title: Parity-time anti-symmetric parametric amplifier.
abstract: We describe the process of parametric amplification in a directional coupler of quadratically nonlinear and lossy waveguides, which belongs to a class of optical systems with spatial parity-time (PT) symmetry in the linear regime. We identify a distinct spectral PT anti-symmetry associated with optical parametric interaction, and show that pump-controlled symmetry breaking can facilitate spectrally selective mode amplification in analogy with PT lasers. We also establish a connection between the breaking of spectral and spatial mode symmetries, revealing the potential to implement unconventional regimes of spatial light switching through ultrafast control of PT breaking by pump pulses.
authors.forename: Diana A
authors.initials: DA
authors.lastname: Antonosyan
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Solntsev
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Sukhorukov