arXiv subjects

Burak Gerislioglu

Publications and source records attributed to Burak Gerislioglu.

12 recordsLinked to original sources

arXiv2020

Femtomolar-level detection of SARS-CoV-2 spike proteins using toroidal plasmonic metasensors

Effective and efficient management of human betacoronavirus severe acute respiratory syndrome (SARS)-CoV-2 infection i.e., COVID-19 pandemic, required sensitive sensors with short sample-to-result durations for performing diagnostics. In this direction, one of appropriate alternative approach to detect SARS-CoV-2 at low level (fmol) is exploring plasmonic metasensor technology for COVID-19 diagnostics, which offers exquisite opportunities in advanced healthcare programs, and modern clinical diagnostics. The intrinsic merits of plasmonic metasensors stem from their capability to squeeze electromagnetic fields, simultaneously in frequency, time, and space. However, the detection of low-molecular weight biomolecules at low densities is a typical drawback of conventional metasensors that has recently been addressed using toroidal metasurface technology. This research reports fabrication of a miniaturized plasmonic immunosensor based on toroidal electrodynamics concept that can sustain robustly confined plasmonic modes with ultranarrow lineshapes in the terahertz (THz) frequencies. By exciting toroidal dipole mode using our quasi-infinite metasurface and a judiciously optimized protocol based on functionalized gold nanoparticles (NPs) conjugated with the specific monoclonal antibody of SARS-CoV-2 onto the metasurface, the resonance shifts for diverse concentrations of the spike protein is monitored. Possessing molecular weight around ~76 kDa allowed us to detect the presence of spike protein with significantly low LoD ~4.2 fmol.

physics.optics↗

arXiv2019

Electrically Driven Hot-Carrier Generation and Above-threshold Light Emission in Plasmonic Tunnel Junctions

Above-threshold light emission from plasmonic tunnel junctions, when emitted photons have energies significantly higher than the energy scale of the incident electrons, has attracted much recent interest in nano-optics, while the underlying physical mechanism remains elusive. We examine above-threshold light emission in electromigrated tunnel junctions. Our measurements over a large ensemble of devices demonstrate a giant material dependence of photon yield (emitted photons per incident electrons), as large as four orders of magnitude. This dramatic effect cannot be explained only by the radiative field enhancement effect due to the localized plasmons in the tunneling gap. Emission is well described by a Boltzmann spectrum with an effective temperature exceeding 2000 K, coupled to a plasmon-modified photonic density of states. The effective temperature is approximately linear in the applied bias, consistent with a suggested theoretical model in which hot carriers are generated by non-radiative decay of electrically excited localized plasmons. Electrically driven hot-carrier generation and the associated non-traditional light emission could open new possibilities for active photochemistry, optoelectronics and quantum optics.

cond-mat.mes-hall↗

arXiv2019

Photoluminescence spectroscopy of hybridized exciton-polariton coupling in silicon nanodisks with nonradiative anapole radiations

Semiconductor nanoparticles and nanostructures in the strong coupling regime exhibit an intriguing energy scale in the optical frequencies, which is specified by the Rabi splitting between the upper and lower exciton-polariton states. Technically, exciton-polaritons are part-light, part-matter quasiparticles that arise from the strong interaction of excitonic substances and photonic platforms. In this work, using full-wave numerical and theoretical studies, we showed the emergence of strong light-matter coupling between the nonradiating anapole states from an individual semiconductor nanodisk coupled to a J-aggregate fluorescent dye molecule resonating in the visible spectrum. By demonstrating the physical mechanism behind the observed energy splitting for various Lorentzian linewidth of excitonic material, we theoretically confirmed the obtained spectral responses by conducting photoluminescence spectroscopy analysis. The coupling of anapole resonances in semiconductor nanoparticles with excitonic levels can propose interesting possibilities for the control of directional light scattering in the strong coupling limit, and the dynamic tuning of deep-subwavelength light-matter coupled states by external stimuli.

