Abstract

The optical second harmonic (SH) response of single-crystal cubic metals, Al and Cu, have been investigated theoretically and experimentally. Experimentally, we have observed SH generation from (111) and (100) surfaces in air using linearly polarized nanosecond pulses with wavelengths of 1.06, 0.68, and 0.63 µm. The SH generation efficiency was found to exhibit strong anisotropy as a crystal is rotated about its surface normal. These results together with the experimental results of Tom and Aumiller¹ on (111) Cu indicate that, whereas the free electron contribution dominates the linear optical properties, interband effects must dominate the nonlinear optical properties. We investigated this conjecture theoretically in the case of Al by calculating the SH susceptibility tensor from a simple pseudopotential model² for the band structure. The calculations indicate that the anisotropic part of the tensor is due to interband effects only and that the interband contribution to the tensor is as large as or larger than the conduction electron response at optical frequencies.

© 1987 Optical Society of America