Propagation of nonparaxial vector Gaussian beam

Based on the nonparaxial vectorial moment theory of light beam propagation, the propagation characteristics of nonparaxial vector Gaussian beam have been system ically investigated. The results reveal that both the second_order_moment transv ersal beam widths follow a simple hyperbolic law for propagation. The analytical expression of the beam propagation factor is presented. The concise formulae ha ve been further given for highly nonparaxial case. And the maximum transverse di vergences are 90° as the dimension of light source tends to zero. When extendin g to the paraxial case, the obtained results are slightly different from the for merly paraxial formulae. Moreover, the beam propagation factor will always be gr eater than unity. Finally, comparison between the propagation of nonparaxial vec tor Gaussian beam and that of nonparaxial scalar Gaussian beam indicates that th e divergence angles show prodigious discrepancy for Gaussian light source within two times of wavelength scales.