TY - JOUR
T1 - Modulational instability in linearly coupled asymmetric dual-core fibers
AU - Govindarajan, Arjunan
AU - Malomed, Boris A.
AU - Mahalingam, Arumugam
AU - Uthayakumar, Ambikapathy
N1 - Publisher Copyright:
© 2017 by the authors.
PY - 2017/6/22
Y1 - 2017/6/22
N2 - We investigate modulational instability (MI) in asymmetric dual-core nonlinear directional couplers incorporating the effects of the differences in effective mode areas and group velocity dispersions, as well as phase- and group-velocity mismatches. Using coupled-mode equations for this system, we identify MI conditions from the linearization with respect to small perturbations. First, we compare the MI spectra of the asymmetric system and its symmetric counterpart in the case of the anomalous group-velocity dispersion (GVD). In particular, it is demonstrated that the increase of the inter-core linear-coupling coefficient leads to a reduction of the MI gain spectrum in the asymmetric coupler. The analysis is extended for the asymmetric system in the normal-GVD regime, where the coupling induces and controls the MI, as well as for the system with opposite GVD signs in the two cores. Following the analytical consideration of the MI, numerical simulations are carried out to explore nonlinear development of the MI, revealing the generation of periodic chains of localized peaks with growing amplitudes, which may transform into arrays of solitons.
AB - We investigate modulational instability (MI) in asymmetric dual-core nonlinear directional couplers incorporating the effects of the differences in effective mode areas and group velocity dispersions, as well as phase- and group-velocity mismatches. Using coupled-mode equations for this system, we identify MI conditions from the linearization with respect to small perturbations. First, we compare the MI spectra of the asymmetric system and its symmetric counterpart in the case of the anomalous group-velocity dispersion (GVD). In particular, it is demonstrated that the increase of the inter-core linear-coupling coefficient leads to a reduction of the MI gain spectrum in the asymmetric coupler. The analysis is extended for the asymmetric system in the normal-GVD regime, where the coupling induces and controls the MI, as well as for the system with opposite GVD signs in the two cores. Following the analytical consideration of the MI, numerical simulations are carried out to explore nonlinear development of the MI, revealing the generation of periodic chains of localized peaks with growing amplitudes, which may transform into arrays of solitons.
KW - Asymmetric nonlinear fiber couplers
KW - Coupled nonlinear Schrödinger equations
KW - Linear stability approach
KW - Modulational instability
UR - http://www.scopus.com/inward/record.url?scp=85021673338&partnerID=8YFLogxK
U2 - 10.3390/app7070645
DO - 10.3390/app7070645
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AN - SCOPUS:85021673338
SN - 2076-3417
VL - 7
JO - Applied Sciences (Switzerland)
JF - Applied Sciences (Switzerland)
IS - 7
M1 - 645
ER -