Department of Electrical EngineeringMetasurfaces develop various applications, such as nonlinear holography, nonlinear wave mixing, and novel nonlinear light sources. In nonlinear optics, nonlinear harmonic generation from nonlinear metasurface provide a new degree-of-freedom. Nonlinear metasurfaces have various interesting properties, such as the relaxed phase matching constraints, efficient frequency mixing, and nonlinear local phase control. There have been studied, but the development of a single nonlinear metasurface platform is still needed to develop practical applications. In this thesis, I experimentally demonstrate a novel class of a nonlinear polaritonic metasurface platform using nanoantenna structures with three- or four-fold rotational symmetry. Using the metasurface, spin-controlled giant 2nd and 3rd order nonlinear responses can be generated simultaneously or selectively on the same chip. Furthermore, under a circular polarized beam condition, nonlinear local phases can be simply tuned continuously by changing the rotation angle of the meta-atom based on the Pancharatnam-Berry phase. -Based on continuous local nonlinear phase control, nonlinear beam-steering that maintain spin-controlled giant nonlinear response for the second- and third-harmonic generations, was experimentally demonstrated via gradient nonlinear polaritonic metasurfaces. The nonlinear metasurface platform that proposed in this study can be used to develop future practical applications such as nonlinear holography, nonlinear communication and so on.clos
