We proposed and demonstrated an integrated high linearly polarized InGaN/GaN green LED grown on (0001) oriented sapphire with a structure of combined dielectric/metal wire grids (CDMWG). Both theoretical and experimental results show that the CDMWG can effectively loosen the requirement on the dimension of the grating, and the introduction of a low-refractive dielectric layer can further enhance both TMT and ER significantly for the GaN-type LED. An InGaN/ GaN green LED with an integrated CDMWG of 220 nm period has been fabricated, and a measured extinction ratio(ER) of higher than 20 dB and TMT of 65% within an angle of ±40° is obtained directly from a InGaN/GaN LED.
We propose and present a planar plasmonic lens formed by an array of spatially varying sub-wavelength rectangular annular patterned in the upper Au film of a metal-insulator-metal (MIM) structure. It is found that the reflected phase and amplitude can be well controlled by manipulating the width of the annular gaps and the length of the MIM cavity, in which localized surface plasmonic resonances occur. A reflective planar plasmonic lens that can generate a spherical wave-front in the reflected field has been realized through an optimized design at wavelength 1.55μm. Numerical results using the Finite Difference Time Domain (FDTD) method show that the focal length can be precisely controlled with a beam spot size at focal plane being close to the diffraction limits, and the focusing efficiency is up to 50%. It provides a great potential for applications in advanced nanophotonic devices and integrated photonic systems.