Abstract
The ability of metasurfaces to manipulate light at the subwavelength scale offers unprecedented functionalities for passive and active lasing devices. However, applications of metasurfaces to optical devices are rare due to fabrication difficulties. Here, we present quantum dot light emitting diodes (QDLEDs) with a metasurface-integrated metal electrode and demonstrate microscopically controlled LED emission. By incorporating slot-groove antennas into the metal electrode, we show that LED emission from randomly polarized QD sources can be polarized and directed at will. Utilizing the relation between polarization and emission direction, we also demonstrate microscopic LED beam splitting through the selective choice of polarization.
Highlights
Planar arrays of subwavelength structures, termed metasurfaces, have been attracting interest for controlling electromagnetic waves within a subwavelength-thickness interface[1,2,3,4,5,6]
The light emitting diodes (LEDs) has a bottom p-contact electrode made of indium tin oxide (ITO) and a top n-contact metal electrode
A quantum dots (QDs) LED uses Al metal alone for the top electrode because of its low work function of about 4.24 eV compared to 4.5 eV of the ITO used for the bottom electrode[24,25,26]
Summary
Planar arrays of subwavelength structures, termed metasurfaces, have been attracting interest for controlling electromagnetic waves within a subwavelength-thickness interface[1,2,3,4,5,6]. Integration of metasurfaces with active devices has been used to control the emission and nonlinear response of quantum cascade lasers in the mid-infrared or THz regime[12,13,14,15]. Metasurface-integrated active optical devices are rare because the small size of optical scatterers causes fabrication difficulties and low coupling efficiency with light emitters such as quantum wells (QWs), quantum dots (QDs), and molecule dyes. We show that the metasurface-integrated electrode actuates the LED, and steers the emission from randomly polarized sources into a linearly polarized and directed beam through polarization filtered by slot-antenna. LEDs with slot-groove-array structure of 400 nm spacing show the emission efficiency of about 4.5% compared to the electrode-free open space emission. We introduced pixelated slot-groove arrays where each pixel controls the beam separately and demonstrated polarization-dependent beamsplitting through the selective choice of polarization by a detecting polarizer
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