physics.optics↗

arXiv2019

Towards infrared toroidal photodevices: A Review

Plasmon excitations in metallic nanostructures can decay directly into dynamic electron-hole pairs (EHPs), exploitable for photocurrent generation. This approach has extensively been employed to develop nanoplasmonic light-sensing devices with significant responsivity and quantum efficiency. Of particular interest is infrared plasmonic photodetectors with a wide range of technological applications, including spectroscopy, biosensing, and surveillance. This Review discusses fundamentals, recent advances, and trending mechanisms in the understanding and applications of plasmon-enhanced photocurrent generation in nanostructures across the infrared spectrum. By highlighting and comparing the developed techniques, we demonstrate the newly introduced directions toward achieving high-photon yield infrared plasmonic photodetection tools. As a promising concept in modern photonics, we represent the emergence of toroidal meta-atoms as plasmon-induced carrier generators with unconventionally exquisite properties for designing advanced, rapid, and next-generation plasmonic photodetectors with significantly high responsivity and photocurrent.

physics.optics↗

arXiv2019

Ultraprecise Detection of Low Molecular Weight Antibodies Using Mid-IR Toroidal Plasmonic Meta-Atoms

Plasmonic metamaterials can be used to enhance mid-infrared sensors and detectors for immunosensing applications. The major challenge is to integrate these technologies in low-cost, compact, and promising platforms. In this study, as an emerging approach, we utilized toroidal resonant plasmonic metasurfaces to develop an ultrasensitive label-free analytical platform for the detection of specific antibiotics in the mid-IR regime. Taking advantage of unique sensitivity of robustly squeezed electromagnetic fields in toroidal meta-atoms, we validated that our proposed technique based on toroidal metastructures can provide sensing of biological targets with the weight of ~0.6 KDa at attomolar concentrations. We believe that this understanding extends the capabilities of plasmonic metamaterials analyze the presence of specific biological targets with high precision.

physics.optics↗

arXiv2018

Revealing Quantitative Observation of Multi-Loop Super-Toroidal Currents in Plasmonic Meta-Atoms

Living in a world of resonances, there have been significant progresses in the field of excitation high-quality and multifunctional moments across a wide range of optical frequencies. Among all acknowledged resonances, the toroidal multipoles have received copious interest in recent years due to having inherent signatures in nature. As a fundamental member, toroidal dipole is a strongly localized electromagnetic excitation based on charge-current distributions, which can be squeezed in an extremely tiny spot. Although there have been extensive studies on the behavior and properties of toroidal dipoles to develop all-optical devices based on this technology, so far, all analyses are restricted to the first (1st) order toroidal dipoles. In this work, using a simple technique, we successfully monitored supporting exquisite multi-loop super-toroidal (MLST) spectral features in a planar multipixel plasmonic meta-atom. We quantitatively demonstrate that how a traditional toroidal dipole can be switched to a super-toroidal moment by varying the dielectric permittivity of the gaps between proximal pixels. This understanding paves new approaches for the excitation of complex multi-loop toroidal moments in plasmonic metamaterials with high sensitivity, applicable for various practical applications.

physics.optics↗

arXiv2018

Toroidal Plasmonic Meta-Biosensors: Benchmarking against Classical Plasmonic Biosensors and Transducers

Rapid progress in plasmonics biosensors and immunosensors brings many methodologies to employ resonant subwavelength structures associated with the physics of multipoles, Fano resonances, and analogous moments. Here, we review a broad range of traditional and novel techniques that have been utilized for developing advanced biosensing tools including colloidal nanoparticles (NPs)-based systems to well-engineered arrays of meta-atoms and metamolecules. By describing some of the important and practical label-free biosensing methods based on subwavelength plasmonic technology, we discuss the emerging and excitation of toroidal multipoles concept, as a third family of multipolar modes, has made a revolution in enhancing the sensing performance of ultra-low weight diseases proteins and viruses as biological targets. Taking the exquisite and untraditional advantages of toroidal plasmonic metasurfaces, we comprehensively evaluated the detection properties and high-quality of toroidal immunosensors for the sensing of signature of bioproteins at picomolar (pM) concentrations with excellent limit of detection (LOD). This understanding clearly shows how toroidal metasensors have emerged as promising clinical and pharmacology tools, can be considered as alternatives and big competitors for conventional plasmonic sensors and transducers.

physics.app-ph↗

arXiv2018

Directional toroidal dipoles driven by oblique poloidal current flows in plasmonic meta-atoms

