Optical nonlinearities, combined with structural asymmetry, can break reciprocity and realize devices that transmit light asymmetrically. We show the first experimental implementation of this concept for free-space radiation, using silicon metasurfaces supporting asymmetric quasi-bound states.

Photonic Materials

Cotrufo, M., Cordaro, A., Polman, A., & Alù, A. (2022). Nonlinearity-Induced Nonreciprocity in Passive Silicon Gratings Supporting Quasi-Bound States in the Continuum. In Conference on Lasers and Electro-Optics, Technical Digest Series (Optica Publishing Group, 2022), paper FF4N.6. doi:10.1364/CLEO_QELS.2022.FF4N.6