Fig. 4: Fabrication process and SEM images of the fabricated multilayer metasurfaces.
From: Bilayer optical metasurfaces with multiple broken symmetries for nonlinear wavelength generation
a Flowchart of the developed nanofabrication process. The structures were fabricated through a multilayer process comprising PECVD deposition of amorphous silicon, electron-beam lithography with a chromium mask, reactive-ion etching, and a spin-on-glass spacer to embed and separate the two metasurface layers. b Tilted-view image showing the grating dimensions of a single layer. c Cross-sectional view of the multilayer structure with the in-plane displacement of 100 nm.
