Double-discrete solitons in fishnet arrays of optical fibers

TL;DR

This paper explores the unique propagation of light in fishnet arrays of optical fibers, revealing double-discrete solitons and self-collimation phenomena resulting from the array's discrete transverse and longitudinal structures.

Contribution

It introduces the concept of double-discrete linear and nonlinear light propagation in fishnet fiber arrays, including the formation of novel double-discrete solitons and their interactions.

Findings

Double-discrete self-collimation in linear regime

Formation of double-discrete spatial solitons with nonlinearities

Solitons bifurcate from different linear dispersion branches and form composite states

Abstract

We demonstrate that crossed arrays of optical fibers support the double-discrete linear and nonlinear propagation of light beams, in which not only the transverse coordinate (the fiber's number) is discrete, but also the longitudinal (propagation) coordinate, i.e., the number of the fiber-crossing site, is effectively discrete too. In the linear limit, this transmission regime features double-discrete self-collimation. The nonlinear fishnet arrays with both focusing and defocusing nonlinearities give rise to double-discrete spatial solitons. Solitons bifurcating from two different branches of the linear dispersion relation feature strong interactions and form composite states. In the continuum limit, the model of the nonlinear fishnet reduces to a system of coupled-mode equations similar to those describing Bragg gratings, but without the cross-phase-modulation terms.