| 摘要 |
PURPOSE:To realize optical integration without using expensive parts by arranging two optical waveguides, which show unreciprocal characteristics by an external magnetic field, in parallel adjacently to each other on one substrate, and making optical waveguides different in propagation constant before application of the external magnetic field, and setting the coupling length of a direction coupler to a prescribed value. CONSTITUTION:Two waveguides 7 and 8 which are partially formed with magnetooptic materials and show unreciprocal characteristics by the external magnetic field are arranged in parallel adjacently to each other on one substrate 5 to form the directional coupler. Propagation constants of these optical wavegudies 7 and 8 before application of the external magnetic field are different from each other, and a coupling length L of the directional coupler is set to a prescribed value. Power is completely shifted from one to the other of optical waveguides 7 and 8 with respect to a forward wave but is not shifted with respect to a backward wave. Thus, an expensive Farady rotator is not required and adjustment of high precision is made unnecessary, and the optical circulator is formed as one body on the substrate and is suitable for optical integration and is made inexpensive. |
