Direction control of colloidal quantum dot emission using dielectric metasurfaces

Abstract: Metasurfaces are expending their applications from the thickness shrinkage of passive optical elements such as lens, polarizer, and quarter-wave plate etc. to the integration with the active optical devices like vertical cavity surface emitting diodes due to the recent development of dielectric metasurfaces. Even though successful demonstration of directional lasing and beam shaping of laser emission, the integration of metasurfaces with random light sources such as light emitting diodes is limited in function and efficiency because metasurfaces are basically based on the resonance property of the nanostructure. In order to control the direction of emission from colloidal quantum dots, we present a dielectric metasurface deflector composed of two TiO2 nanoposts whose design was adapted from the optical Yagi-Uda nanoantenna. TiO2 deflector arrays were fabricated by a dry etching method and integrated with a colloidal quantum dot resonant cavity formed by sandwiching two distributed Bragg reflectors. To make it sure of the deflection ability of the fabricated sample, we measured the photoluminescence and far-field patterns of emission from the resonant cavity. From the obtained results, we could demonstrate that the colloidal quantum dot emission transmitted through our deflector arrays was deflected by 20° and the efficiency of deflecting was 71％ with respect to the emission from resonant cavity.