Engineering Circular Dichroism in the Nonlinear Optical Region with a Refractory Plasmonic Molybdenum Metasurface

Chiral plasmonic metasurfaces exhibit circular dichroism (CD) and serve as a key tool for chiroptics. However, in the linear optical regime, the CD value remains fixed. Moreover, conventional chiral plasmonic metasurfaces suffer from poor photothermal stability, making it difficult to excite their nonlinear optical properties. Here, we present a refractory plasmonic molybdenum (Mo) metasurface that not only maintains strong chiroptical effects under extreme conditions, withstanding temperatures up to 1100 °C and laser intensities exceeding 12 GW/cm², but also realizes intensity-dependent tunable CD in the nonlinear optical region due to chiral saturated absorption and chiral reverse saturable absorption. In addition, our metasurface exhibits giant third-harmonic generation. Finally, we demonstrate a proof-of-concept circularly polarized light limiter based on this refractory chiral Mo metasurface.