“…[25]. Further, optics provides a fertile ground to investigate PT -symmetric beam dynamics in nonlinear regimes, including the formation of bright and dark solitons, gap solitons, defect states, multi-peak modes, and vortices, see original works [26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48] and recent reviews [49,50]. In particular, a specific arrangement of the self-defocusing nonlinearity, growing from the center to periphery, makes it possible to predict self-trapped modes featuring unbreakable PT symmetry [51].…”