Stable nonlinear amplification of solitons without gain saturation

O. V. Borovkova¹, V. E. Lobanov¹ and B. A. Malomed^1,2a

¹ ICFO-Institut de Ciencies Fotoniques, and Universitat Politecnica de Catalunya - Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain, EU
² Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University - Tel Aviv 69978, Israel

^a malomed@post.tau.ac.il

Received: 19 November 2011
Accepted: 9 January 2012

Abstract

We demonstrate that the cubic gain applied in a localized region, which is embedded into a bulk waveguide with the cubic-quintic nonlinearity and uniform linear losses, supports stable spatial solitons in the absence of the quintic dissipation. The system, featuring the bistability between the solitons and the zero state (which are separated by a family of unstable solitons), may be used as a nonlinear amplifier for optical and plasmonic solitons, which, on the contrary to previously known settings, does not require gain saturation. The results are obtained in an analytical form and corroborated by the numerical analysis.