Browsing by Subject "Quality factors"

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    ItemOpen Access
    Chalcogenide microresonators tailored to distinct morphologies by the shaping of glasses on silica tapers
    (OSA - The Optical Society, 2017) Aktaş, O.
    Production of chalcogenide (As2Se3) microresonators in sphere, loop, and bottle morphologies by the shaping of glasses at appropriate temperatures between cleaved silica tapers is reported. The quality factors exceed QS = 6.2×105, QB = 6.7 × 105, and QL = 1.6 × 104 for the sphere, bottle, and loop microresonators, respectively. All-optical thermally assisted tuning with a rate of 0.61 nm/mW is demonstrated for a bottle microcavity pumped via a silica taper at a wavelength of 670 nm. This technique enables practical and robust in situ production of chalcogenide microresonators thermally spliced to silica fibers in several morphologies with a wide tuning range of size.
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    Designing transmitting CMUT cells for airborne applications
    (Institute of Electrical and Electronics Engineers Inc., 2014) Ünlügedik, A.; Taşdelen, A.; Atalar, Abdullah; Köymen, Hayrettin
    We report a new mode of airborne operation for capacitive micromachined ultrasonic transducers (CMUT), in which the plate motion spans the entire gap without collapsing and the transducer is driven by a sinusoidal voltage without a dc bias. We present equivalent-circuit-based design fundamentals for an airborne CMUT cell and verify the design targets using fabricated CMUTs. The performance limits for silicon plates are derived. We experimentally obtain 78.9 dB//20 μPa@1 m source level at 73.7 kHz, with a CMUT cell of radius 2.05 mm driven by 71 V sinusoidal drive voltage at half the frequency. The measured quality factor is 120. We also study and discuss the interaction of the nonlinear transduction force and the nonlinearity of the plate compliance. © 1986-2012 IEEE.
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    Gaziantep'te Sedef Kakma Sanatı ve Sedefkarlık
    (Bilkent University, 2019) Tercan, Furkan Ataberk; Coşar, Ayşe Ada; Samim, Ecem
    Uzun yıllardır Anadolu insanın el emeğini, el sanatlarına olan ilgisini ve zevkini yansıtan Sedef Kakma sanatı. Türkiye'de ve özellikle Gaziantep ilinde sürdürülmektedir. Bu araştırmada Türkiye'deki tarihçesinden, uygulanan farklı türlerdeki metotlardan, kullanılan özel malzemelerden bahsedilerek Gaziantep ilindeki özelliklerine indirgenmesi amaçlanmıştır. Bu indirgenme sonucu sedef kakma sanatının ve sedefkarlığın Gaziantep ilindeki tarihçesi, yıllar içerisindeki değişimi ve gördüğü değer kapsamı, usta çırak ilişkini, bu sanatın ve bunu uygulayan sanatçıların Gaziantep ekonomisine ve kendi ekonomik durumlarına katkısı, yaşanılan değer kaybı sonrası tekrardan bunu kazanması için yapılan devam çalışmaları ve Gaziantep ilinde yapılan sedef kakma sanatıyla yapılan ürünlerin neler olduğu ve bu ürünlerin kullanım amaçlarının işlenmesi bu araştırma raporunda işlenmesi amaçlanmıştır. Bunun yanı sıra Gaziantep ilinde yaşayan ve sedef kakma sanatını uzun yıllardır bu sanatı mesleği olarak gören 2 sedefkar ustası ve yine uzun yıllardır bu sanatla uğraşan ve Gaziantep Olgunlaşma Enstitüsünde bu sanat üzerine eğitim veren bir sedefkar ustası ile yapılan röportajlar bu araştırma raporunda kapmasa altına alınmıştır.
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    ItemOpen Access
    Grating based plasmonic band gap cavities
    (Optical Society of American (OSA), 2009-08) Şenlik, S. Seçkin; Kocabaş, Aşkın; Aydınlı, Atilla
    We report on a comparative study of grating based plasmonic band gap cavities. Numerically, we calculate the quality factors of the cavities based on three types of grating surfaces; uniform, biharmonic and Moiré surfaces. We show that for biharmonic band gap cavities, the radiation loss can be suppressed by removing the additional grating component in the cavity region. Due to the gradual change of the surface profile in the cavity region, Moiré type surfaces support cavity modes with higher quality factors. Experimentally, we demonstrate the existence of plasmonic cavities based on uniform gratings. Effective index perturbation and cavity geometries are obtained by additional dielectric loading. Quality factor of 85 is obtained from the measured band structure of the cavity. © 2009 Optical Society of America.
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    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.