Semiconductor Waveguide Optical Isolators Towards Larger Optical Isolation Utilizing Nonreciprocal Phase Shift by Ferromagnetic Co

We theoretically investigated optical isolation in Co-InGaAsP semiconductor active waveguide optical isolators based on a nonreciprocal phase shift. By appropriate design of the waveguide layer structure and ferromagnetic metal, a large alpha parameter can be obtained, and the optical isolation was estimated to be larger than 30 dB in Mach-Zehnder interferometric waveguide optical isolators. The length of the nonreciprocal phase shifting region is as short as 1.3 mm.