Nonreciprocal propagation in a non-Hermitian silicon photonic coupler employing graphene saturable absorptionDimitrios Chatzidimitriou, Alexandros Pitilakis, Traianos Yioultsis and Emmanouil KriezisEPJ Web Conf., 238 (2020) 11006DOI: https://doi.org/10.1051/epjconf/202023811006