Plasmonic enhancement of photoacoustic strain-waves on gold gratings

In this paper, we report on the time-dependent strain-wave-induced changes in reflection and diffraction of a gold plasmonic grating. We demonstrate efficient excitation strain waves using enhanced absorption at around surface plasmon polariton resonance. addition, observe that grating show an approximately quadratic dependence pump fluence when probed wavelength 400 nm. tentatively attribute non-linear behavior to strain-induced nonlinear interband transition energy. Using model calculates permittivity taking into account d s/p transition, deduce energy would have change by about 0.013 eV for measured reflection.