Recently, Prof. Shulin Sun (School of Information Science and Technology at Fudan University) and the co-authors have published an invited review paper with the title of “Electromagnetic meta-surfaces: physics and applications” in Advances in Optics and Photonics (Ref: Adv. Opt. Photon. 11 (2), 380-479 (2019), DOI: 10. 1364 / AOP. 11. 000380) in collaboration with Prof. Lei Zhou (Physics Department at Fudan University). This journal is one top review journal in the field of optics with an impact factor of 21.3 in 2017 and only more than 10 papers per year.

The reviewer highly appreciated our work with the following comment: “I would like to personally thank the authors for putting together this excellent review paper”. In this review paper of 100 pages, Prof. Sun et al not only reviewed the development of the meta-surfaces in past more than 10 years, but also introduced important achievements of many excellent research groups in the world-wide. The authors have also pointed out several possible important developing directions of this field in the future.

After reviewing the history of optics, we find that the conventional methods to control lights are still quite limited even if we have known and investigated lights for thousands of years. For example, we always utilize a bulky optical lens with carefully fabricated curved surface to focus the lights for a long time. However, these devices suffer from some limitations, e.g., huge size, heavy weight and limited functionalities, being un-favored for optical applications in the future. To overcome these challenges, meta-surfaces are proposed recently in order to realize our dream of manipulating lights freely, which can be widely applied in a broad fields of energy, information, and national defense, etc. Compared to conventional optical elements, meta-surfaces exhibit several advantages, including mini-size, light weight and easy fabrication and integration. These characteristics are highly desired in many applications. Now, meta-surfaces has become one important and hot field of modern optics and photonics.

In 2011 and 2012, the groups from Harvard University, Purdue University and Fudan University have proposed the new concept of meta-surfaces, i.e., a kind of two-dimensional metamaterials composed by artificial subwavelength microstructures arranged in specific order. In previous studies, people have proposed homogenous meta-surfaces for manipulating the amplitude, phase and polarization of the light. For instance, we can fabricate the carefully designed meta-surfaces to make an opaque object (e.g., a metal film) being transparent. People have also designed another class of meta-surfaces as perfect light absorbers, behaving like “an optical black hole”. Recently, it is found the microstructures’ arrangement order of meta-surfaces can play an important role in light manipulations. By carefully designing local optical responses of microstructures at different positions, we can achieve numerous novel optical phenomena. The group from Harvard University proposed to utilize the gradient meta-surfaces to manipulate the directions of refraction and reflection beams. And our group has proposed the gradient meta-surface as a bridge linking the propagating waves and surface waves. All these phenomena go beyond the classic Snell’s law, and can be described by the new generalized Snell's law.

Prof. Sun et al have contributed a series of outstanding works in the field of meta-surfaces, including high-efficiency conversion from PWs to SWs, spin-polarized light manipulations, etc. They have the following awards in recent years, including “Important achievements of optics in China (2012)”; “First prize of Shanghai Natural Science (2016)”, “Outstanding Paper in LSA (2018)”, etc.

In this important review paper, Prof. Shulin Sun (School of Information Science and Technology at Fudan University) is the first author. And Prof. Qiong He (Physics Department at Fudan University), Prof. Jiaming Hao (Shanghai Institute of Technical Physics, CAS) and Prof. Shiyi Xiao are the co-authors. Prof. Lei Zhou (Physics Department at Fudan University) is the corresponding author. This work is supported by National Key Research and Development Program of China, NSFC, Science and Technology Commission of Shanghai Municipality, Fudan-CIOMP Joint Fund, etc.   

Figure. Novel electromagnetic wave manipulations by metasurfaces.