sub.c M.sup.1.sub.d).sub.3 (Fe.sub.1-e M.sup.2.sub.e).sub.5 O.sub.12, has a lattice constant of 12.383.+-.0.006 .ANG. and is grown through the liquid phase epitaxial growth technique. In the foregoing formula, Ln.sup.1 is at least one element selected from the group consisting of Yb, Lu and Tm; Ln.sup.2 is at least one member selected from the group consisting of rare earth elements except for Yb, Lu, Tm and Tb; M.sup.1 is at least one element selected from the group consisting of Ca, Mg and Sr; M.sup.2 is at least one element selected from the group consisting of Al, Ga, Ti, Si and Ge; 0.2.ltoreq.a.ltoreq.0.6, 0.ltoreq.b.ltoreq.0.3, 0 <c.ltoreq.0.16, 0<d.ltoreq.0.02 and 0<e.ltoreq.0.1. Another Faraday's rotator comprises a magnetic crystal having a composition represented by the following compositional formula: (Tb.sub.1-(a+b+c+d+f) Ln.sup.1.sub.a Ln.sup.2.sub.b Bi.sub.c M.sup.2.sub. e).sub.5 O.sub.12, wherein Ln.sup.1, M.sup.1, M.sup.2, a, b, c and e are the same as those defined above; Ln.sup.2 is a member selected from the group consisting of rare earth elements except for Yb, Lu, Tm, Tb and Eu; 0.ltoreq.d.ltoreq.0.02 and 0<f.ltoreq.0.2. An optical isolator is provided with such a Faraday's rotator in the interior thereof.

Dependencies are inferred from the claim text.