Unidirectional transmission is a fundamental function in signal processing. In electronic systems, simple semiconductor p–n diodes provide one-way transmission for electrical signals. In the optical domain, however, achieving one-way transmission is difficult because it requires breaking the time-reversal symmetry of light–matter interaction. Previously, magneto-optic effects have been successfully utilized to break the reciprocity of light–matter interaction. Here, we propose a meta-optic diode that supports nonreciprocal light transmission through excitation of asymmetric quasi-bound waves. The meta-optic diode consists of an ultrathin dielectric slab, patterned with two types of subwavelength resonator arrays. The proposed approach is based on the lifetime engineering of the resonant modes in the arrays and the inherent Kerr nonlinearity of the dielectric slab.
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