Fabrication and Characterization of Evanescent Semiconductor Optical Isolators with Small Gain Saturation Effect

We report the fabrication and characterization of an evanescent semiconductor optical isolator. The fabricated device exhibited 7.4 dB/mm optical isolation and improved gain saturation characteristics. The effect of the gain saturation on the semiconductor optical isolator was clarified by experimental results and comparison with previously reported propagation characteristics. The demonstrated device is appropriate for monolithically integrated semiconductor optical isolators, which will be useful for all-optical signal processing. (C) 2010 The Japan Society of Applied Physics