  III-Nitride light emitting diodes (LEDs) are the backbone of ubiquitous
lighting and display applications. Imparting directional emission is an
essential requirement for many LED implementations. Although optical packaging,
nano-patterning and surface roughening techniques can enhance LED extraction,
directing the emitted light requires bulky optical components. Optical
metasurfaces provide precise control over transmitted and reflected waveforms,
suggesting a new route for directing light emission. However, it is difficult
to adapt metasurface concepts for incoherent light emission, due to the lack of
a phase-locking incident wave. In this Letter, we demonstrate metasurface-based
design of InGaN/GaN quantum-well structures that generate narrow,
unidirectional transmission and emission lobes at arbitrary engineered angles.
We show that the directions and polarization of emission differ significantly
from transmission, in agreement with an analytical Local Density of Optical
States (LDOS) model. The results presented in this Letter open a new paradigm
for exploiting metasurface functionality in light emitting devices.
