title: Non-reciprocal transmission and Schmitt trigger operation in strongly modulated asymmetric WBGs.
abstract: We investigate numerically a non-reciprocal switching behavior in strongly modulated waveguide Bragg gratings (WBGs) having a longitudinally asymmetric stopband configuration. The minimum power predicted for a stable switching operation is found to be approximately 77 mW for a realistic waveguide structure made of prospective materials; we assume in this paper a nano-strip InGaAsP/InP waveguide having longitudinally asymmetric modulation of the waveguide width. The analysis has been performed with our in-house nonlinear finite-difference time-domain (FDTD) code adapted to parallel computing. The numerical results clearly show low-threshold Schmitt trigger operation, as well as non-reciprocal transmission property where the switching threshold for one propagation direction is lower than that for the other direction. In addition, we discuss the modulation-like instability phenomena in such nonlinear periodic devices by employing both an instantaneous Kerr nonlinearity and a more involved saturable nonlinearity model.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Fujii
authors.forename: Ayan
authors.initials: A
authors.lastname: Maitra
authors.forename: Christopher
authors.initials: C
authors.lastname: Poulton
authors.forename: Juerg
authors.initials: J
authors.lastname: Leuthold
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Freude