Observation of asymmetric solitons in waveguide arrays with refractive index gradient

TL;DR

This paper reports the experimental discovery of asymmetric, stable solitons in waveguide arrays with a refractive index gradient, revealing new soliton families and complex propagation behaviors in nonlinear optical systems.

Contribution

It introduces the observation of asymmetric solitons induced by a refractive index gradient in waveguide arrays, a novel phenomenon in nonlinear optics.

Findings

Asymmetric solitons are stable during propagation.

Refractive index gradient causes new soliton families.

Experimental observation confirms theoretical predictions.

Abstract

We study light propagation in waveguide arrays made in Kerr nonlinear media with a transverse refractive index gradient, and we find that the presence of the refractive index gradient leads to the appearance of a number of new soliton families. The effective coupling between the solitons and the localized linear eigenmodes of the lattice induces a drastic asymmetry in the soliton shapes and the appearance of long tails at the soliton wings. Such unusual solitons are found to be completely stable under propagation, and we report their experimental observation in fs-laser written waveguide arrays with focusing Kerr nonlinearity.