Waveguides induced by grey screening solitons

We investigate the properties of waveguides induced by one-dimensional greyscreening solitons in biased photorefractive crystals. The results show thatwaveguides induced by grey screening solitons are always of single mode for allintensity ratios, i.e. the ratios between the peak intensity of thesoliton and the dark irradiance. Our analysis indicates that theenergy confined near the centre of the grey soliton and the propagation constant ofthe guided mode of the waveguide induced by the grey screening solitonincrease monotonically with intensity ratio increasing. On the other hand,when the soliton greyness increases, the energy confined near the centreof the grey soliton and the propagation constant of the guided mode of thewaveguide induced by the grey screening soliton decrease monotonically.Relevant examples are provided where photorefractive crystal is of thestrontium barium niobate type.