On the nonreciprocal propagation of light waves in asymmetric lossy system of thin films

Optical nonreciprocity is the phenomenon where light behaves differently when traveling in the forward direction compared to the backward direction. This nonreciprocal behavior is typically achieved in systems that exhibit electromagnetic coupling, temporal variation, and nonlinear properties. In this work, we demonstrate that nonreciprocal behavior can also exist in an optically asymmetric lossy system without requiring these conditions. In our study, we theoretically investigate the nonreciprocal propagation of light waves in a passive asymmetric optical system made from a thin film that experiences some losses. Our theoretical analysis has been experimentally validated. This type of system can be utilized in passive nonreciprocal devices.