Haldun Goktas | Ankara Yildirim Beyazit University (original) (raw)
Papers by Haldun Goktas
Microwave and Optical Technology Letters, 2021
In this article, we experimentally propose an efficient wide flat gain bandwidth with a parallel ... more In this article, we experimentally propose an efficient wide flat gain bandwidth with a parallel hybrid fiber amplifier. The setup includes parallel amplifier branches. In the first branch, serial erbium‐doped and Raman fiber amplifiers are used. In the second branch, only a Raman fiber amplifier is used. Three Raman pump power units (i.e., 1410, 1480, and 1495 nm) are used to achieve Raman gain at different optical communication bands. At optimum pump powers and at a small‐signal power of −30 dBm, an average gain of 18.5 dB with a maximum gain variation of 3 dB and a gain flatness bandwidth of 83 nm, that is, from 1527 to 1610 nm, is achieved. This gain flatness is expanded to 92 nm (1525–1617 nm) at a large input signal power of −5 dBm with an average gain level of 13 dB. In our proposed amplifier, the Raman amplification peaks (1510 and 1595 nm) are chosen to be far from the erbium amplification peak (1530–1570 nm) in order to avoid the overlapping and the saturation in the first...
Optics Communications, 2019
In this paper, we propose and experimentally demonstrate quadruple Brillouin-shift wavelength spa... more In this paper, we propose and experimentally demonstrate quadruple Brillouin-shift wavelength spacing (0.33 nm, 40 GHz) utilizing multiwavelength Brillouin-Erbium fiber laser (MBEFL) cavity. High Brillouin pump (BP) power, Pre-amplification technique, and capturing the residual pump power using wave selective coupler (WSC) are used to enhance laser comb tunability. The proposed structure has a tuning range of 60 nm (1530 nm-1590 nm) in the absence of self lasing cavity modes. Four stable Brillouin Stokes with high output power are achieved at 20mW and 225mW of BP and 1480 nm pump power respectively. In addition, multioutput ports with quadruple channel spacing is presented. This wide channel spacing make the proposed structure has strong potential to be used in dense wavelength division multiplexing (DWDM) communication systems.
Optical and Quantum Electronics
A Widely flatness gainbandwidth with double pass parallel hybrid fiber amplifier is experimentall... more A Widely flatness gainbandwidth with double pass parallel hybrid fiber amplifier is experimentally demonstrated in this study. The proposed design combines serial erbium-Raman fiber amplifier in one branch and Raman fiber amplifier in the second branch. Multiple Raman pump units with a maximum power of 800 mW (250 mW of 1410 nm, 225 mW of 1480 nm, and 325 mW of 1495 nm) are utilized. Pump recycling technique is applied to achieve acceptable pumping efficiency. A maximum flatness gain bandwidth of 80 nm (1525-1605 nm) and average gain level of 22.5 dB are obtained at a small input signal power of-25 dBm and optimum pump power values. By comparison, a wider flatness gain of 90 nm (1520-1610 nm) and average gain level of 11.5 dB are achieved at a large input signal power of-5 dBm.
2018 26th Signal Processing and Communications Applications Conference (SIU), 2018
In railways, to prevent the service failure and provide quality-safe journey, track and train saf... more In railways, to prevent the service failure and provide quality-safe journey, track and train safety has an important role. Specially broken and buckled rails, deterioration of wheels and failures in structural integrity of trains effects safety, causes big accidents and damages. Accordingly, by point detection of rail impairments and health monitoring, speed and location detection of trains are important issues. Fiber optic sensor systems supplies relevant costs to follow up the situations of these components. In this study, an fiber Bragg grating based strain sensor for railway safety is designed and experimentally performed.
World Academy of Science, Engineering and Technology, International Journal of Electrical, Computer, Energetic, Electronic and Communication Engineering, 2015
In this study, Brillouin Gain Spectrum (BGS) is experimentally analyzed in the Brillouin Optical ... more In this study, Brillouin Gain Spectrum (BGS) is experimentally analyzed in the Brillouin Optical Time Domain Reflectometry (BOTDR) and Brillouin Optical Time Domain Analyzer (BOTDA). For this purpose, the signal level of the microwave generator is varied and the effects of BGS are investigated. In the setups, 20 km conventional single mode fiber is used to both setups and laser wavelengths are selected around 1550 nm. To achieve best results, it can be used between 5 dBm to 15 dBm signal level of microwave generator for BOTDA and BOTDR setups. Keywords—Microwave signal level, Brillouin gain spectrum, BOTDA, BOTDR.
