Abstract
Asymmetric dual core nonlinear directional couplers that include an
increasing self phase modulation profile are examined. The asymmetry is
associated with the self phase modulation profile of one of the channels
(direct channel). Looking at the transmission characteristics of the
device, through the direct channel, one observes that, when pumping in
the direct channel, there is a decrease in the critical power which is
lower compared with the symmetric coupler, and the critical power is a
single-value function of the nonlinearity. For the pump power in the
cross channel the transmission function of the coupler presents regions
of multistability, where the coupler presents more than one critical
power for certain values of the self phase modulation profile index. It
was also observed that all the profiles under study, with increasing
self phase modulation profile, present this behavior. For the studied
profiles, one region of multistability was observed where three possible
critical powers were observed. However, for the exponential profile, a
second region was observed for a higher value of the self phase
modulation profile parameter. It is concluded that to operate the
asymmetric coupler in a single-value region for the critical power, the
exponential self phase modulation profile presents the best behavior for
the profiles under study. (C) 2000 Elsevier Science B.V. All rights
reserved.
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