Patent ID: 7133189

Claim:
A Faraday rotator comprising: a bismuth-substituted rare earth-iron-garnet single-crystal film; and two surfaces formed on the single-crystal film for light transmission through them; wherein the single-crystal film is represented by a chemical formula: Bi 3-x-y R x A y Fe 5-z-w M z B w O 12 wherein R is at least one element selected from a group consisting of rare earth elements and Y; A is at least one element selected from Pb, Ca and Cd; x and y satisfy 1.5<x +y<2.5 and y>0; M is at least one element selected from Ga, Al, Sc and In; B is at least one element selected from Si, Ti, Ge, and Mg; and z and w satisfy 0≦z+w<1.5, and, when y in one of the two surfaces is represented by y 1 and y in the other is represented by y 2 , then y 1 and y 2 satisfy y 2 ≦y 1 ≦2y 2 ; and when w in one of the two surfaces is represented by w 1 and w in the other is represented by w 2 , then w 1 and w 2 satisfy w 2 ≦w 1 ≦2w 2 .