Nonlinear resonance effects on thin micro structured aluminum metal gratings by high power fs-laser pulses

We present measurements and numerical findings of resonance effects in aluminum metal gratings on fused silica substrates. The spectral characterization measurements of the gratings are done with white light in the wavelength range of 600nm up to 1600nm. Nonlinear effects have been studied with a fs-laser system at the resonance wavelength of the gratings. The metal layers of the gratings are 20nm to 40nm thick, the gratings period is 500nm or 1000nm and the narrow gaps between the metal stripes consist of about 8nm thick aluminum oxide stripes. These structures were produced with a special micro structuring process and coating technique. Numerical modeling shows that light can pass through these gratings for a characteristic resonance wavelength. For fs-pulses we found the transmission to decrease for increasing pulse energy.