Radiative transfer computations for optical beams

In this paper, we present a method for computing direct numerical simulations of narrow optical beam waves propagating and scattering in a plane-parallel medium. For these computations, we use Fourier and Chebyshev spectral methods for three-dimensional radiative transfer that also includes polar and azimuthal angle dependences. We treat anisotropic scattering with peaked forward scattering by using a Clenshaw–Curtis quadrature rule for the polar angle and an extended trapezoid rule for the azimuthal angle. To verify our results, we compare this spectral method to Monte Carlo simulations.