https://doi.org/10.1140/epjp/s13360-023-03960-z
Regular Article
Impact of higher-order nonlinear saturation effects on modulation instability in three-core oppositely directed coupler with two negative index material channels
1
Department of Physics, Vel Tech Rangarajan Dr. Sagunthala R and D Institute of Science and Technology, 600062, Chennai, India
2
Department of Physics, Pondicherry University, 605014, Puducherry, India
3
Fatima College, Department of Physics, 625001, Madurai, Tamil Nadu, India
Received:
5
November
2022
Accepted:
7
April
2023
Published online:
23
April
2023
In this paper, we intend to carry out a detail investigation on influence of higher-order effects on the modulation instability scenario in the three-core triangular (NIM-PIM-NIM) oppositely directed coupler. Upon arriving at the expression for instability gain employing linear stability analysis, particular attention is paid to reveal the impact of stimulated Raman effect and the self-frequency shift over the instability gain and the side band formation in both normal and anomalous instances. The study brings out a novel result that a regime of instability gain still exists in normal group-velocity dispersion even though the modulational frequency (
) is zero. However, the benefits in instability at = 0 are zero when the dispersion is anomalous. The self-frequency shift, stimulated Raman effect, and saturable nonlinearity exhibit novel effects of introducing new side lobes and merging the existing side bands paving technique to generate solitary wave/solitons or very brief pulses.
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