Spin-Selective Second-Harmonic Vortex Beam Generation with Babinet-Inverted Plasmonic Metasurfaces

摘要

Metasurfaces have drawn considerable attentions for their revolutionaryrncapability of tailoring the amplitude, phase, and polarization of light.rnBy integrating the nonlinear optical processes into metasurfaces, newrnwavelengths are introduced as an extra degree of freedom for furtherrnadvancing the device performance. However, most of the existing nonlinearrnplasmonic metasurfaces are based on metallic nanoantennas as meta-atoms,rnsuffering from strong background transmission, low laser damage thresholdrnand small nonlinear conversion efficiency. Here, Babinet-inverted plasmonicrnmetasurfaces made of C-shaped nanoapertures as meta-atoms are designedrnand demonstrated to solve these issues. Rotation-gradient nonlinearrnmetasurfaces are further constructed for producing spin-selective secondharmonicrnvortex beams with the orbital angular momentum (OAM) and beamrndiffraction angle determined by both the spin states of the fundamental wavernand second-harmonic emission. The results enable new types of functionalrnmetasurface chips for applications in spin, OAM, and wavelength multiplexedrnoptical trapping, all-optical communication, and optical data storage.