Browsing by Author "Ozdur, Ibrahim T."

Now showing 1 - 10 of 10

Citation - WoS: 2
Citation - Scopus: 3
94.8 Km-Range Direct Detection Fiber Optic Distributed Acoustic Sensor
(Institute of Electrical and Electronics Engineers Inc., 2019) Uyar, Faruk; Onat, Talha; Unal, Canberk; Kartaloǧlu, Tolga; Ozdur, Ibrahim T.; Özbay, Ekmel
This work demonstrates an ultra-long range direct detection fiber optic distributed acoustic sensor which can detect vibrations at a distance of 94.8 km with 10 m resolution along the sensing fiber. © 2019 Elsevier B.V., All rights reserved.
Absolute Phase Noise Analysis of a Harmonically Modelocked Semiconductor Laser
(Optica Publishing Group (formerly OSA), 2017) Özharar, Sarper; Ozdur, Ibrahim T.
We have designed and built a fiber coupled semiconductor laser at 1550 nm, which is harmonically mode-locked at 10 GHz by an external RF oscillator. The absolute phase noise of the laser is measured and discussed for two different cavity lengths. © 2023 Elsevier B.V., All rights reserved.
The Effects of Intracavity Phase Modulation and Extracavity Optical Filtering on Amplitude Noise of Mode-Locked Pulse Trains
(Institute of Electrical and Electronics Engineers Inc., 2018) Özharar, Sarper; Ozdur, Ibrahim T.
An actively mode-locked, fiber-coupled semiconductor ring laser that employs both a phase modulator and an amplitude modulator was built. The laser was mode-locked by loss modulation at 10 GHz and the intracavity phase modulator was driven at the cavity fundamental frequency of 1.63 MHz. The effects of the intracavity phase modulation on the stability of the optical spectrum, the timing jitter, and the amplitude noise of the pulse train was analyzed. It was found that using this method, the amplitude fluctuation can be reduced by 40%, and the stability of the optical spectrum can be improved while keeping the phase noise of the system unchanged. © 2019 Elsevier B.V., All rights reserved.
Experimental Analysis of Non-Linear Phenomena due To Perturbation Amplitude in Φ-OTDR Based Fiber Optic Distributed Vibration Sensor
(Optica Publishing Group (Formerly OSA), 2020) Uyar, Faruk; Kartaloǧlu, Tolga; Özbay, Ekmel; Ozdur, Ibrahim T.
We experimentally analyze the non-linearity effect due to the perturbation amplitude in the φ-OTDR based fiber optic distributed vibration sensor by investigating the effects of large disturbance signal. © 2023 Elsevier B.V., All rights reserved.
Gain Enhancement of a mmWave Patch Antenna Array Having Limited Number of Input Ports
(Institute of Electrical and Electronics Engineers Inc., 2024) Keskin, Mehmet Ziya; Yentur, Abdulkadir; Ozdur, Ibrahim T.; Kiliç, Veli Tayfun
mmWave sensors are rapidly being used in various fields due to their low power consumption, compact size, and cost-effectiveness, particularly for applications like target detection and tracking. This study investigates the gain enhancement of a patch antenna array operating in the mmWave frequency band of 76 GHz - 81 GHz, where commercial single-chip integrated circuits are available. We analyze the S-parameters and radiation patterns of a reference antenna in detail, comparing simulation results with experimental measurements to ensure accuracy. Acknowledging the challenges posed by mmWave patch antennas, we propose a straightforward method to enhance peak gain while preserving the capabilities of the commercial patch structure. Specifically, by twinning one of the input port signals using a power divider, we increase the number of elements in the array without altering the number of input ports. Our findings suggest that this technique can increase the peak gain by 1.3 dB and narrow the beam by 4°, resulting in practical benefits such as enhanced target detection range and accuracy in radar applications while mostly preserving the functioning of the system. © 2025 Elsevier B.V., All rights reserved.
