Elektrik - Elektronik Mühendisliği Bölümü Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/202

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Absolute phase noise analysis of a harmonically modelocked semiconductor laser
(Optica Publishing Group (formerly OSA), 2017) Ozharar, Sarper; Ozdur, Ibrahim; 0000-0001-6452-0804; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Ozdur, Ibrahim
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.
Amplitude noise suppression by intracavity phase modulation in a harmonically mode-locked laser
(ELSEVIER SCI LTD, THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND, 2018) Ozharar, Sarper; Ozdur, Ibrahim; 0000-0001-6452-0804; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü
A fiber coupled semiconductor ring laser that employs both an amplitude and a phase modulator was built and actively harmonic mode-locked at a repetition rate of 10 GHz. The phase modulator was driven at the cavity fundamental frequency and its effects on the optical spectrum and the optical pulse train were analyzed. The intracavity phase modulation at the cavity fundamental frequency resulted in 40% lower optical pulse amplitude fluctuations and improved the stability of the optical spectrum. (C) 2018 Elsevier Ltd. All rights reserved.
The Effects of Intracavity Phase Modulation and Extracavity Optical Filtering on Amplitude Noise of Mode-Locked Pulse Trains
(IEEE, 345 E 47TH ST, NEW YORK, NY 10017 USA, 2018) Ozharar, Sarper; Ozdur, Ibrahim; 0000-0001-6452-0804; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü
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.
Experimental analysis of absolute phase noise of a harmonically mode-locked semiconductor laser
(NATL INST OPTOELECTRONICS, 1 ATOMISTILOR ST, PO BOX MG-5, BUCHAREST-MAGURELE 76900, ROMANIA, 2018) Ozharar, S.; Ozdur, I.; 0000-0001-6452-0804; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü
In this work, we have designed and experimentally characterized the absolute phase noise of a fiber coupled semiconductor ring laser at 1550 nm, actively mode-locked at 10 GHz by an external RF oscillator. The dependency of mode-locked laser phase noise to the external RF oscillator phase noise and laser cavity length is investigated using different RF sources and cavity lengths. A timing jitter of 14.6 fs (1 kHz to 1 MHz) has been measured at 10 GHz with a total cavity length of 315 meters.
Fotonik Fener Tabanlı Eş‐Fazlı Alıcı Performans Analizi
(TUBİTAK, 2016) Özdür, İbrahim Tuna; 0000-0001-6452-0804; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Özdür, İbrahim Tuna
Bos uzay es fazlı algılama sistemlerinin performanslarını arttırmak için fotonik fenerli sistemler önerilmistir (US 9322992 ). Bu projede fotonik fenerli es fazlı alıcıların sistem performansına nasıl katkı yaptıkları incelenmis ve sonrasında sistem seviyesinde nasıl gelistirmelere sebep olacagı arastırılmıstır. Bu çalısma sonucunda fotonik fener tabanlı sistemlerin sinyal gürültü oranına önemli sekilde katkı sagladıkları bulunmustur. Bu sinyal gürültü oranındaki gelisimi asıl önemli parametre olan hata oranına çevirmek için yogun çalısmalarda bulunulmus ve sonuçlar proje raporunda sunulmustur. Hata oranındaki degisim farklı optik güçlerde farklı degerlerde olmustur. Örnegin 250 mW gönderilen optik güç için hata oranı kabul edilmeyen %40 dan, bu tarz sistemler için kabul edilebilir olan %10 seviyesine indirilmistir. Ayrıca fotonik fenerlerin agırlık güç tüketimi gibi parametrelere katkısı da arastırılmıs ve en büyük katkılarının aynı performans için gereken 1.5 kat daha kısa çapı olan optik lens oldugu degerlendirilmistir.
Multifunction optoelectronic gate
(WILEY, 2015) Ozdur, Ibrahim Tuna; Ozharar, Sarper; Delfyett, Peter J.; 0000-0001-6452-0804; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Ozdur, Ibrahim Tuna
A multifunction optoelectronic gate that can perform as any desired logic gate of two variables was theoretically proposed and a simplified version is experimentally demonstrated. The proposed optoelectronic gate is dynamically configurable, and being wavelength independent, it can act on multiple input optical bits and realize different functions simultaneously.
Optical detection of microplastics in water
(SPRINGER HEIDELBERGTIERGARTENSTRASSE 17, D-69121 HEIDELBERG, GERMANY, 2021) Iri, Ahmet H.; Shahrah, Malek H. A.; Ali, Ali M.; Qadri, Sayed A.; Erdem, Talha; Ozdur, Ibrahim T.; Icoz, Kutay; 0000-0001-6452-0804; 0000-0003-3905-376X; 0000-0002-0947-6166; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; 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 Tuna; 0000-0001-6452-0804; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Ozdur, Ibrahim Tuna
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.
Performance improvements of photonic lantern based coherent receivers
(IEEE, 2014) Ozdur, Ibrahim Tuna; Toliver, Paul; Woodward, T. K.; 0000-0001-6452-0804; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Ozdur, Ibrahim Tuna
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.
RF phase noise filtering properties of an actively mode-locked laser
(WILEY, 111 RIVER ST, HOBOKEN 07030-5774, NJ USA, 2018) Mbonde, Hamidu; Ozharar, Sarper; Ozdur, Ibrahim; 0000-0001-6452-0804; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü
In this article, we are presenting the experimental results and theoretical analysis of radio frequency (RF) phase noise filtering properties of a high Q cavity actively driven mode-locked laser. The experimental results show that, the phase noise of a 10 GHz RF tone can be filtered by at least 10 dB at 200 kHz offset frequency. A theoretical analysis on the limits of phase noise filtering due to the spontaneous emission and the frequency mismatch between the laser cavity modes and the synthesizer frequency is also included.
Use of laser-induced bubbles in intraocular pressure measurement: a preliminary study
(IOP PUBLISHING LTD, TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND, 01.01.2019) Altindis, Fatih; Ozdur, Ibrahim T.; Mutlu, Sait N.; Yilmaz, Bulent; 0000-0002-3891-935X; 0000-0001-6452-0804; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü
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.

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