Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Article Citation - WoS: 1Citation - Scopus: 1Simultaneous Low Noise Radio Frequency Tone and Narrow Linewidth Optical Comb Generation From a Regeneratively Mode-Locked Laser(SPIE - Society of Photo-Optical Instrumentation Engineers, 2014-10-29) Ozdur, Ibrahim; Ozharar, Sarper; Delfyett, Peter J.A regeneratively mode-locked laser with simultaneous low noise radio frequency (RF) tone and optical comb generation is presented. The laser does not need any external RF signal and emits a pulse train at similar to 10 GHz repetition rate with a 1.5-ps optical pulse width after compression. The generated RF tone has a signal-to-noise ratio of 121 dB/Hz and an RF fluctuation of 10(-9) over 0.1 s. The optical frequency comb spacing is also at similar to 10 GHz and the optical comb tooth has a linewidth of <1 kHz. (C) 2014 Society of Photo-Optical Instrumentation Engineers (SPIE)Article Citation - WoS: 1Citation - Scopus: 1RF Phase Noise Filtering Properties of an Actively Mode-Locked Laser(Wiley, 2018-01-10) Mbonde, Hamidu; Ozharar, Sarper; Ozdur, IbrahimIn 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.Article Multifunction Optoelectronic Gate(Wiley-Blackwell, 2015-02-24) Ozharar, Sarper; Ozdur, Ibrahim; Delfyett, Peter J.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. (c) 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:969-972, 2015Conference Object Citation - WoS: 3Citation - Scopus: 5Field Test and Fading Measurement of a Distributed Acoustic Sensor System Over a 50 Km-Long Fiber(Spie-Int Soc Optical Engineering, 2018-05-14) Uyar, Faruk; Kartaloglu, Tolga; Ozdur, Ibrahim; Ozbay, EkmelIn this study, we present a direct detection distributed acoustic sensor based on phase-sensitive optical time domain reflectometer (phi-OTDR) with long sensing range and high signal-to-noise ratio (SNR), which is field-tested over a 50 km-long fiber. Due to the random nature of Rayleigh backscattered light and fading phenomena, it is hard to characterize the performance of the system. For this reason, the performance of our sensor is specified in a statistical manner in which the mean SNR is determined using the histograms of the SNR. The SNR values are measured for identical acoustic signals in five different days, total of 48 hours and the SNR histograms are obtained for fiber distances of 100 m, 12 km, 21 km, 30 km, 40 km and 50 km. The system is field-tested using external disturbances that are generated from a 50-Hz vibrator. The SNR values are extracted from the power spectral density (psd) of the collected data over the monitored fiber span. Our results show that the phi-OTDR system exhibits a mean SNR of 22.5 dB at 50 km distance.Article Citation - WoS: 2Citation - Scopus: 2Analysis of Oscillator Phase Noise Effect on High Order QAM Links(Springer, 2020-08-05) Bicici, Cagri; Ozdur, Ibrahim; Cerezci, OsmanIn this work, the effect of oscillator phase noise on the bit error rate (BER) for high order QAM communication systems is analyzed. Two high frequency oscillators are designed, built and tested to get real phase noise data, and a BER simulation of a 1024 QAM signal through a super-heterodyne frequency down-converter is implemented using the measured data from the two oscillators as local oscillator sources for the down-converter. A third frequency source is also added to the simulation to visualize the dramatic effect of phase noise on the system BER analysis.Article Citation - WoS: 5Citation - Scopus: 5Amplitude Noise Suppression by Intracavity Phase Modulation in a Harmonically Mode-Locked Laser(Elsevier Sci Ltd, 2018-09) Ozharar, Sarper; Ozdur, IbrahimA 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.