2017 4th International Conference on Electrical and Electronics Engineering, ICEEE 2017
In this study, the effects of erbium-doped fiber amplifier (EDFA) on Brillouin and Rayleigh power... more In this study, the effects of erbium-doped fiber amplifier (EDFA) on Brillouin and Rayleigh power spectrums are observed. For this analysis, Brillouin Optical Time Domain Analysis (BOTDA) configuration is used with an 18 km single mode fiber cable as the fiber under test (FUT) and 1550 nm band is utilized for the incident wave and EDFA. The scattered back wave is observed with both an RF spectrum analyzer and a high-resolution optical spectrum analyzer. The optical power level of Rayleigh backscattering did not change with respect to EDFA power; however, the SBS power level steadily increased. Compared to Rayleigh power, SBS becomes significant around and after the EDFA laser current of 270 mA.
Optik
Abstract In communication systems, it is important to transmit very large amounts of data over lo... more Abstract In communication systems, it is important to transmit very large amounts of data over long distances through fast and safe means. Optical amplifiers have been used to increase communication distance of fiber optic lines. One of the most used optical amplifiers is Erbium-doped fiber amplifiers (EDFA) which have high gain, low noise figure, high bandwidth, and simple compact structures. During the design processes of an EDFA, the fiber type, length and temperature dependent parameters become the main factors to consider. In this study, EDFAs designed using I6, I25, M5 and M12 EDFs produced by FiberCore Company are characterized for varying temperatures. Firstly, required EDF lengths for optimum flat gain spectrum in C band are calculated using OptiAmplifier 4.0 software. Then, the effects of temperature on the gain spectrum of EDFAs are analyzed. Finally, the temperature independent quiescent regions are determined for all these EDFs.
Optics Communications
Abstract In a weakly marine turbulent medium, formulation of the on-axis scintillation index of a... more Abstract In a weakly marine turbulent medium, formulation of the on-axis scintillation index of a flat topped Gaussian beam is derived by using the Rytov method and the intensity has log-normal distribution expressed. The scintillation index and average bit error rate with respect to changes in propagation distance, wavelength, beam size, and average signal to noise ratio are exhibited. Our results indicated that small advantage can be achieved in weak atmospheric marine when focal length equals to propagation distance and when the order of flatness is small value.
2016 24th Signal Processing and Communication Application Conference (SIU), 2016
In this study, a Fiber Bragg Grating (FBG) based temperature sensor is designed. Simulation is co... more In this study, a Fiber Bragg Grating (FBG) based temperature sensor is designed. Simulation is conducted to observe FBG's response to the temperature change. The temperature incident on the FBG is gradually changed from 0°C to 60°C in 10°C steps and the frequency shifts in both RF and optical spectrum are observed.
2016 24th Signal Processing and Communication Application Conference (SIU), 2016
Fiber optic cables are widely used in sensor applications of temperature, strain and pressure. Th... more Fiber optic cables are widely used in sensor applications of temperature, strain and pressure. The long sensing range, minimal power consumption and other advantages of classic fiber cables make these sensor systems very appealing. In this paper, the application of single mode fiber as temperature sensor and its effect are studied.
2012 20th Signal Processing and Communications Applications Conference (SIU), 2012
In this study, fiber lengths of each stage of the three stages L band erbium doped fiber amplifie... more In this study, fiber lengths of each stage of the three stages L band erbium doped fiber amplifier (L-EDFA) and the pump laser power are optimized to achieve the maximum gain, the minimum noise figure and the minimum gain ripple. It is obtained on an average 34.7–37.1 dB gain, 6.28–6.0 dB noise figure, and 2.13–2.28 dB gain ripple along all
JOURNAL OF POLYTECHNIC, 2005
Bu çal Cmada, bina içi kablosuz yerel alan a,lar ndaki optik güç da, l m problemi incelenmiCtir. ... more Bu çal Cmada, bina içi kablosuz yerel alan a,lar ndaki optik güç da, l m problemi incelenmiCtir. Bir ofis veya ma,aza kat ndaki k z lötesi C k kaynaklar taraf ndan üretilen optik gücün da, l m incelenmiCtir. IC k kaynaklar n n yerleCim deseni, vericilerin say s gibi faktörlerin güç da, l m n n uniformlu,una olan etkileri araCt r lm Ct r. Oda büyüklü,ünün bir fonksiyonu olarak vericilerin say s ve konumlar hesaplanm Ct r. Bu amaçla algoritmik bir bilgisayar program haz rlanm C ve simülasyon gerçekleCtirilmiCtir. Simülasyon yaklaC m , iç mekan güç da, l m n n uniformlu,u için gerekli Cartlar n elde edilmesinde kullan lm Ct r. Sonuçta en iyi güç da, l m n n, vericileri oda tavan na kare zgara Ceklinde yerleCtirmekle elde edilebilece,i görülmüCtür.
