Stable optical vortices in nonlinear multicore fibers

Abstract

The multicore fiber (MCF) is a physical system of high practical importance. In addition to standard exploitation, MCFs may support discrete vortices that carry orbital angular momentum suitable for spatial-division multiplexing in high-capacity fiber-optic communication systems. These discrete vortices may also be attractive for high-power laser applications. We present the conditions of existence, stability, and coherent propagation of such optical vortices for two practical MCF designs. Through optimization, we found stable discrete vortices that were capable of transferring high coherent power through the MCF. Keywords: coherent energy propagation; multicore fibers; nonlinear vortices INTRODUCTION Vortex structures are widespread in nature and are found in both macroscopic atmospheric phenomena, such as tornadoes and the Great Red Spot of Jupiter, and microscopic-scale objects in quantum physics. Mathematically, vortices are related to topological defects, the accumulation of geometrical phases, and the phase singularity of a complex linear or nonlinear field (see, e.g., Refs. 1-8 and references therein).Optical vortices present a fascinating and expanding area of research that combines fundamental theoretical and mathematical science and maturing applied technologies (see recent review 4 ). Optical vortices are characterized by a wave field with zero intensity, an undefined phase in the vortex center (pivot point) and the presence of a screw dislocation of the wave front 5,6 . All transmutations of vortices in linear and nonlinear fields obey the conservation of the topological charge S, which is defined as the total change of the phase along a closed curve surrounding the pivotal point of the vortex divided by 2p. The special behavior of the phase and amplitude near the vortex pivot point results in the circular flow of energy in optical vortices [7][8][9][10] . This property is closely related to the ability of optical vortices to carry orbital angular momentum and energy [11][12][13][14] . This property is interesting for various applications, such as in optical traps [15][16][17] , information transmission 18-20 , astrophysics 21,22 , microscopy 23,24 , and laser micromachining 25,26 .In nonlinear media, optical vortices are treated as (topological) vortex solitons 4,27,28 . Such topologically stable pulses can act as information carriers 4,[29][30][31] . It is important that continuum vortex solitons are highly sensitive to azimuthal instability. Stabilization is possible by applying optically induced photonic lattices, which lead to a discrete optical vortex field. Different types of discrete lattice vortex solitons were theoretically predicted in the Refs. 32-35 and experimentally demonstrated in the Refs. 36,37. Discrete vortex solitons can also be created in photonic crystal fibers and other types of photonic lattices 38,39 . Discrete vortex solitons are frequently associated with soliton clusters, which feature interesting mobility properties and

The Effect of Spatial Mode Distribution on Coupling Efficiency of Single-Mode Fiber: Theoretical Analysis and Experimental Verification

“…Atmospheric laser transmission and detection (ALTD) technology, such as gas sensing lidar (GSL) and free space optical communication (FSOC), has become a very popular topic in the laser application technology field [1][2][3][4][5][6][7][8][9][10][11][12]. Optical fiber devices are becoming increasingly sophisticated as new optical fiber components (e.g., transmitter and receiver modules, erbium-doped fiber amplifiers (EDFAs), and multiplexer and demultiplexer units for wavelength division multiplexing) are established [13][14][15][16][17][18][19][20][21]. The ALTD system performance can be greatly improved by using optical fiber devices.…”

Discrete breathers for a discrete nonlinear Schrödinger ring coupled to a central site

“…This work has been extended to a model which also included gain and loss [17]. Recently there have also been studies of discrete vortices for the DNLS model [18]. Ref.…”

Localized modes in nonlinear binary kagome ribbons

“…Particular behavior of phase and amplitude of dynamically stable ring-vortex structures arises from circular flow of energy around a pivot point [41][42][43][44][45][46]. This property is closely connected with the ability of such structures to carry unchanged the orbital angular momentum and energy to long distances, which can be interesting for technological applications as spatial-division multiplexing (communication lines) and directional transfer of huge energy through the system (high-power lasers).…”

“…In addition to the ring structures of the staggered type, which are found to lose stability in the strongly nonlinear binary kagome ribbons, here we found conditions under which it is possible to obtain different types of dynamically stable vortex-ring solutions, the unstaggered ringlike solutions, hourglass solutions inside the semi-infinite gap, and minigap solitons inside the gaps opened due to lattice binarism. Vortex ring solutions, identified in different settings, studied here in the context of orbital momentum carriers, are also suitable for spatial-division multiplexing, actively studied in high-speed optical communications for increasing bandwidth [41][42][43][44][45][46]. Finally, Sec.…”