Silicon-based integrated polarization-independent magneto-optical isolator

As indispensable components in optical communication systems, isolators are used to ensure the stability of the system by blocking the reflected lights. Because of the randomness of the reflected light state in a complex optical circuit, polarization-independent isolators are also needed; however, the silicon-based integrated isolators reported so far still cannot meet this requirement. In this paper, we propose a silicon-based waveguide-integrated polarization-independent magneto-optical isolator. After processing by a CMOS compatible process on the silicon platform, isolation ratios of 20 dB and 12 dB, as well as insertion losses of 4.6 dB and 8.2 dB, were measured corresponding to TE- and TM-polarized input, respectively. This isolator is expected to be employed in polarization multiplexing systems to further increase the integration density.