Localizing and focusing second-harmonic emission with nonlinear metamaterials

Recent research on second-harmonic generation in left-handed materials has shown a light localization mechanism that originates from an all-angle phase-matching condition between counter-propagating electromagnetic modes at fundamental and double frequencies. This phenomenon opens the route for the design of second-harmonic lenses. In this paper, we recall the essential nonlinear properties needed to generate second harmonic images of linear objects. We show that this approach enable one to realize SH images of objects placed inside or outside the nonlinear lens. In the case of an external source, two distinct devices are proposed: a double lens configuration which enables to image objects between symmetric metamaterial slabs, and a single lens case characterized by an impedance mismatched interface. The versatility of these SH lenses opens new routes for the second harmonic imaging technics since they are able to produce SH images from linear objects.