Citation - WoS: 45
Citation - Scopus: 53
Optical Detection of Microplastics in Water
(Springer Heidelberg, 2021) Iri, Ahmet H.; Shahrah, Malek H. A.; Ali, Ali M.; Qadri, Sayed A.; Erdem, Talha; Ozdur, Ibrahim T.; Icoz, Kutay
Unfortunately, the plastic pollution increases at an exponential rate and drastically endangers the marine ecosystem. According to World Health Organization (WHO), microplastics in drinking water have become a concern and may be a risk to human health. One of the major efforts to fight against this problem is developing easy-to-use, low-cost, portable microplastic detection systems. To address this issue, here, we present our prototype device based on an optical system that can help detect the microplastics in water. This system that costs less than $370 is essentially a low-cost Raman spectrometer. It includes a collimated laser (5 mW), a sample holder, a notch filter, a diffraction grating, and a CCD sensor all integrated in a 3D printed case. Our experiments show that our system is capable of detecting microplastics in water having a concentration less than 0.015% w/v. We believe that the designed portable device can find a widespread use all over the world to monitor the microplastic content in an easier and cost-effective manner.
Performance Analysis of Specialty Fiber Optic Cables for Distributed Acoustic Sensing
(Optica Publishing Group (Formerly OSA), 2020) Uyar, Faruk; Kartaloǧlu, Tolga; Erol, Mustafa; Özbay, Ekmel; Ozdur, Ibrahim T.
In this work, we present the signal-to-noise ratio comparison results of six different buried fiber optic cable for identical external perturbations using a home-made direct detection φ-OTDR system. © 2023 Elsevier B.V., All rights reserved.
Citation - WoS: 3
Citation - Scopus: 3
Performance Improvements of Photonic Lantern Based Coherent Receivers
(Institute of Electrical and Electronics Engineers Inc., 2014) Ozdur, Ibrahim T.; Toliver, Paul; Woodward, Ted K.
In this work, the signal-to-noise ratio improvement of photonic lantern-based coherent receivers over single-mode coherent receivers is demonstrated. The signal-to-noise ratio is improved by a factor of 2.8 when other parameters kept constant. © 2021 Elsevier B.V., All rights reserved.
RF Phase Noise Filtering Effects of Mode-Locked Lasers
(Optica Publishing Group (formerly OSA), 2017) Ozdur, Ibrahim T.; Özharar, Sarper
In this manuscript, we have presented the results for RF phase noise filtering effects of mode-locked lasers. Our results show that, the phase noise of a 10GHz RF tone can be filtered by 10 dB. © 2023 Elsevier B.V., All rights reserved.
Use of Laser-Induced Bubbles in Intraocular Pressure Measurement: A Preliminary Study
(IOP Publishing Ltd, 2019) Altindis, Fatih; Ozdur, Ibrahim T.; Mutlu, Sait N.; Yilmaz, Bulent
This work investigates the feasibility of a novel approach for measuring intraocular pressure (IOP) by analyzing micron-level laser-induced bubble characteristics in the intraocular fluid. We believe that this concept may be used as a non-invasive alternative for measuring a patient's IOP by analyzing the laser-induced bubble volume in the intraocular fluid in the anterior chamber of the eye. The behavior of laser-induced bubbles was examined under differing fluid pressure levels and at differing laser pulse energy levels. An intraocular medium-like environment was imitated and an imaging system was designed in order to capture laser-induced bubbles with their movements. The video recordings of the bubbles were processed using custom software, and the volume of the bubbles was estimated using three different approaches. The bubble volumes were estimated more accurately by using the rising velocity of the bubble rather than its direct radii appearances on the images. An inversely proportional relationship was observed between the laser-induced bubble volume and the fluid pressure. IOP can be measured with a non-invasive technique using laser-induced bubble volume. Deeper and detailed studies, including clinical studies, may lead to the use of lasers for measuring IOP.