Effect of photonic crystals on the light extraction of GaN-based LED for different polarization modes of spontaneous radiation

摘要

The light extraction efficiency (LEE) of different polarization modes have been simulated by FDTD solutions for three photonic crystal (PhC) structures, which are spherical-PhC LED, cylindrical-PhC LED and compound-PhC LED. The TE-and TM-mode LEE are simulated seperately. It shows that the discontinuity of the structure from the propagation direction will cause decrease of TE-mode and TM-mode LEE. TE and TM mode are enhanced by 60% and 40% in cylindrical-PhC LED, in which the single nanorod act as light waveguide. Finally, a multi-layer-compound-PhC-LED is proposed. Results show that the TM-mode LEE based on this structure is increased by 1.45 times at a wavelength of 532?nm, and the TM-mode illuminous intensity will be larger than that of TE mode, and then polarization inversion occurs.