Modification of the Raman spectrum in epsilon-near-zero media

Materials with low permittivity enhance various nonlinear optical effects including the non-elastic light scattering. However, spectroscopic signals in that condition still are not well studied. In this work we theoretically demonstrate the modification of a stimulated Raman spectrum in epsilon-near-zero (ENZ) medium. Using analytical solution of the nonlinear wave equation we simulate the transformation of the spectrum of the Stokes wave depending on permittivity of the medium. The wavenumber of the spectral Raman band decreases when approaching to low values of both the real and the imaginary part of permittivity and the line shape becomes dispersive. The physical explanation of this behavior is provided. These results can substantially influence on the interpretation of spectroscopic signals of ENZ materials.