Single-layer silicon metalens for broadband achromatic focusing and wide field of view.

Achieving simultaneous broadband achromatic focusing and a wide field of view remains a significant challenge for metalenses. In this work, we begin with a quadratic phase profile, enabling full field-of-view designs, and apply dispersion engineering to minimize variations of the focal length across wavelengths, thereby substantially reducing both longitudinal and transverse chromatic aberrations. This is accomplished using only the propagation phase in a single layer of waveguide-like rectangular meta-atoms, without relying on geometric phase contributions. The fabricated metalens experimentally demonstrates a field of view of [Formula: see text], along with a tenfold reduction in focal length variations with wavelength compared to a conventional quadratic metalens, achieving a measured relative shift as low as 1.3% across the 1.5 µm - 1.6 µm range (limited by our experimental setup). This improvement also results in a constant focusing efficiency in the considered wavelength range, where a reference quadratic metalens exhibits a nearly twofold reduction. These experimental results validate the effectiveness of our design strategy in simultaneously enhancing the operational bandwidth and field of view of metalenses. The demonstrated performance can directly benefit beam steering applications in the near-infrared wavelength range and provides a path toward achromatic, wide field-of-view metalenses in the visible range for imaging systems.