Polarized Emission From InGaN Light-Emitting Diodes With Self-Assembled Nanosphere Coatings

– Q Zhang, KH Li, and HW Choi

(a) Schematic diagram of the measurement setup, where θ is the detection angle. The device surface plane (green shade) is perpendicular to the incident plane (yellow shade). Arrows labeled TM and TE indicate the directions of light polarization. (b) Cross-sectional schematic diagram of the GaN LED with nanosphere coating. (c) Cross section of the Brillouin zone indicating the L_g-K-L detection path.

IEEE Photonics Technology Letters, vol. 24, 18, pp. 1642-1645 (2012)

The polarization behavior of light emission from InGaN light-emitting diodes (LEDs) with nanosphere opal coatings has been studied. The close-packed nanosphere opal films are self-assembled with 220-nm polystyrene nanospheres onto the LEDs. The optical transmission properties of transverse electric and transverse magnetic polarized light have been measured as a function of detection angle; an integrated p/s ratio of 2.2 has been obtained at a detection angle of 70°. The polarization of light propagating through the opal film is strongly related to the photonic bandgap of the 3-D 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.

DOI: 10.1109/LPT.2012.2211586