On the problem of controlled virtual refractive index

A method for controlling the refractive index that is based on the backward rescattering of the scattered and amplified electromagnetic waves is propo sed and analysed. The resulting field is a sum of the initial (probe) wave and the rescattered wave. The effective wave number of the total wave can b e varied by varying the gain. This variation in the wave number can be trea ted as a variation in the refractive index, although the physical propertie s of the medium do not change. The effective refractive index for the total wave propagating in such a device was called the virtual refractive index.