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Metalenses, featuring ultra-compactness and CMOS compatibility, are limited by the compromise between the diameter, numerical aperture, and working waveband. To address this problem, we propose and numerically demonstrate a centimeter-scale metasurface-refractive hybrid metalens working in the band of 440 - 700 nm. Revisiting the general Snell law, we present the phase profile of a chromatic aberration correction metasurface that can apply to a plano-convex refractive lens of an arbitrary surface type. Simulated by our semi-vector method, the designed achromatic hybrid metalens achieves 81% chromatic aberration suppression and polarization insensitivity. Broadband imaging results of the hybrid metalens are further provided, verifying the achromatism of the designed hybrid metalens. It can find applications in camera lenses and other optical systems that need compact, high-performance lenses., 10 pages, 5 figures

Zoom metalens doublet exhibits unprecedented advantages over the traditional zoom lens in many aspects, like ultra-compactness, CMOS compatibility, and miniaturization. However, most of them can only work in a narrow band due to chromatic aberration. Here, we numerically demonstrate a broadband achromatic zoom metalens doublet inspired by the Moir\'e lens principle. This design is achieved by globally optimizing the multi-wavelength phase profiles of the metalens doublet in the visible. The doublet can achieve achromatic continuous 1-10 zoom range at wavelengths of 440 nm, 540 nm, and 640 nm, featuring high focusing efficiency up to 86.5% and polarization insensitivity., Comment: 4 pages, 5 figures

The measurement of the polarizations and phase profiles of a light beam in one shot is of crucial importance for fundamental researches and daily life. Recently, optical metasurfaces, the ultrathin inhomogeneous interface made of planner nanostructure arrays, have become multi-functional and compact platforms for various emerging applications. Here, we propose and demonstrate an integrated, ultra-compact and miniaturized optical multi-parameter detector, based on efficient metalens arrays featuring the basic pixel composed of 2×2 polarization-dependent metalenses. This multifunctional detector determines not only the spatially variant polarizations through relative focusing intensities, but also the phase gradient profiles via submicron displacements of focal points. To demonstrate its performance, we experimentally measure the beams of 18 scalar polarizations and 7 tilted wavefronts with our system, showing average relative errors of as low as 3.89% for polarization detections and 3.72% for phase gradient detections. Our work can be applied to polarization imaging, optical element topography diagnosis, complex structure light detection, target recognition and health care.

By changing the relative rotation between two metasurfaces, an adjustable metasurface doublet with a zoom factor ranging from 1 to 18 can be realized and used as a zoom imaging system.

For the design of achromatic metalenses, one key challenge is to accurately realize the wavelength dependent phase profile. Because of the demand of tremendous simulations, traditional methods are laborious and time consuming. Here, a novel deep neural network (DNN) is proposed and applied to the achromatic metalens design, which turns complex design processes into regression tasks through fitting the target phase curves. During training, x − y projection pairs are put forward to solve the phase jump problem, and some additional phase curves are manually generated to optimize the DNN performance. To demonstrate the validity of our DNN, two achromatic metalenses in the near-infrared region are designed and simulated. Their average focal length shifts are 2.6% and 1.7%, while their average relative focusing efficiencies reach 59.18% and 77.88%.

Metasurface-based lenses (metalenses) offer specific conceptual advantages compared to ordinary refractive lenses. For example, it is possible to tune the focal length of a metalens doublet by varying the relative angle between the two metalenses while fixing their distance, leading to an extremely compact zoom lens. An improved polarization-insensitive design based on silicon-nanocylinders on silica substrates is presented. This design is realized and characterized experimentally at 1550 nm wavelength. By varying the relative angle between the metalenses in steps of 10 degrees, tuning of the doublet focal length is demonstrated from -54 mm to -+3 mm to +54 mm. This results in a zoom factor of an imaging system varying between 1 and 18. For positive focal lengths, the doublet focusing efficiency has a minimum of 34% and a maximum of 83%. Experiment and theory are in very good agreement.

Ultraviolet (UV) light is widely used in nanofabrication and biomedical fields. However, in order to shape the wavefront of the UV beam, UV light needs to travel a relatively long distance in optical media that usually have strong UV absorptions. Thus the traditional UV lens is inefficient, costly, and easily aging under the radiation. Hopefully, dielectric metalenses represent a promising alternative. We design and numerically study a polarization-insensitive and achromatic metalens at UV spectra from 234 to 274 nm. The metalens consists of 1519 AlN nanopillars and its focal length is about 4.7 μm, with a