| 摘要 |
PURPOSE:To attain a small-size and light weight further reduce cost, of a device by combining one polarizer with a magnetooptic element which provides polarization on a slanting surface arranged at the complementary angle of a Brewster angle to an optical axis. CONSTITUTION:Light L12 reflected by an end surface of an optical fiber 5 passes through the polarizer 1 in the opposite direction as shown by B to enter the transmission surface 13 of the magnetooptic element 10. The light is influenced therein by an external magnetic field H and its plane of polarization rotates counterclockwise in regard to its optical axis; and the light propagates while reflected repeatedly by a reflecting film 14. Linear polarized light reaching the slanting surface 12 while the plane of polarization rotates by 45 deg. has the plane of polarization rotated by 90 deg. as compared with light in the forward direction shown by A and is reflected by the slanting surface 12 which provides polarization, so almost no light returns to a semiconductor laser 4. This constitution reduces the size, weight and cost of the optical isolator. |
