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We propose all-dielectric metasurfaces that can be actively re-configured using the phase-change material Ge2Sb2Te5 (GST) alloy. With selectively controlled phase transitions on the composing GST elements, metasurfaces can be tailored to exhibit varied functionalities. Using phase-change GST rod as the basic building block, we have modelled metamolecules with tunable optical response when phase change occurs on select constituent GST rods. Tunable gradient metasurfaces can be realized with variable supercell period consisting of different patterns of the GST rods in their amorphous and crystalline states. Simulation results indicate a range of functions can be delivered, including multilevel signal modulating, near-field coupling of GST rods, and anomalous reflection angle controlling. This work opens up a new space in exploring active meta-devices with broader applications that cannot be achieved in their passive counterparts with permanent properties once fabricated.

A novel method based on femtosecond laser-induced forward transfer for high-throughput and efficient fabrication of periodic multilayer plasmonic metamaterials is demonstrated. With precisely controlling laser raster path applied on sputtered multilayer thin films, the laser-ablated materials can be transferred to another substrate leaving the fabricated multilayer structure on the original substrate. Subsequently, three-dimensional metamaterials can be made by multilayer structuring. Moreover, all the experimental results show that to create such multilayer split resonant rings (SRRs) with uniform profile, the laser fluence should be fine controlled under proper conditions. The optical property of fabricated multilayer SRR array is investigated by optical measurements and finite-difference time-domain simulations, showing various resonant modes in the middle-IR region. The calculated induced current distributions exhibit rich resonance properties of the structures as well. This work markedly extends the laser direct writing technique to a wide application in fabricating complicated metamaterials and plasmonic devices efficiently.