Significant enhancement of magneto-optical effect in one-dimensional photonic crystals with magnetized epsilon-near-zero defect

Nonreciprocal (NOR) transmission with magneto-optical materials plays a critical role in a broad range of applications, such as optical isolation, all-optical signal processing, and integrated photonic circuits. The underlying mechanism is that a static magnetic field can break the time-reversal symmetry in the presence of magneto-optical materials. However, the typical NOR devices usually need a large size because the weak magneto-optical activity of materials. Here, our theoretical investigations show that the NOR transmission can be obtained in the one-dimensional photonic crystal with a magnetized epsilon-near-zero (ENZ) defect due to strong field localization in the ENZ medium. The inherent weak magneto-optical activity is significantly enhanced in ENZ medium. In our configuration, the wavelength shift of transmission peaks along two opposite incident directions can be up to 100 times higher than that in the case that the defect layer is a normal bismuth iron garnet. Such results will provide a new degree to design novel magneto-optical devices with small size, and may open novel routes to exploit advanced materials for steering the electromagnetic waves in nano-scale structures.