M2-factor of a truncated electromagnetic Gaussian Schell-model beam

Based on the extended Huygens–Fresnel integral and the second-order moments of the Wigner distribution function, analytical expression for the M2-factor of a truncated electromagnetic Gaussian Schell-model (EGSM) beam in turbulent atmosphere is derived by expanding the hard-aperture function into a finite sum of complex Gaussian functions. It is found that the evolution properties of the normalized M2-factor of a truncated EGSM beam are closely determined by the truncation parameter, the parameters of the source beam and the parameters of the turbulent atmosphere together. The advantage of the EGSM beam for overcoming the turbulence-induced degradation disappears gradually as the truncation parameter decreases.