Off-axis bifocal metalens for displacement measurement.
Nanotechnology
; 35(21)2024 Mar 04.
Article
en En
| MEDLINE
| ID: mdl-38320325
ABSTRACT
Metasurface is a new type of micro-optical element developed in recent years. It can intelligently modulate electromagnetic waves by adjusting the geometrical parameters and arrangement of dielectric structures. In this paper, a bifocal metalens based on modulation of propagation phase was designed for the potential application in displacement measurement. The phase of the bifocal lens is designed by the optical holography-like method, which is verified by the scalar diffraction theory. We designed a square aperture lens with a side length of 200µm to realize two focal spots with focal lengths of 900 and 1100µm. The two focal spots aren't on one optical axis. The polarization insensitive TiO2cylinders are chosen as structure units. Four structures with different radius were selected to achieve the four phase steps. We fabricated the designed bifocal metalens using electron beam lithography and atomic layer deposition techniques, and measured the light intensity in the areas near the two foci in the direction of the longitudinal axis. The differential signal was calculated, from which we obtained a linear interval. It demonstrates the ability of bifocal differential measurement to be applied to displacement measurement. Because the metasurfaces production process is semiconductor compatible, the bifocal lens is easy to integrate and can be used for miniaturized displacement measurements, micro-resonators, acceleration measurements, and so on.
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1
Colección:
01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
Nanotechnology
Año:
2024
Tipo del documento:
Article
Pais de publicación:
Reino Unido