Recently, metasurface, a class of artificial materials that transcends natural materials through the orderly design of subwavelength structures, has become a new platform to realize complex optical EPs.

A common way to implement scattering EP in the acoustic/microwave range is regulating the loss of the gradient metasurfaces by introducing a specific loss in a unit cell. However, direct extensions of in-plane loss in a gradient metasurface from non-visible waveband to visible light remain a formidable challenge, since the adjustable in-plane loss and corresponding manufacturing process in the visible are lacking.

Furthermore, the complex and rebellious interplay between in-plane lossy structure and lightwave restricts optical efficiency. Therefore, achieving high-efficiency EP at optical non-Hermitian metasurface is still a challenging task in photonics. Notably, two-dimensional scattering systems operating at EPs in the visible are unexplored.

In a paper published in Light: Science & Applications, a team of scientists, led by Professor Cheng-Wei Qiu from Department of Electrical and Computer Engineering, National University of Singapore, Singapore and Xinbin Cheng from Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai, and co-workers have reported a universal paradigm for achieving a high-efficiency EP in the visible by leveraging interlayer loss to accurately control the interplay between the lossy structure and scattering lightwaves.