Second harmonic generation from metallo-dielectric multilayer photonic band gap structures

TL;DR

This study explores second harmonic generation in Ag/Ta2O5 multilayer structures, demonstrating a significant enhancement in conversion efficiency due to multilayer effects, with experimental results aligning with theoretical models.

Contribution

It provides the first detailed experimental and theoretical analysis of SHG in metallo-dielectric multilayers, showing enhanced efficiency over single metal layers.

Findings

Conversion efficiency increased by at least 30 times in multilayers.

Maximum SHG signal shifts to lower angles in multilayers.

Experimental results agree with coupled Maxwell-Drude oscillator models.

Abstract

We experimentally and theoretically investigate the second order nonlinear optical response of metallo-dielectric multilayer structures composed of Ag and Ta2O5 layers, deposited by magnetron sputtering. Second harmonic generation measurements were performed in reflection mode as a function of incidence angle, using femtosecond pulses originating from a Ti:Sapphire laser system tuned at 800 nm. The dependence of the generated signal was investigated as a function of pump intensity and polarization state. Our experimental results show that the conversion efficiency from a periodic metallo-dielectric sample may be enhanced by at least a factor of 30 with respect to the conversion efficiency from a single metal layer, thanks in part to the increased number of active surfaces, pump field localization and penetration inside the metal layers. The conversion efficiency maximum shifts from 70 degrees for the single silver layer down to approximately 55 degrees for the stack. The experimental results are found to be in good agreement with calculations based on coupled Maxwell-Drude oscillators under the action of a nonlinear Lorentz force term.