Browsing by Author "Akosman, Ahmet Emin"

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Open Access
Bar-supported negative curvature hollow-core fiber for low-loss guidance in the near-infrared region
(IEEE, 2024-12-31) Fatima, Arooj; Akosman, Ahmet Emin; Ordu, Mustafa
A novel negative curvature hollow-core optical fiber with bar-supported tubular structures is proposed. The five sets of cladding elements improved the transmission in the near-infrared region as low as 0.0014 dB/km with strong single-mode guidance.
Open Access
Design of compact optical devices based on periodic meta-structures
(2013) Akosman, Ahmet Emin
Manipulation of the flow of light is demanded for several applications such as communication, data storage, sensor, photovoltaic cells, microscopy, lasers and light emitting diodes for the purpose of designing compact, high-throughput and high efficiency optical devices. Nevertheless, the control of the propagation of the light becomes much harder in devices with smaller geometries mostly because of diffractions, loss mechanisms and fabrication difficulties. Furthermore, materials that are already available in the nature do not provide unprecedented optical properties for nanoscale optical applications. Due to this fact that fabrication of artificial materials is needed for utilizing novel and intriguing optical devices. For this purpose, some relatively new research fields have emerged like photonic crystals, metamaterials and high contrast gratings. We propose several designs based on aforementioned meta-structures to achieve compact and practically realizable optical devices. We presented compact optical demultiplexer, diode-like device and electro-optic modulator designs that are based on photonic crystals. We also proposed two circular polarizer designs based on metamaterials and high contrast gratings. Further, we investigated unidirectional transmission and polarization manipulation properties in chiral metamaterials. For most of the proposed designs, we also experimentally verified the numerical and theoretical findings. In conclusion, we can claim that the utilization of artifically structured materials give opportunity to realize the control of light much more easily in nanoscale designs.
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
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.