%0 Journal Article
%T Large optical nonlinearity enabled by coupled metallic quantum wells
%J -
%D 2019
%R https://doi.org/10.1038/s41377-019-0123-4
%X New materials that exhibit strong second-order optical nonlinearities at a desired operational frequency are of paramount importance for nonlinear optics. Giant second-order susceptibility ¦Ö(2) has been obtained in semiconductor quantum wells (QWs). Unfortunately, the limited confining potential in semiconductor QWs causes formidable challenges in scaling such a scheme to the visible/near-infrared (NIR) frequencies for more vital nonlinear-optic applications. Here, we introduce a metal/dielectric heterostructured platform, i.e., TiN/Al2O3 epitaxial multilayers, to overcome that limitation. This platform has an extremely high ¦Ö(2) of approximately 1500£¿pm/V at NIR frequencies. By combining the aforementioned heterostructure with the large electric field enhancement afforded by a nanostructured metasurface, the power efficiency of second harmonic generation (SHG) achieved 10£¿4 at an incident pulse intensity of 10£¿GW/cm2, which is an improvement of several orders of magnitude compared to that of previous demonstrations from nonlinear surfaces at similar frequencies. The proposed quantum-engineered heterostructures enable efficient wave mixing at visible/NIR frequencies into ultracompact nonlinear optical devices
%U https://www.nature.com/articles/s41377-019-0123-4