Browsing by Author "Unlu, S."

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Open Access
High-speed GaAs-based resonant-cavity-enhanced 1.3 μm photodetector
(American Institute of Physics., 2000) Kimukin, I.; Özbay, Ekmel; Bıyıklı, Necmi; Kartaloğlu, T.; Aytür, O.; Unlu, S.; Tuttle, G.
We report GaAs-based high-speed, resonant-cavity-enhanced, Schottky barrier internal photoemission photodiodes operating at 1.3 μm. The devices were fabricated by using a microwave-compatible fabrication process. Resonance of the cavity was tuned to 1.3 μm and a nine-fold enhancement was achieved in quantum efficiency. The photodiode had an experimental setup limited temporal response of 16 ps, corresponding to a 3 dB bandwidth of 20 GHz. © 2000 American Institute of Physics.
Open Access
High-speed transparent indium-tin-oxide based resonant cavity Schottky photodiode with Si/sub 3/N/sub 4//SiO/sub 2/ top Bragg mirror
(IEEE, Piscataway, NJ, United States, 2000) Bıyıklı, Necmi; Kimukin, I.; Aytur, O.; Özbay, Ekmel; Gokkavas, M.; Unlu, S.
Photodetectors demonstrating high bandwidth-efficiency (BWE) products are required for high-performance optical communication and measurement systems. For conventional photodiodes the BWE product is limited due to the bandwidth-efficiency trade-off. A resonant cavity enhanced (RCE) photodetection scheme offers the possibility to overcome this limitation. Very high BWE products are achieved using Schottky and p-i-n type RCE photodiodes, which could not be reached with conventional detector structures. Even better performances should be possible for RCE Schottky photodiodes if one can get rid of the optical losses and scattering caused by the Schottky metal, Au, which also serves as the top mirror of the resonant cavity. The transparent, low resistivity material indium-tin-oxide (ITO) is a potential alternative to thin semi-transparent Au as a Schottky-barrier contact material. We report our work on high-performance ITO-based RCE Schottky photodiodes.
Open Access
Perinatology clinic in the coronavirus disease-2019 pandemic: What harms, often teaches
(Taylor & Francis, 2021-02-28) Yapar Eyi, E.G.; Moraloglu Tekin, O.; Buğlagil, Arda; Sahin, D.; Yucel, A.; Tanacan, A.; Halici Ozturk, F.; Yakistiran, B.; Yucel Yetiskin, D.; Unlu, S.; Gokcinar, D.
Compartmental models simplify the mathematical modeling of infectious diseases based on reported cases. In the absence of precautions, personal protective equipment, quarantine and social distancing, a Susceptible–Exposed–Infectious–Recovered (SuEIR) model with Unscented Kalman Filter for coronavirus disease-19 (COVID-19) Forecasts in Turkey has revealed 174 641 infected people on August 15, 2020, whilst the reported case was 12 216. Through numerical experiments, the effects of quarantine, social distancing, and COVID-19 testing on the dynamics of the outbreak varies. We herein present the documentation of the work in a perinatology clinic during COVID-19 pandemic to find the reflection in a pandemic hospital as even in the pandemic, pregnancy complications and fetal diagnosis/therapy are time-sensitive and cannot be delayed. During the prevention of the horizontal transmission to the health-care workers (HCWs), testing all pregnant women with nasopharyngeal/oropharyngeal swabs for severe acute respiratory syndrome coronavirus (SARS-COV-2) undergoing birth, ultrasound examinations, invasive procedures appear to be the gold standard so that appropriate precautions can be taken if the screen is positive. Though it is logical, it may be incompatible with a busy obstetric practise as a pending polymerase chain reaction (PCR) result should never delay any emergent procedure.