Multi-elliptic rogue wave clusters of the nonlinear Schrödinger equation on different backgrounds

In this work, we analyze the multi-elliptic rogue wave clusters of the nonlinear Schrödinger equation (NLSE) in order to understand more thoroughly the origin and appearance of optical rogue waves in this system. Such structures are obtained on uniform backgrounds by using the Darboux transformation scheme for finding analytical solutions of the NLSE under various conditions. In particular, we solve the eigenvalue problem of the Lax pair of order n in which the first m evolution shifts are equal, nonzero, and eigenvalue dependent, while the imaginary parts of all eigenvalues tend to one. We show that an Akhmediev breather of order n- 2 m appears at the origin of the (x, t) plane and can be considered as the central rogue wave of the so-formed cluster. We show that the high-intensity narrow peak, with the characteristic intensity distribution in its vicinity, is enclosed by m ellipses consisting of the first-order Akhmediev breathers. The number of maxima on each ellipse is determined by its index and the solution order. Since rogue waves in nature usually appear on a wavy background, we utilize the modified Darboux transformation scheme to build such solutions on a Jacobi elliptic dnoidal background. We analyze the vertical semi-axis of all ellipses in a cluster as a function of an absolute evolution shift. We show that the cluster radial symmetry in the (x, t) plane is broken when the shift value is increased above a threshold. We apply the same analysis on the Hirota equation, to examine the influence of a real parameter and Hirota’s operator on the cluster appearance. The same analysis can be applied to the infinite hierarchy of extended NLSEs. The main outcomes of this paper are the new multi-rogue wave solutions of the nonlinear Schrödinger equation and its extended family on uniform and elliptic backgrounds.