| Popis: |
Polarization is one of the most important properties of light, which is also a typical dimension for light field manipulation. With specially designed meta-atoms and tailorable phase distribution, metasurfaces have been employed to achieve arbitrary polarization state in linear regime. Moreover, metasurface is also a platform for various nonlinear light generation, which can be used to realize an integrated polarized light source combined with its powerful capability of polarization manipulation. Here, we demonstrate a nonlinear plasmonic metasurface that is able to simultaneously realize nonlinear light generation and polarization manipulation. Split-ring resonators (SRRs) and complementary split-ring resonators (CSRRs) rotated by 90 degrees are selected to generate orthogonal polarizations of second harmonic (SH) components under the same linear polarized fundamental wave (FW), respectively. Phase difference and amplitude ratio between SH components can be tailored by adjusting the arm length of SRRs and CSRRs. By introducing spatial offset between adjacent basic supercells, we can achieve phase difference between two orthogonal components and thus realize polarization control of output SH emission and beam splitting at the same time. Two separated SH beams with orthogonal circular polarizations are achieved from a linearly polarized FW, and illuminated by circularly polarized FW, the same nonlinear plasmonic metasurface can generate linearly polarized SH, which can be viewed as a SH quarter-wave plate. Furthermore, arbitrary elliptical polarized SH can also be obtained from properly designed nonlinear metasurfaces. Our design provides a new approach for miniaturized light source for special polarization requirement, which may have potential applications in integrated optics. |
