Radiation losses in photonic crystal slab waveguide to enhance LEDs efficiency

Two-dimensional photonic crystal slabs with different hole shapes in which air holes etched in slabs as a key factor of losses, is analyzed. As far as higher efficiency in Light Emitting Diodes (LED) structure is concerned, the research undertook to analyze these losses by investigating the role of the etched-holes shape in cladding through modifying the refractive index of holes and as a result changing the effective refractive index of cladding, entire space. Then, validating such results, photonic crystal slab waveguide is simulated in three ways namely regular three dimension, two-dimension cylindrical and cylindroconical, which demonstrates a good agreement with experimental data. Finally, it is shown that interaction of the guided light improves extraction of both lower order modes as well as higher order modes, which enhance LED efficiency.