2014 22nd Signal Processing and Communications Applications Conference (SIU), 2014
ABSTRACT Fiber optic sensor technology based on Brillouin scattering is rapidly spreading due to ... more ABSTRACT Fiber optic sensor technology based on Brillouin scattering is rapidly spreading due to quantities is great precision measured such as temperature, strain and vibration in the long haul distributed sensing. In this study Brillouin scattering has been analyzed in the single mode fiber. An experimental setup has been done using OptiSystem 12.0, and Brillouin scattering monitored graphically in the 50 km optical fiber cable.
Optik - International Journal for Light and Electron Optics, 2012
In this study, a single modelling approach based on fuzzy logic (FL) device is designed for a qua... more In this study, a single modelling approach based on fuzzy logic (FL) device is designed for a quantumwell (QW) laser diode to obtain the characteristic quantities and their dependences on wavelength and injection currents. The fuzzy rules are compiled using the input variables which are namely the wavelength and the injection currents, while the output parameters are the modal gain difference, the effective refractive index difference and alpha (˛) parameter (linewidth enhancement factor). The suggested approach provides fast and reliable predictions which can prevent the engineers from rigorous experiments/calculations. The FL device provides the predictions of modal gain difference, effective refractive index difference and alpha parameter against the wavelength and the injection currents within the accuracy level of 90-99.9%.
Signal Processing and …, 2011
2013 8th International Conference on Electrical and Electronics Engineering (ELECO), 2013
Intelligent Automation & Soft Computing, 2009
ABSTRACT—3D Virtual Reality (VR) platforms developed on computers can prevent users from possible... more ABSTRACT—3D Virtual Reality (VR) platforms developed on computers can prevent users from possible risks of real physical environments. We are developing hardware and software based training system, in which training of driver candidates is possible. As a part of the ...
… Conference, 2008. SIU 2008. IEEE 16th, 2008
... Parametreler Değerler Kesim Dalga boyu 891 nm 1300 nm kaybı 1,45 dB/km İyon ömrü 10 ms Öz yar... more ... Parametreler Değerler Kesim Dalga boyu 891 nm 1300 nm kaybı 1,45 dB/km İyon ömrü 10 ms Öz yarıçapı 1,77 µm Erbiyum ... Deney düzeneğinde optik spektrum analizörü (OSA) olarak Anritsu MS9710B ve ayarlanabilir lazer kaynağı (TLS) olarak Santec TLS210V kullanılmıştır. ...
Materials & Design, Jan 1, 2009
GU Journal of Science, Jan 1, 2006
Microwave and Optical Technology Letters, 2021
In this article, we experimentally propose an efficient wide flat gain bandwidth with a parallel ... more In this article, we experimentally propose an efficient wide flat gain bandwidth with a parallel hybrid fiber amplifier. The setup includes parallel amplifier branches. In the first branch, serial erbium‐doped and Raman fiber amplifiers are used. In the second branch, only a Raman fiber amplifier is used. Three Raman pump power units (i.e., 1410, 1480, and 1495 nm) are used to achieve Raman gain at different optical communication bands. At optimum pump powers and at a small‐signal power of −30 dBm, an average gain of 18.5 dB with a maximum gain variation of 3 dB and a gain flatness bandwidth of 83 nm, that is, from 1527 to 1610 nm, is achieved. This gain flatness is expanded to 92 nm (1525–1617 nm) at a large input signal power of −5 dBm with an average gain level of 13 dB. In our proposed amplifier, the Raman amplification peaks (1510 and 1595 nm) are chosen to be far from the erbium amplification peak (1530–1570 nm) in order to avoid the overlapping and the saturation in the first...
Optics Communications, 2019
In this paper, we propose and experimentally demonstrate quadruple Brillouin-shift wavelength spa... more In this paper, we propose and experimentally demonstrate quadruple Brillouin-shift wavelength spacing (0.33 nm, 40 GHz) utilizing multiwavelength Brillouin-Erbium fiber laser (MBEFL) cavity. High Brillouin pump (BP) power, Pre-amplification technique, and capturing the residual pump power using wave selective coupler (WSC) are used to enhance laser comb tunability. The proposed structure has a tuning range of 60 nm (1530 nm-1590 nm) in the absence of self lasing cavity modes. Four stable Brillouin Stokes with high output power are achieved at 20mW and 225mW of BP and 1480 nm pump power respectively. In addition, multioutput ports with quadruple channel spacing is presented. This wide channel spacing make the proposed structure has strong potential to be used in dense wavelength division multiplexing (DWDM) communication systems.
Optical and Quantum Electronics
A Widely flatness gainbandwidth with double pass parallel hybrid fiber amplifier is experimentall... more A Widely flatness gainbandwidth with double pass parallel hybrid fiber amplifier is experimentally demonstrated in this study. The proposed design combines serial erbium-Raman fiber amplifier in one branch and Raman fiber amplifier in the second branch. Multiple Raman pump units with a maximum power of 800 mW (250 mW of 1410 nm, 225 mW of 1480 nm, and 325 mW of 1495 nm) are utilized. Pump recycling technique is applied to achieve acceptable pumping efficiency. A maximum flatness gain bandwidth of 80 nm (1525-1605 nm) and average gain level of 22.5 dB are obtained at a small input signal power of-25 dBm and optimum pump power values. By comparison, a wider flatness gain of 90 nm (1520-1610 nm) and average gain level of 11.5 dB are achieved at a large input signal power of-5 dBm.
