Abstract

Based on Snell’s law, when electromagnetic waves are obliquely incident at an interface, reflected waves are in the opposite side of the incident waves with respect to the interface normal, which is called as normal reflection (or positive reflection). Here, we experimentally demonstrate negative reflection of electromagnetic waves that obliquely impinge on an anisotropic coding metasurface, in which the reflected and incident waves are in the same side of the surface normal. The anisotropic coding metasurface is composed of an array of ellipse-shaped coding particles, exhibiting powerful controls to electromagnetic waves with arbitrarily oblique incidence by adding compensation coding sequences to the original coding pattern. In addition to the negative reflections, the anisotropic coding metasurface also shows powerful abilities to convert the obliquely-incident spatial waves to surface waves with high efficiency. More importantly, two orthogonally polarized spatial waves are converted to two surface waves propagating in different directions, one of which is in the same side of the obliquely incident wave with respect to the surface normal, resulting in negative surface wave. Experimental results have good agreements to theoretical and numerical predictions for both negative reflections and negative surface waves.  

Highlights

  • The unprecedented ability of metamaterials to manipulate electromagnetic (EM) waves in desired manners has provided a new route for designing strange devices, which has attracted much interest from both the physics and engineering communities

  • The real-time manipulation of wavefronts can be achieved by loading active components to these digital elements with their digital states being externally controlled by a field-programmable gate array (FPGA), realizing digital and programmable metasurfaces[29,32]

  • Independent controls of spatial waves with out-of-plane reflection and negative reflection We demonstrate the bi-functional performance of an anisotropic coding metasurface in controlling the PWs under oblique incidence. doi:10.1038/lsa.2018.8

Read more

Summary

Introduction

The unprecedented ability of metamaterials to manipulate electromagnetic (EM) waves in desired manners has provided a new route for designing strange devices, which has attracted much interest from both the physics and engineering communities. Many exotic phenomena, such as negative refraction, subwavelength imaging and invisibility cloaking, have been experimentally demonstrated throughout the EM spectrum[1,2,3,4]. The arrays of subwavelength-spaced scatterers, distributed on an ultrathin metasurface with a certain phase gradient, provide an added gradient wave vector, and alter the direction of the refracted beam, as determined by the generalized Snell’s law[11,19,20].

Methods
Results
Conclusion

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.