title: Numerical simulation of a dual frequency all-optical flip-flop based on a nonlinear semiconductor distributed feedback laser structure.
abstract: A new all-optical flip-flop generating light at two different wavelengths λ1 (state "a"), or λ2 (state "b") was suggested. It consists of an active layer and a nonlinear wave-guiding layer. Two parallel nonlinear gratings having different periods and periodic negative nonlinearities exist along the propagation direction in the wave-guiding layer. In state "a," the first grating provides the optical feedback for lasing, and the second grating is weak. In state "b," due to optical nonlinearity, the first grating weakens, and the second one provides the optical feedback for lasing. The refractive index nonlinearity is due to the direct absorption of photons at the Urbach tail. The device is triggered from state "a" to state "b" and vise versa by input optical pulses of wavelengths λ2 and λ1, respectively. The time domain simulations show switching dynamics in nanosecond time scale.
authors.affiliation: Advanced Technology and New Materials Research Institute, City of Scientific Research and Technology Applications, New Borg EL-arab City, Alexandria, Egypt. zoweil@gmail.com
authors.forename: Hossam
authors.initials: H
authors.lastname: Zoweil