Propagation and excitation properties of nonlinear surface plasmon polaritons in a rectangular barrier

TL;DR

This paper investigates the nonlinear propagation, control, and interaction of surface plasmon polaritons in a three-level EIT system with a rectangular barrier, revealing mechanisms for transmission, trapping, reflection, and mode excitation.

Contribution

It introduces a theoretical framework for nonlinear SPPs in a barrier-modulated EIT system, including the derivation of a nonlinear Schrödinger equation and analysis of mode behaviors and an optical switch design.

Findings

Adjustable barrier controls SPP transmission, trapping, and reflection.

Periodic transverse modes can be excited within the barrier.

Proposed optical switch enables control of nonlinear SPPs.

Abstract

We propose a scheme to study the nonlinear propagation properties of nonlinear surface plasmon polaritons (SPPs) in a three level $\Lambda$ type electromagnetically induced transparency (EIT) system with modulation of a rectangular barrier. Based on the multi scale method, the nonlinear Schr\"odinger equation (NLSE) describing nonlinear propagation of SPPs is derived, and the rectangular barrier affecting propagation of nonlinear SPPs is provided by an off-resonance Stark field. For the single nonlinear SPPs incident case, by adjusting the height and half width of the barrier, we can realize transmission, trapping and reflection of the nonlinear SPPs. For two nonlinear SPPs symmetrical incident case, we find that a periodic intensity distribution in transverse direction mode can be excited in the rectangular barrier, and we study the relationship between propagation properties of such excited modes in the barrier with nonlinearity, half width of the barrier and phase difference of the initial nonlinear SPPs. In addition, we design an optical switch of nonlinear SPPs based on the above results. The results obtained here not only provide a theoretical basis for the study of the interaction between nonlinear SPPs and external potentials, but also have broad application prospects in the field of optical information at micro/nano scale.