Asymptotic behavior of spatial coherence of radiation field in statistically irregular waveguides

Abstract

We develop an asymptotic method for the calculation of spatial correlation function of the radiation field in statistically irregular open waveguides with an arbitrary profile of the refractive index in the transverse cross section. It is shown that the spatial correlation function of the field at large distances from the region of entry of the radiation into the waveguide is determined only by the distribution of the average power over the modes. In the case of multimode waveguide, this function can be determined by solving an equation of the Einstein~Fokker type for the density distribution of the rays. In the case of planar waveguides, this function is determined by expanding asymptotically the correlation function of the field with respect to a small quasiclassicity parameter. We consider a concrete example of open waveguide with random curvatures of the axis.