In order to investigate the spatial distribution of electric field on illuminated metal strucutres, optical second harmonic (SH) intensity images of a silver grating has been observed. A stripe pattern was seen in the SH intensity image for the incident light polarization perpendicular to the lines of the grooves. We have found that the strongest SH radiation comes from the bottoms of the grooves of the grating. This result indicates that the enhancement of the incident electric field occurs at the bottoms of the grooves. The result is not consistent with available theoretical predictions.

© 2002 Optical Society of America

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