Visible light metasurfaces based on gallium nitride high contrast gratings

• Visible light metasurfaces are proposed based on GaN high contrast gratings.
• Focusing lens with high transmissivity and large numerical aperture is demonstrated.
• Visible light metasurfaces with beam steering ability is achieved.
• These devices are promising for enhancing extraction efficiency of GaN-based LEDs.
• It provides a way to control the output light propagation and polarization of LEDs.

We propose visible-light metasurfaces (VLMs) capable of serving as lens and beam deflecting element based on gallium nitride (GaN) high contrast gratings (HCGs). By precisely manipulating the wavefront of the transmitted light, we theoretically demonstrate an HCG focusing lens with transmissivity of 86.3%, and a VLM with beam deflection angle of 6.09° and transmissivity as high as 91.4%. The proposed all-dielectric metasurfaces are promising for GaN-based visible light-emitting diodes (LEDs), which would be robust and versatile for controlling the output light propagation and polarization, as well as enhancing the extraction efficiency of the LEDs.