Probe beam wave-guiding induced by spatial dark soliton in photorefractive Bi12TiO20 crystal

Abstract

Optical waveguides have produced a new wave of interest with realizing the fact that the light can be guided by light. These phenomena occur when an intense (pump) light beam propagates in an optically nonlinear medium, generating stable spatial structures called spatial soliton. Depending on the sign of non-linearity, spatial solitons can be bright or dark. The former one represents an isolate beam profile, and the latter one consists of the absence of radiation immersed in a continuous light background. Generation of dark spatial solitons can be performed by placing an amplitude or phase mask into the incident pump beam in order to produce the adequate initial condition. In particular, a 180° phase jump mask produces an odd number of dark solitons. Joined with the stability of such structures is the fact that the intensity of the beam modifies the medium itself, causing a change in the refractive index according to the intensity profile of the spatial solitons. Then another probe (weak) beam can be sent into the medium and can be guided along the soliton axes.