Unbreakable PT symmetry of exact solitons in inhomogeneous nonlinear optical media

We demonstrate analytically and numerically the existence of exact solitons in the form of double kink and fractional transform, supported by a symmetric transversally modulated defocusing nonlinearity acting as a pseudopotential combined with an antisymmetric gain-loss profile. We explain here that the PT symmetry is never broken in the dynamical system under study, even in the absence of any symmetric modulation of linear refractive index, and the transversally modulated defocusing nonlinearity comes in the way as a requirement to establish the ensuing PT symmetry. (C) 2015 Optical Society of America