Nonlinear light control in optical couplers: Harnessing PPTT-symmetry for enhanced beam propagation.

This study explored the evolution of nonlinear eigenmodes in coupled optical systems supported by PT-symmetric Rosen-Morse complex potential, in which one channel is with gain and the other is with loss. We assessed that the threshold potential above which PT-symmetry breakdown occurs is enhanced by coupling constant, by examining low- and high-frequency eigenmodes of ground and first excited states. The stability of eigenmodes was verified by stability analysis using Bogoliubov-de-Gennes (BdG) equations and it was established that even though the Rosen-Morse potential-supported system can create eigenmodes, it cannot support stable soliton solutions for any potential values.