Linear and nonlinear optical characterization of aluminum nanoantennas.

We experimentally determine the order of multiphoton induced luminescence of aluminum nanoantennas fabricated on a nonconductive substrate using electron-beam lithography to be 2.11 (±0.10). Furthermore, we optically characterize these nanostructures via linear dark-field microscopy and nonlinear multiphoton laser excitation. We hereby observe different spectral response functions that can be seen as a splitting of peak positions when the antenna arm length is increased to Larm > 150 nm which has not yet been reported for aluminum nanostructures.