Multifunctional metasurfaces fusing multiple sets of plasmonic antennas within a single layer open a new class of functional optical elements with superior integratability. Even though laser printing of metallic nanostructures has provided a new paradigm for post-customizing metasurfaces in a cost-effective means, the intuitively isotropic thermoplasmonic shape transition adversely tampers with the optical responses of complex plasmonic nanostructures to multiplexed attributes of light, failing advanced multi-functionalities. Herein, we demonstrate full-visible multifunctional metasurfaces by in situ anisotropic laser printing of Al cross nanostructures using single femtosecond pulses. The shape transition and corresponding plasmonic resonances of the two orthogonal arms can be independently and exquisitely modulated in the full-visible range with ultralow cross-talk by controlled irradiations. This is achieved by exploiting polarization-controlled ultrafast thermoplasmonic heating of Al (one-order-of magnitude faster than Ag and Au) and subsequent curvature-driven surface atom migration. Thereby, Janus prints featuring structural color/phase-modulated holographic images can be accomplished with polarization-controlled switches. This newly-developed laser post-printing method can be easily generalized to multiple sets of plasmonic antennas at single pixel levels and thus opens a new strategy to customize complex plasmonic nanostructures for multi-functional flat optics with considerable miniaturization and up-scalability including waveplates, holographic encryption and multiplexed optical storage.

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Optical multiplexing is of great importance in information processing, and offers the opportunity to dramatically increase the capacity of information systems. For example, multiplexing among different physical dimensions of light is regarded as an efficient means to substantially increase the capacity of optical data storage (ODS). Alternatively, the capacity can also be increased by multilevel coding. In this paper, we report on the combination of multiplexing among multiple physical dimensions and multilevel coding simultaneously to dramatically boost the capacity of ODS. The physical mechanism relies on the excitation power dependent thermal reshaping of the ODS medium mediated by wavelength and polarization sensitive random hot spots in a volume of coupled disordered gold nanorods (GNRs). The resulting electric field intensity varies drastically inside the focus spot of a laser beam when different combinations of polarization and wavelength are used. Therefore, different hot spots can be selectively activated and encoded by controlling the power of the recording beam, facilitating the realization of the polychromatic and polarized multiplexing of multilevel coding in the disordered plasmonic structure. Our results might find applications in high capacity optical data storage, watermarking, etc.