Аннотация
In this paper, we present a numerical investigation of all-optical logic
gates based on a Mach-Zehnder Interferometer (MZI) configuration of
micro structured fibers, also known as photonic crystal fibers (PCF)
under optical OOK (on-off keying). We determine several relevant
quantities to characterize the system performance, such as transmission
and extinction ratio as a function of the nonlinearity profile (beta)
added to one of the Mach-Zehnder Interferometer (MZI) arms. High-order
effects such as third order dispersion, intrapulse Raman scattering and
self-steepening were included in the generalized nonlinear Schrodinger
equation describing the pulse propagation. For this study, we used an
optical pulse with a shape of hyperbolic secant of 100 fs (femtosecond).
A pumped laser with three power values was simulated. With critical power Pc = 103.5 kW (P = Pc), below the critical power P = 90 kW (P < Pc) and above the critical power P = 110 kW (P > Pc). We added a
nonlinearity profile in one of the Mach-Zehnder Interferometer (MZI)
arms. Nonlinearity profiles were expressed in terms of the parameter
beta. We studied three different profiles: constant, increasing and
decreasing. Our results show that the proposed device can be used to
obtain all-optical OR and XOR logic gates as well as logic functions A
and A.(B) over bar. The OR logic gate was the one which achieved the
greatest FOMELG (Figure of Merit of Logic Gates) when using increasing profile with critical power (P-0 = 103.5 kW) for beta = 1.05 and FOMELG = 15.68 dB. The XOR logic gate presented the greatest FOMELG = 7.75 dB when using the decreasing profile with power below the critical (P-0 = 90 kW) for beta = 1.44. These results provide support for applications
in all optical networks. (C) 2017 Elsevier Ltd. All rights reserved.
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