Browsing by Author "Khaidarov, E."
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Item Open Access Control of LED emission with functional dielectric metasurfaces(Wiley, 2020) Khaidarov, E.; Liu, Z.; Paniagua-Domínguez, R.; Ha, S. T.; Valuckas, V.; Liang, X.; Akimov, Y.; Bai, P.; Png, C. E.; Demir, Hilmi Volkan; Kuznetsov, A. I.The improvement of light‐emitting diodes (LEDs) is one of the major goals of optoelectronics and photonics research. LED integration to complex photonic devices requires precise control of the wavefront of the emitted light. Metasurfaces are spatial arrangements of engineered scatters that may enable this light manipulation capability with unprecedented resolution. Most of these devices, however, are only able to function properly under irradiation of laser light with a large spatial coherence. LEDs, on the other hand, have angularly broad, Lambertian‐like emission patterns characterized by a low spatial coherence, which makes the integration of metasurface devices on LEDs challenging. A novel concept for metasurface integration on LED is proposed, using a cavity to increase the LED spatial coherence through an angular collimation. The experimental demonstration of the proposed concept is implemented on a GaP LED architecture including a hybrid metallic‐Bragg cavity. By integrating a silicon metasurface on top, two different functionalities of these compact devices are demonstrated: directional LED emission at a desired angle and LED emission of a vortex beam with an orbital angular momentum. The presented concept is general, being applicable to other incoherent light sources and enabling metasurfaces designed for plane waves to work with incoherent light emitters.Item Open Access High-efficiency and low-loss gallium nitride dielectric metasurfaces for nanophotonics at visible wavelengths(American Institute of Physics Inc., 2017) Emani, N. K.; Khaidarov, E.; Paniagua-Domínguez, R.; Fu, Y. H.; Valuckas, V.; Lu S.; Zhang X.; Tan S.T.; Demir, Hilmi Volkan; Kuznetsov, A. I.The dielectric nanophotonics research community is currently exploring transparent material platforms (e.g., TiO2, Si3N4, and GaP) to realize compact high efficiency optical devices at visible wavelengths. Efficient visible-light operation is key to integrating atomic quantum systems for future quantum computing. Gallium nitride (GaN), a III-V semiconductor which is highly transparent at visible wavelengths, is a promising material choice for active, nonlinear, and quantum nanophotonic applications. Here, we present the design and experimental realization of high efficiency beam deflecting and polarization beam splitting metasurfaces consisting of GaN nanostructures etched on the GaN epitaxial substrate itself. We demonstrate a polarization insensitive beam deflecting metasurface with 64% and 90% absolute and relative efficiencies. Further, a polarization beam splitter with an extinction ratio of 8.6/1 (6.2/1) and a transmission of 73% (67%) for p-polarization (s-polarization) is implemented to demonstrate the broad functionality that can be realized on this platform. The metasurfaces in our work exhibit a broadband response in the blue wavelength range of 430-470 nm. This nanophotonic platform of GaN shows the way to off- and on-chip nonlinear and quantum photonic devices working efficiently at blue emission wavelengths common to many atomic quantum emitters such as Ca+ and Sr+ ions.