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

TL;DR

This paper presents a novel single-layer silicon metalens design that achieves broadband achromatic focusing and a wide field of view by dispersion engineering, significantly reducing chromatic aberrations and improving focusing efficiency.

Contribution

The work introduces a dispersion-engineered, propagation-phase-only metalens design that simultaneously enhances bandwidth and field of view without relying on geometric phase.

Findings

Achieved 86° field of view in experiments.

Reduced focal length variation to 1.3% across 1.5-1.6 μm.

Doubled focusing efficiency compared to conventional designs.

Abstract

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 waveguide-like rectangular meta-atoms, without relying on geometric phase contributions. The fabricated singlet metalens experimentally demonstrates a field of view of 86{\textdegree}, 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 $\mu$m - 1.6 $\mu$m range (limited by our experimental setup). This improvement also leads to a twofold increase in focusing efficiency relative to the reference metalens. 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