According to one aspect of the present invention, a light emitting diode
(LED) structure including an active core layer and at least one substrate
layer having a first refractive index, comprises a 2-dimensional photonic
quasicrystal in the structure, the photonic quasicrystal comprising an
array of regions having a second refractive index, the array exhibiting
long range order but short range disorder. The long range order is
associated with diffractive properties of the structure and gives rise to
uniform-far field diffraction patterns from the LED. The present
invention enjoys the benefit of improved light extraction from LEDs
without undesirable far field illumination patterns.