Browsing by Subject "Nanophotonics"

Now showing 1 - 15 of 15

Open Access
Active Nanophotonics
(IEEE, 2020) Alu, A.; Demir, Hilmi Volkan; Jagadish, c
Being able to manipulate and control light flows at small scales holds the promise to open groundbreaking opportunities for a variety of technologies. Consider, for instance, the challenges currently faced in the world of computing: as data rates and processing demands increase worldwide at an exponential rate, we are facing unsustainable increases in energy consumption associated with data centers and streaming providers. To address these challenges, optical computing and communications offer an interesting alternative to electronic-based systems. Using light for these purposes, however, is hindered by the fact that photons are not easily squeezed to volumes beyond the diffraction limit, i.e., below the wavelength scale, which would be required both to enable lowenergy computation at sufficiently high speeds and to match the degree of integration density available in electronic systems. Today, the field of optoelectronics, which combines highdensity electronic devices to process the data and low-energy data transport enabled by light, is growing at a very fast pace.
Open Access
Artificial olfaction inside nanostructured infrared fiber arrays
(IEEE, 2011) Yaman, Mecit; Yıldırım, Adem; Bayındır, Mehmet
Nanostructured hollow core fibers are used to demonstrate a new infrared absorption based artificial nose. The sensor unit of the array is a hollow core Bragg fiber that selectively guides incident blackbody radiation and enhances absorption for enhanced sensitivity. © 2011 IEEE.
Open Access
Colloidal nanophotonics: The emerging technology platform
(OSA - The Optical Society, 2016) Gaponenko S.; Demir, Hilmi Volkan; Seassal C.; Woggon U.
Dating back to decades or even centuries ago, colloidal nanophotonics during the last ten years rapidly extends towards light emitting devices, lasers, sensors and photonic circuitry to manifest itself as an emerging technology platform rather than an entirely academic research field. ©2016 Optical Society of America.
Open Access
Enhanced optical characteristics of light emitting diodes by surface plasmon of Ag nanostructures
(SPIE, 2011) Jang L.-W.; Ju J.-W.; Jeon J.-W.; Jeon, D.-W.; Choi J.-H.; Lee, S.-J.; Jeon, S.-R.; Baek J.-H.; Sarı, Emre; Demir, Hilmi Volkan; Yoon H.-D.; Hwang, S.-M.; Lee I.-H.
We investigated the surface plasmon coupling behavior in InGaN/GaN multiple quantum wells at 460 nm by employing Ag nanostructures on the top of a roughened p-type GaN. After the growth of a blue light emitting diode structure, the p-GaN layer was roughened by inductive coupled plasma etching and the Ag nanostructures were formed on it. This structure showed a drastic enhancement in photoluminescence and electroluminescence intensity and the degree of enhancement was found to depend on the morphology of Ag nanostructures. From the time-resolved photoluminescence measurement a faster decay rate for the Ag-coated structure was observed. The calculated Purcell enhancement factor indicated that the improved luminescence intensity was attributed to the energy transfer from electron-hole pair recombination in the quantum well to electron vibrations of surface plasmon at the Ag-coated surface of the roughened p-GaN. © 2011 SPIE.
Open Access
Enhanced transmission of electromagnetic waves through split-ring resonator-shaped apertures
(Society of Photo-Optical Instrumentation Engineers (SPIE), 2011-06-21) Sahin, L.; Aydin, K.; Sayan, G. T.; Özbay, Ekmel
The design of aperture shape is a promising approach for enhanced transmission through a subwavelength aperture. We designed split-ring-resonator (SRR)-shaped apertures in order to increase the transmission through subwavelength apertures by making use of the strong localization of the electromagnetic field in SRR-shaped apertures. We obtained a promising result of 104-fold enhancement by utilizing SRR-shaped apertures. It is possible to use these proposed structures at optical frequencies by making several modifications such as decreasing the sharpness of edges and increasing the gap width. Since SRRs are already being realized at optical frequencies, our proposed SRR-shaped aperture structures are promising candidates for novel applications.
Open Access
Fourier transform plasmon resonance spectrometer
(2017-01) Aibek uulu, Doolos
Nanophotonics is an emerging field of research aiming to control interaction of light with matter in nanometer scale. Electrons localized on metallic nanoparticles generate localized plasmon oscillations with interesting optical properties that can be used for various sensing applications. Spectroscopic sensing using plasmonic particles could provide more detailed information, however it requires bulky spectrometers which limits its applications. In this thesis, a nanometer scale Fourier Transform Plasmon Resonance (FTPR) spectrometer is presented. FTPR spectrometer consists of a nanometer slit-grove or slit-ridge plasmon interferometer with varying optical path. The inherent coherence of the surface plasmons propagating through the sub-wavelength holes yield high contrast spatial interference pattern. FTPR spectrometer converts this spatial interference pattern in to spectroscopic information using Fast Fourier Transform (FFT) algorithm. In our design, there is no need for a bulky dispersive spectrometer or dispersive optical elements. We anticipate that high sensitivity of surface plasmons together with spectroscopic information and nanometer dimensions provides new avenues for plasmonic sensors.
