Abstract
All-optical logic gates can enable many advanced functions such as
all-optical bit-pattern recognition, all-optical bit-error rate
monitoring, all-optical packet address and payload separation,
all-optical label swapping and all-optical packet drop in optical time
domain multiplexing (OTDM) networks. Recently, much attention has been
given to the influence of the relaxation process (sometimes called the
Debye relaxation model) of the nonlinear response because the usual
assumption of instantaneous nonlinear response fails for ultrashort
pulses and additional contributions coming from nonlinear dispersion and
relaxed nonlinearity have to be taken into account. The Kerr-Debye model
is a relaxation of the nonlinear Kerr model in which the relaxation
coefficient is a finite response time of the nonlinear material. In this
paper, we have presented a numerical analysis of the triangular fiber
coupler (TFC) for generation of the all-optical logic gates with
nonlinear optical (NLO) properties, where we consider the nonlinear
effects Kerr group velocity dispersion (GVD) and self-phase modulation
(SPM) instantaneous and relaxed (Kerr-Debye model). To implement
all-optical logic gates we used TFC of three symmetric configurations
Instantaneous (III), Relaxed (RRR-5 and RRR-9). In the instantaneous
condition, the TFC is made up of silica optical fibers (with
instantaneous response time - indicated by III) and in the relaxed
conditions (RRR-5 and RRR-9) the TFC is made up of fibers with delayed
response time of around 25 ps (for example, the polymer optical fibers).
In our paper, we are interested in the transmission characteristics, the
XRatio level (XR (dB)) as a function of the Delta Phi parameter, the
normalized time duration (NTD) and the pulse evolution along the TFC and
finally to compare the performance of all-optical logic gates, we will
use the figure-of-merit of the logic gates (FOMELG (dB)) defined as a
function of the extinction ratio of the gate outputs. All results were
obtained numerically, considering a very simple model for generation of
a optical logic gates.
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