Experimental study of surface-enhanced second-harmonic generation on silver gratings

Abstract

We performed an experiment of surface-enhanced second-harmonic generation on silver gratings of various groove depths. Using gratings with constant periodicity (1800 grooves/mm), we measured the intensity of the diffracted orders 0 and -1 at the second-harmonic frequency. This was done by varying the angle of incidence of the pump beam and also testing several different groove depths. We get an enhancement of the second-harmonic intensity by a factor of about 36 as compared to the flat silver case. Our data show that this enhancement, which arises from the surface-plasmon resonance at the pump frequency, depends strongly on the groove depth. In addition, we demonstrate an important and new result: There exists an optimum value of the groove depth for which this enhancement is maximum. A good agreement is found between our measurements and results predicted by the theory of diffraction in nonlinear optics [R. Reinisch and M. Neviere, Phys. Rev. B 28, 1870 (1983)].