Changes in the spectrum of partially coherent flat-top light beam propagating in dispersive or gain media

Based on the flat-top beams model proposed by Li and the propagation theory of partially coherent light, the analytical expression for the spectrum of partially coherent flat-top beam propagating in dispersive or gain media is derived, and the spectral properties are studied quantitatively. The on-axis spectrums in near- and far-fields are analyzed. The effects of dispersive and gain properties of the media as well as the light source parameters such as central frequency, spectrum width and spatial coherence parameter on the spectral shift have been discussed in detail. Our results show that the refractive index of dispersive media and the light source parameters affect the spectral shift, and the profile of flat-top beam determines the spectral changes of blue-shift alternating with red-shift in near-field whereas blue-shift in far-field, which would be useful for the experiments.