Article,
Logic gates based in two- and three-modes nonlinear optical fiber couplers
OPTICAL AND QUANTUM ELECTRONICS, 39 (14): 1191-1206 (2007)
DOI: 10.1007/s11082-008-9186-9
Abstract
In this paper we did a study of logic gates obtained in the operation of
a three-core non linear directional coupler (TNLDC) and an asymmetric
two-core coupler (DNLDC) operating in the CW regime (the laser signals
have the same wavelength). The symmetric three-core coupler (TNLDC),
with their cores identical, in a planar arrangement, was studied using a
control pulse applied to the first core. The second structure is an
asymmetric two-core coupler (DNLDC). Looking at the transmission
characteristics of the device, through the direct and cross channel, we
did a study of the extinction ratio (Xratio) of these devices. For both
devices we did a numerical investigation with the objective to implement
logic gates. The DNLDC supplied AND, OR and XOR gates while the TNLDC
supplied AND, NAND, OR, XOR and NOT gates. In comparing the performance
of both switches operating as logic gates (DNLDC and TNLDC) we define,
for the first time, a figure-of-merit of the logic gates (FOMELG). In
this criteria the FOMELG is defined as a function of the extinction
ratio of the gate outputs. Comparing the same gates of the three and
two-core NLDC we observe that the logical gates of the three-core TNLDC
present a better performance than the one of the two-core DNLDC
considering the figure of merit FOMELG, besides the fact that is simpler
to fabricate a symmetrical coupler (with identical cores) comparing with
an asymmetric coupler. We believe that the use of this figure of merit
will be useful in the study of the performance of logic gates to be used
in communication systems.
