# Phase and dispersion engineering of metalenses: broadband achromatic focusing and imaging in the visible

**Authors:** Wei Ting Chen, Alexander Y. Zhu, Vyshakh Sanjeev, Mohammadreza Khorasaninejad, Zhujun Shi, Eric Lee, Federico Capasso  
**arXiv:** [1711.09343](https://arxiv.org/abs/1711.09343)  
**Date:** 2017-11-26  
**Summary page:** https://www.summarizepaper.com/en/paper/1711.09343v1/

## Key points

- Metasurfaces are a promising technology revolutionizing optical elements
- They enhance performance across applications like telecommunications, computing, and wearable optics
- Crucial for metasurfaces to maintain functionality over a broad range of wavelengths
- Novel approach by Wei Ting Chen et al. independently manipulates phase and group delay properties
- Breakthrough led to development of broadband transmissive achromatic metalenses with tunable dispersion characteristics
- Capabilities showcased include diffraction-limited broadband focusing and achromatic imaging from 470 nm to 670 nm
- Focal length variation minimal at just a few percent across the broad 200 nm bandwidth
- Approach utilizes only a single-layer metasurface without requiring spatial multiplexing or cascading techniques

## Summary

Metasurfaces have emerged as a promising technology with the potential to revolutionize optical elements. By miniaturizing and enhancing their performance across various applications such as telecommunications, computing, and wearable optics, metasurfaces offer new possibilities for creating high-performance optical elements that can operate seamlessly across diverse wavelengths in the visible spectrum. However, for metasurfaces to be widely adopted, it is crucial for them to maintain functionality over a broad range of wavelengths. In a recent study by Wei Ting Chen et al., a novel approach was demonstrated to address this challenge. By carefully selecting nanostructures within the metasurface design, they were able to independently manipulate both phase and group delay properties. This breakthrough led to the development of broadband transmissive achromatic metalenses that exhibit tunable dispersion characteristics across the visible spectrum. The researchers showcased the capabilities of these metalenses by achieving diffraction-limited broadband focusing and achromatic imaging within a wavelength range from 470 nm to 670 nm. Remarkably, the focal length variation remained minimal at just a few percent across this broad 200 nm bandwidth. What sets this approach apart is its simplicity - utilizing only a single-layer metasurface with thickness on the scale of the wavelength without requiring spatial multiplexing or cascading techniques. Overall, this study represents a significant advancement in metasurface technology and offers new possibilities for creating compact and efficient optical systems with improved functionality for various practical applications in optics and photonics. hold promise as an innovative solution for , enabling , achieving , and operating seamlessly across diverse wavelengths in the .