Regularization of the spectral singularity in $\mathcal{P}\mathcal{T}$-symmetric systems by all order nonlinearities: Nonreciprocity and optical isolation

Xuele Liu, Subhasish Dutta Gupta, G. S. Agarwal

Spectral singularities are ubiquitous with PT-symmetry leading to infinite transmission and reflection coefficients. Such infinities imply the divergence of the fields in the mediu…