Phase-matched second-harmonic generation in core-shell nanowire hyperbolic metamaterial

Abstract

Second-harmonic generation is well-known nonlinear frequency conversion technique, which can be applied in nonlinear optical characterization of materials and all-optical signal processing. This phenomenon requires phase-matching to maximize the conversion efficiency of generated second-harmonic field. But the phase-matching condition is difficult to achieve because of dispersion of naturally existing materials. To overcome this limitation, we propose an innovative phase-matching technique, which is called hyperbolic phase-matching, that can be possibly achieved by managing dispersion of a hyperbolic metamaterial. Here, the hyperbolic metamaterial is made of two-dimensional periodic arrays of core-shell nanowires, which have aluminium gallium arsenide as a core and gold as a shell, immersed in anodic aluminium oxide matrix. We have demonstrated phase-matched conditions for two different non-collinear second-harmonic interacting configurations in the metamaterial, which can be created by tuning incident angle of pump field to optimal values. Finally, conversion efficiencies of transmitted and reflected second-harmonic pulses as a function of incident angle and input pulse intensity were examined. The maximum conversion efficiencies are obtained at optimal incident angle and largest pumping intensity. © 2022 Elsevier GmbH