WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394
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Article Disorder-Engineered Hybrid Plasmonic Cavities for Emission Control of Defects in HBN(American Chemical Society, 2026-02-07) Genc, Sinan; Yucel, Oguzhan; Aglarci, Furkan; Rodriguez-Fernandez, Carlos; Yilmaz, Alpay; Caglayan, Humeyra; Bek, AlpanDefect-based quantum emitters in hexagonal boron nitride (hBN) are promising building blocks for scalable quantum photonics due to their stable single-photon emission at room temperature. However, enhancing their emission intensity and controlling the decay dynamics remain significant challenges. This study demonstrates a low-cost, scalable fabrication approach to integrate plasmonic nanocavities with defect-based quantum emitters in hBN nanoflakes. Using the thermal dewetting process, we realize two distinct configurations: stochastic Ag nanoparticles (AgNPs) on hBN flakes and hybrid plasmonic nanocavities formed by AgNPs on top of hBN flakes supported on gold/silicon dioxide (Au/SiO2) substrates. While AgNPs on bare hBN yield up to a 2-fold photoluminescence (PL) enhancement with reduced emitter lifetimes, the hybrid nanocavity architecture provides a dramatic, up to 100-fold PL enhancement and improved uniformity across multiple emitters, all without requiring deterministic positioning. Finite-difference time-domain (FDTD) simulations and time-resolved PL measurements confirm size-dependent control over decay dynamics and cavity-emitter interactions. Our versatile solution overcomes key quantum photonic device development challenges, including material integration, emission intensity optimization, and spectral multiplexity.Article Citation - WoS: 29Citation - Scopus: 30Enhanced Transmission and Beaming via a Zero-Index Photonic Crystal(Amer Inst Physics, 2016-07-18) Hajian, Hodjat; Ozbay, Ekmel; Caglayan, HumeyraCertain types of photonic crystals with Dirac cones at the Gamma point of their band structure have a zero effective index of refraction at Dirac cone frequency. Here, by an appropriate design of the photonic structure, we obtain a strong coupling between modes around the Dirac cone frequency of an all-dielectric zero-index photonic crystal and the guided ones supported by a photonic crystal waveguide. Consequently, we experimentally demonstrate that the presence of the zero-index photonic crystal at the inner side of the photonic crystal waveguide leads to an enhancement in the transmission of some of the guided waves passing through this hybrid system. Moreover, those electromagnetic waves extracted from the structure with enhanced transmission exhibit high directional beaming due to the presence of the zero-index photonic crystal at the outer side of the photonic crystal waveguide. Published by AIP Publishing.Article Citation - WoS: 11Citation - Scopus: 13Enhanced Tunability of V-Shaped Plasmonic Structures Using Ionic Liquid Gating and Graphene(Pergamon-Elsevier Science Ltd, 2016-11) Ozdemir, Onur; Aygar, A. Melis; Balci, Osman; Kocabas, Coskun; Caglayan, Humeyra; Ozbay, EkmelGraphene is a strong candidate for active optoelectronic devices because of its electrostatically tunable optical response. Current substrate back-gating methods are unable to sustain high fields through graphene unless a high gate voltage is applied. In order to solve this problem, ionic liquid gating is used which allows substrate front side gating, thus eliminating the major loss factors such as a dielectric layer and a thick substrate layer. On the other hand, due to its two dimensional nature, graphene interacts weakly with light and this interaction limits its efficiency in optoelectronic devices. However, V-shaped plasmonic antennas can be used to enhance the incident electric field intensity and confine the electric field near graphene thus allowing further interaction with graphene. Combining V-shaped nanoantennas with the tunable response of graphene, the operation wavelength of the devices that utilize V-shaped antennas can be tuned in situ. In the present paper, we demonstrate a graphene-based device with ionic liquid gating and V-shaped plasmonic antennas to both enhance and more effectively tune the total optical response. We are able to tune the transmission response of the device for up to 389 nm by changing the gate voltage by 3.8 V in the mid-infrared regime. (C) 2016 Elsevier Ltd. All rights reserved.Article Citation - WoS: 16Citation - Scopus: 19Coupling Enhancement of Split Ring Resonators on Graphene(Pergamon-Elsevier Science Ltd, 2014-12) Cakmakyapan, Semih; Caglayan, Humeyra; Ozbay, EkmelMetallic split ring resonator (SRR) structures are used in nanophotonics applications in order to localize and enhance incident electromagnetic field. Electrically controllable sheet carrier concentration of graphene provides a platform where the resonance of the SRRs fabricated on graphene can be tuned. The reflectivity spectra of SRR arrays shift by applying gate voltage, which modulates the sheet carrier concentration, and thereby the optical conductivity of monolayer graphene. We experimentally and numerically demonstrated that the tuning range can be increased by tailoring the effective mode area of the SRR and enhancing the interaction with graphene. The tuning capability is one of the important features of graphene based tunable sensors, optical switches, and modulator applications. (C) 2014 Elsevier Ltd. All rights reserved.