Spectral switches of partially coherent nonparaxial beams diffracted at an aperture

Based on the generalized Rayleigh diffraction integral, the spectral shifts and spectral switches of nonparaxial partially coherent beams diffracted at an aperture are Studied. Our main attention is paid to the effect of beam nonparaxiality on the spectral switches of partially coherent beams. It is shown that the spatial coherent parameter beta, trunction parameter delta and waist width-to-central wavelength ratio w(0)/lambda(0) affect the behavior of spectral switches. Only when beta, delta and w(0)/lambda(0) satisfy certain conditions, can the difference between the nonparaxial and paraxial results be negligible. The discrepancy arises physically from the change of the spectral modifier by using the paraxial approximation. (C) 2008 Elsevier B.V. All rights reserved.