Planar immersion lens with metasurfaces

TL;DR

This paper introduces a novel planar metasurface-based immersion lens capable of focusing electromagnetic waves into small spots within dielectric materials, demonstrated with a flexible microwave lens for wireless energy transfer.

Contribution

It presents the first planar metasurface immersion lens design, enabling compact, flexible optical components for focusing and energy transfer applications.

Findings

Achieves sub-wavelength focusing in dielectric materials.

Demonstrates wireless energy transfer through biological tissue mimicking material.

Fabricates an ultrathin, flexible microwave lens.

Abstract

The solid immersion lens is a powerful optical tool that allows light entering material from air or vacuum to focus to a spot much smaller than the free-space wavelength. Conventionally, however, they rely on semispherical topographies and are non-planar and bulky, which limits their integration in many applications. Recently, there has been considerable interest in using planar structures, referred to as metasurfaces, to construct flat optical components for manipulating light in unusual ways. Here, we propose and demonstrate the concept of a planar immersion lens based on metasurfaces. The resulting planar device, when placed near an interface between air and dielectric material, can focus electromagnetic radiation incident from air to a spot in material smaller than the free-space wavelength. As an experimental demonstration, we fabricate an ultrathin and flexible microwave lens and further show that it achieves wireless energy transfer in material mimicking biological tissue.