Observation of the longitudinal field of a focused laser beam by second-harmonic generation

We demonstrate second-harmonic generation from a (110) ZnSe crystal for focused, axially symmetric polarized beams. Distinctive distributions in polarization and intensity accompanying transverse mode conversion to higher-order Hermite-Gaussian or Laguerre-Gaussian modes are observed. A longitudinal electric field generated by a radially polarized beam is verified by the variation in the intensity distribution. (c) 2008 Optical Society of America.