title: All-optical PT-symmetric conversion of amplitude (phase) modulation to phase (amplitude) modulation.
abstract: We study electromagnetic field propagation through a planar three-waveguide coupler with linear gain or loss in a configuration that is the optical analog of a quantum PT-symmetric system. This model is experimentally feasible on at least four proven architectures: lossy waveguide couplers, pumped waveguides couplers, non-Hermitian electronics and coupled pumped whispering gallery mode resonators. We show that our device provides all-optical amplitude (phase) to phase (amplitude) conversion in the PT-symmetric regime at given propagation lenghts. The device has a π amplitude to phase conversion range if an extra binary phase is allowed in the reference signal, and a phase to amplitude conversion range that depends linearly on the gain-to-coupling ratio of the system. Our scheme may prove valuable in implementing phase shift keying formats, which have longer unrepeated transmission distance than intensity modulation schemes.
authors.forename: Oscar Ignacio Zaragoza
authors.initials: OI
authors.lastname: Gutiérrez
authors.forename: Luis Felipe Salinas
authors.initials: LF
authors.lastname: Mendoza
authors.forename: B M
authors.initials: BM
authors.lastname: Rodríguez-Lara