Design and fabrication of polarized InGaN light-emitting diodes and THz polarizer based on subwavelength metallic nanogratings

Abstract

InGaN light emitting diodes are poised to replace conventional light sources for general illumination application due to their higher luminous efficiency and long lifetime. For other applications such as in imaging, liquid crystal backlighting and 3D display, polarized light sources would be highly desirable. In this work, we designed polarized InGaN LED by integrating sub-wavelength metallic nano-grating fabricated on the emitting surface. We studied the choice of metals, the period, the thickness and the duty cycle of the grating. We experimentally demonstrated a linearly polarized surface emitting InGaN/GaN LED on sapphire substrate. Our finding suggests an effective way to make polarized light emitting devices, without using special oriented substrate, complex design, fabrication and packing process. We also investigated the extension of this technology to THz range. The performances of these subwavelength gratings in THz ranges are characterized by THz-TDS and FTIR.