Fig. 4: Sample fabrication and measurement setup.
From: Chiral orbital lasing in a twisted bilayer metasurface
a Fabrication processes for twisted bilayer metasurfaces, that include metal deposition and lift-off, e-beam lithography, inductively coupled plasma etching, alignment by marks, and lower-temperature bonding. b Scanning electron microscope (SEM) images of the fabricated sample that was cleaved by focused ion beam (FIB). The zoom-in image shows the sample consisting of the upper and lower metasurfaces overlaid at a twisted angle, with their structural parameters being measured and marked. The air holes are slightly damaged during the wet-etching process to remove the upper cladding for the observation. c Schematic of the confocal 4f measurement setup. BS beam splitter, M gold-coated mirror.
