Effect of a local nonlinearity on the light dynamics around an exceptional point: A quantitative analysis

Time-asymmetric state evolution due to the dynamical encirclement around a second-order exceptional point has garnered enormous attention for the topological study of various photonic structures. The selective mode-conversion in an optical waveguide can help in the designing of various integrated photonics devices. Here we explore a dual-mode planar optical waveguide and study the beam dynamics with the onset and offset of Kerr nonlinearity together with the encirclement of the identified exceptional point in the parameter space. The onset of the same amount of focusing and defocusing type nonlinearity in the waveguide gives two different outputs for a unidirectional propagation of light, beyond the chiral aspect of the device.