Open Access
Graphene-quantum dot hybrid optoelectronics at visible wavelengths
(American Chemical Society, 2018) Salihoglu, O.; Kakenov, N.; Balci, O.; Balci, S.; Kocabas, C.
With exceptional electronic and gate-tunable optical properties, graphene provides new possibilities for active nanophotonic devices. Requirements of very large carrier density modulation, however, limit the operation of graphene based optical devices in the visible spectrum. Here, we report a unique approach that avoids these limitations and implements graphene into optoelectronic devices working in the visible spectrum. The approach relies on controlling nonradiative energy transfer between colloidal quantum-dots and graphene through gate-voltage induced tuning of the charge density of graphene. We demonstrate a new class of large area optoelectronic devices including fluorescent display and voltage-controlled color-variable devices working in the visible spectrum. We anticipate that the presented technique could provide new practical routes for active control of light-matter interaction at the nanometer scale, which could find new implications ranging from display technologies to quantum optics.
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.
Open Access
How can we use nanophotonics to help in combating climate change?
(IEEE, 2008-08) Demir, Hilmi Volkan
The paper is about emerging technologies enabled by nanophotonics to combat climate change. We developed and demonstrated 1.) nanocrystal hybridized white light sources and those also embedded with plasmonic metal nanoparticles for the reduction of global energy consumption, 2.) photovoltaic nanocrystal scintillators hybridized on solar cells for the generation of efficient green energy sources, and 3.) photocatalytic nanoparticle and nanocomposite systems for massive environmental decontamination, all to contribute to the reduction of greenhouse gas amount.
Open Access
Macroscopic photoconductive nanowire arrays
(IEEE, 2011) Bayındır, Mehmet; Yaman, Mecit; Özgür, Erol; Aktaş, Ozan; Khudiyev, Tural; Kanık, Mehmet; Deniz, Hakan
A novel high-throughput fabrication technique to produce polymer embedded functional chalcogenide nanowire arrays is demonstrated. Indefinitely-long selenium nanowire arrays are obtained and their size dependent photoconductivity is investigated. Logarithmic increase in photo-conductance is observed. © 2011 IEEE.
Open Access
Modulation in InAs quantum dot waveguides
(Optical Society of America, 2007) Akca, B. Imran; Dana, Aykutlu; Aydınlı, Atilla; Rossetti, M.; Li L.; Fiore, A.; Dagli, N.
Modulation in molecular beam epitaxy grown self-assembled InAs quantum dot waveguides have been studied at 1500 nm as a function of wavelength and voltage. Enhanced electro-optic coefficients compared to bulk GaAs were observed. © 2007 Optical Society of America.
Open Access
Photonic crystal based multi-mode high-qcavity
(IEEE, 2011) Akosman, Ahmet Emin; Mutlu, Mehmet; Kurt H.; Özbay, Ekmel
An optical race-track has been investigated in order to obtain a multi resonant structure with high-Q factors. Photonic crystal based structure provides strong field confinement and scalability in the dimensions of the structure. The average value of the quality factors at the resonances have been calculated to be on the order of ∼105. © 2011 IEEE.
Open Access
Photonic devices and systems embedded with nanocyrstals
(SPIE, 2006) Demir, Hilmi Volkan; Soğancı, Ibrahim Murat; Mutlugun, Evren; Tek, Sümeyra; Huyal, Ilkem Ozge
We review our research work on the development of photonic devices and systems embedded with nanocyrstals for new functionality within EU Phoremost Network of Excellence on nanophotonics. Here we report on CdSe/ZnS nanocrystalbased hybrid optoelectronic devices and systems used for scintillation to enhance optical detection and imaging in the ultraviolet range and for optical modulation via electric field dependent optical absorption and photoluminescence in the visible. In our collaboration with DYO, we also present photocatalytic TiO2 nanoparticles incorporated in solgel matrix that are optically activated in the ultraviolet for the purpose of self-cleaning.
Open Access
Tight-binding mechanism in slow light regime
(IEEE, 2011) Akosman, Ahmet Emin; Mutlu, Mehmet; Kurt, Hamza; Özbay, Ekmel
In this study, tight-binding formalism is applied to a photonic crystal coupled cavity structure in order to investigate the characteristics of ultra slow light modes. Eigen-mode splitting is observed and resulting group indices obtained from the tight-binding formalism and numerical results are compared. © 2011 IEEE.
Open Access
Ultrasensitive label-free microcavity biosensors with high selectivity
(IEEE, 2011) Özgür, Erol; Bayındır, Mehmet; Aktaş, Ozan
High quality factor whispering gallery mode microresonators have been recently shown to exhibit detection sensitivity of single molecule; however, the selectivity of these sensors among different types of analytes remains as an important issue, obscuring the broad applicability of optical microcavities. We demonstrate a surface modification strategy for fabrication of high selectivity and sensitivity microcavity biosensors in this study. © 2011 IEEE.