| 摘要 |
PURPOSE:To obtain an optical isolator which is simple in constitution and has high coupling efficiency to an optical fiber and semiconductor laser by providing two mode selecting parts and rotating the one mode selecting part by 45 deg. with respect to the other, thereby gradually changing the film thickness of the waveguide layer and the width of the waveguide of the mode selecting parts. CONSTITUTION:The mode selecting parts 5 and 6 are connected to both ends of a mode converting part 4. The one 5 of the mode selecting parts is rotated by 45 deg. with the other 6 and is connected to the mode converting part 4. The film thickness of the waveguide layers 9, 10 and the width of the ridge part of the mode selecting parts 5, 6 are gradually changed. The mode converting part 4 is set with the film thickness of a magnetic thin film 2 in such a manner that the propagation constants of the TE and TM modes propagating in the magnetic thin film 2 are equaled by utilizing the double refractions generated in the thin film 2 by the stress arising from a difference in the grating constant between a substrate 1 and the magnetic thin film 2. The constitution of the optical isolator is simplified in this way and the cost is reduced. In addition, the coupling efficiency of light is enhanced and the insertion loss of the optical isolator is lessened. |
