Optical nanocavity enabling hyper resolution in 2D and 3D two photon direct writing lithography towards flat metalens

An increasing amount of research is being devoted to improve the spatial resolution in direct laser writing (DLW) tech- nique allowing the fabrication of complex 2D and 3D nanoscale devices. Among the various possibilities, we exploited uncom- mon features as extraordinary transmittance, zero re ectance, giant dephasing and epsilon-near-zero relative permittivity of a metal/ insulator/ metal/ insulator (MIMI) planar multilayer to upgrade a standard two-photon DLW process to hyper resolution. The improved resolution opens new opportunities in the fabri- cation of next-generation nanoscale devices such as metalenses, photonic circuits to name a few and in thermoplamonics. A high writing resolution is crucial for industrial applications in fields like anti-counterfeiting and at optics. Having reduced the voxel size by 89% in height and 50% in width, we fabricated full- dielectric broadband metalenses and in order to demonstrate the full capability of the achieved hyper resoution flat detailed bas-relief of Da Vinci’s ”Lady with an Ermine” has been realized.