The toroidal dipole is an exquisite electromagnetic momentum apart from the classical multipoles family that can be localized and squeezed in an extremely tiny spot. This mode, in optical nanosystems, can be particularly distinguished as a non-radiating charge-current configuration, manifests in a head-to-tail fashion. Here going beyond conventional toroidal dipoles, we explained the possibility of the excitation of directional toroidal dipoles in plasmonic meta-atoms driven by controlling the oblique poloidal fluxes. We showed that the unique structural properties of the proposed asymmetric design lead to the formation of multiple toroidal modes with opposite poloidal current flows.

physics.optics↗

arXiv2018

Selective High-Harmonic Generation by Charge Transfer Plasmon-Resonant Nanodimers

Here, we study the possibility of selective high-harmonic generation (HHG) based on the concept of charge transfer plasmons (CTP) in bridged nanoparticle assemblies. By choosing plasmonic dimer nanoantenna, as a fundamental member of nanoclusters family, and bridging the gap space between the proximal nanoparticles with an optothermally controllable substance, we selectively produced two different harmonics at different states of the functional bridge. To this end, the conductive connection between the nanoparticles is mediated with Ge2Sb2Te5 (GST), which inherently has opposite optical and electrical properties depending on its phase condition. This helped us to manipulate the transition of charges across the bridge and therefore, control the excitation of CTP resonances and provide a switching feature between distinguished plasmonic resonant modes. Such a control allows us to produce highly intense second and forth harmonics based on the conductivity of the interparticle junction.

physics.optics↗

arXiv2017

Tunable Plasmonic Toroidal Terahertz Metamodulator

Optical modulators are essential parts of photonic circuits to encode electro-optical signals to the optical domain. Here, using arrays of multipixel toroidal plasmonic terahertz (THz) metamolecules, we developed a plasmonic metamodulator with high efficiency and tunability. Using the ultrasensitivity of the excited toroidal momentum to the incident THz beam power, we numerically and experimentally studied the plasmonic response of the proposed device. We showed that the proposed THz toroidal metamodulator have strong potential to be employed for practical advanced communication applications.

physics.optics↗

arXiv2017

Thermally Controllable Multiple High Harmonics Generation by Phase-Change Materials-Mediated Fano Clusters

Substantial enhancement of nonlinear high-order harmonics generation based on Fano-resonant nanostructures has received growing interest due to their promising potential for developing integrated and advanced next-generation nanophotonic devices. In this study, going beyond conventional subwavelength structures, we propose an optothermally functional hetero-metallodielectric asymmetric eight-member octamer cluster composed of a central silicon nanodisk and peripheral disks with a phase-change material (Ge2Sb2Te5). Using full electromagnetic calculations, we show that in the amorphous phase of the surrounding particles, the oligomer acts as an all-dielectric cluster, while in the crystalline regime, the octamer turns into a hybrid metallodielectric assembly. Exploiting the exquisite ability of supporting distinct Fano lineshapes at different wavelengths depending on the phase of Ge2Sb2Te5, we showed the generation of both second and third harmonics at amorphous and crystalline phases of GST nanodisks, respectively with the produced harmonic wavelengths of 425 nm and 317 nm, respectively. Our calculations for the corresponding conversion efficiencies revealed significant enhancements as {\eta}SHG=0.012% and {\eta}THG=0.0081% for SHG and THG, respectively. Such an exquisite feature of multiresonant optothermally tunable cluster allows generation of several higher-harmonics with distinct intensities using a single system for future photonics applications.

physics.optics↗

arXiv2017

Optothermally Controlled Charge Transfer Plasmons in Au-Ge2Sb2Te5 Core-Shell Assemblies

Tunable plasmonic resonances across the visible and near infrared spectra have provided novel ways to develop next-generation nanophotonic devices. In this study, by using optothermally controllable phase-changing material (PCM), we successfully induced highly tunable charge transfer plasmon (CTP) resonance modes. To this end, we have designed a two-member dimer assembly including gold cores and Ge2Sb2Te5 (GST) shells in distant, touching, and overlapping conditions. We successfully demonstrated that toggling between amorphous (dielectric) and crystalline (conductive) phases of GST allows for achieving tunable dipolar and CTP resonances along the near-infrared spectrum. The proposed dimer structures can help forming optothermally controlled devices without further geometrical variations in the geometry of the design, and having strong potential for advanced plasmon modulation and fast data routing.

physics.optics↗