Imaging Performance of Polarization-Insensitive Metalenses

Abstract

Metasurfaces have recently emerged as a promising technology to realize flat optical components with customized functionalities. In particular, their application to lenses in various imaging systems is of significant interest. However, a systematic and complete study of the focusing and imaging behavior of metalenses has not yet been conducted. In this work we analyze not only the on-axis focusing performance, but also the field-dependent wavefront aberrations via a phase-retrieval optimization method. We find that, particularly for high-NA metalenses, the field-dependent geometrical aberrations like coma are dominant at the design wavelength, while for longer and shorter operation wavelengths, the effective numerical aperture is decreased and mainly spherical aberrations are dominant. Additionally, we investigate the spectral and angular bandwidth of a polarization-insensitive metalens by analyzing the metalens efficiencies as a function of numerical aperture, field angle, and wavelength. We then compare the metalens performance to its refractive and diffractive counterparts and show how the respective metalens properties affect the imaging performance. For this purpose, we perform an imaging simulation for these three cases based on their field- and wavelength-dependent absolute deflection efficiencies and analyze the imaging properties of an extended test object. Our calculations show that metalenses can outperform diffractive lenses in terms of their angle-dependent efficiency for large deflection angles.

Metasurface-generated complex 3-dimensional optical fields for interference lithography

“…Optical metasurfaces are 2D arrangements of scatterers that are designed to modify different characteristics of light such as its wavefront, polarization, intensity distribution, or spectrum with subwavelength resolution (24–28). By proper design of the scatterers, different characteristics of the incident light can be engineered, and therefore different optical elements like gratings, lenses, holograms, waveplates, polarizers, and spectral filters can be realized (29–37). Furthermore, a single metasurface can provide novel functionalities, which, if at all possible, would require a combination of complex optical elements to implement (38–43).…”

Improving the light collection efficiency of silicon photomultipliers through the use of metalenses

“…We find an average angular transmission efficiency of (59 ± 1)% between 0°and 55°. It is worth mentioning that metalenses have better angular efficiency compared to conventional saw-tooth Fresnel lenses because the latter suffer from shadow effects [15].…”

Imaging based on metalenses

“…According to the generalized Snell's law deduced by the Fermat principle and the law of conservation of momentum, the reflected wave and the transmitted wave can be arbitrarily redirected only by designing the spatial phase response of the optical resonators forming the optical interface [47,48]. Some metalenses with significant characteristics are widely required in practical use [49]. Thus, in what follows, different efforts to control different-functionalities metalenses are made by numerous groups by utilizing different geometries and materials for different incident polarizations of EM wave.…”