Polarized emission from InGaN light-emitting diode with self-assembled opal coating

The polarization behaviors of light emission from InGaN light-emitting diodes (LEDs) with nanosphere opal coatings have been studied. The close-packed nanosphere opal films are self-assembled with 220 nm polystyrene nanospheres onto the LEDs. Optical transmission properties of the TE and TM polarized light have been measured as a function of detection angle; an integrated p/s ratio of 2.16 has been obtained at the detection angle of 70°. The polarization of light propagating through the opal film is strongly related to the photonic bandgap of the three-dimensional photonic crystal and is also dependent upon the angle of incidence. Theoretical calculations by the transfer matrix method are found to be consistent with the measured results.