title: Nonlinear parity-time-symmetric transition in finite-size optical couplers.
abstract: Parity-time-symmetric (PT-symmetric) optical waveguide couplers offer a great potential for future applications in integrated optics, such as ultracompact reconfigurable all-optical signal processing. Here, we predict a nonlinearly triggered transition from a full to a broken PT-symmetric regime in finite-size systems described by smooth permittivity profiles and, in particular, in a conventional discrete waveguide directional coupler configuration with a rectangular profile. For these systems, we show that this phase transition occurs in PT-symmetric couplers, regardless of the details of their geometry, therefore suggesting a practical route for experimental realization of such systems.
authors.forename: Wiktor
authors.initials: W
authors.lastname: Walasik
authors.forename: Chicheng
authors.initials: C
authors.lastname: Ma
authors.forename: Natalia M
authors.initials: NM
authors.lastname: Litchinitser