2018 26th Signal Processing and Communications Applications Conference (SIU), 2018
In railways, to prevent the service failure and provide quality-safe journey, track and train saf... more In railways, to prevent the service failure and provide quality-safe journey, track and train safety has an important role. Specially broken and buckled rails, deterioration of wheels and failures in structural integrity of trains effects safety, causes big accidents and damages. Accordingly, by point detection of rail impairments and health monitoring, speed and location detection of trains are important issues. Fiber optic sensor systems supplies relevant costs to follow up the situations of these components. In this study, an fiber Bragg grating based strain sensor for railway safety is designed and experimentally performed.
World Academy of Science, Engineering and Technology, International Journal of Electrical, Computer, Energetic, Electronic and Communication Engineering, 2015
In this study, Brillouin Gain Spectrum (BGS) is experimentally analyzed in the Brillouin Optical ... more In this study, Brillouin Gain Spectrum (BGS) is experimentally analyzed in the Brillouin Optical Time Domain Reflectometry (BOTDR) and Brillouin Optical Time Domain Analyzer (BOTDA). For this purpose, the signal level of the microwave generator is varied and the effects of BGS are investigated. In the setups, 20 km conventional single mode fiber is used to both setups and laser wavelengths are selected around 1550 nm. To achieve best results, it can be used between 5 dBm to 15 dBm signal level of microwave generator for BOTDA and BOTDR setups. Keywords—Microwave signal level, Brillouin gain spectrum, BOTDA, BOTDR.
2017 4th International Conference on Electrical and Electronics Engineering, ICEEE 2017
In this study, the effects of erbium-doped fiber amplifier (EDFA) on Brillouin and Rayleigh power... more In this study, the effects of erbium-doped fiber amplifier (EDFA) on Brillouin and Rayleigh power spectrums are observed. For this analysis, Brillouin Optical Time Domain Analysis (BOTDA) configuration is used with an 18 km single mode fiber cable as the fiber under test (FUT) and 1550 nm band is utilized for the incident wave and EDFA. The scattered back wave is observed with both an RF spectrum analyzer and a high-resolution optical spectrum analyzer. The optical power level of Rayleigh backscattering did not change with respect to EDFA power; however, the SBS power level steadily increased. Compared to Rayleigh power, SBS becomes significant around and after the EDFA laser current of 270 mA.
Optik
Abstract In communication systems, it is important to transmit very large amounts of data over lo... more Abstract In communication systems, it is important to transmit very large amounts of data over long distances through fast and safe means. Optical amplifiers have been used to increase communication distance of fiber optic lines. One of the most used optical amplifiers is Erbium-doped fiber amplifiers (EDFA) which have high gain, low noise figure, high bandwidth, and simple compact structures. During the design processes of an EDFA, the fiber type, length and temperature dependent parameters become the main factors to consider. In this study, EDFAs designed using I6, I25, M5 and M12 EDFs produced by FiberCore Company are characterized for varying temperatures. Firstly, required EDF lengths for optimum flat gain spectrum in C band are calculated using OptiAmplifier 4.0 software. Then, the effects of temperature on the gain spectrum of EDFAs are analyzed. Finally, the temperature independent quiescent regions are determined for all these EDFs.
Optics Communications
Abstract In a weakly marine turbulent medium, formulation of the on-axis scintillation index of a... more Abstract In a weakly marine turbulent medium, formulation of the on-axis scintillation index of a flat topped Gaussian beam is derived by using the Rytov method and the intensity has log-normal distribution expressed. The scintillation index and average bit error rate with respect to changes in propagation distance, wavelength, beam size, and average signal to noise ratio are exhibited. Our results indicated that small advantage can be achieved in weak atmospheric marine when focal length equals to propagation distance and when the order of flatness is small value.
2016 24th Signal Processing and Communication Application Conference (SIU), 2016
In this study, a Fiber Bragg Grating (FBG) based temperature sensor is designed. Simulation is co... more In this study, a Fiber Bragg Grating (FBG) based temperature sensor is designed. Simulation is conducted to observe FBG's response to the temperature change. The temperature incident on the FBG is gradually changed from 0°C to 60°C in 10°C steps and the frequency shifts in both RF and optical spectrum are observed.
2016 24th Signal Processing and Communication Application Conference (SIU), 2016
Fiber optic cables are widely used in sensor applications of temperature, strain and pressure. Th... more Fiber optic cables are widely used in sensor applications of temperature, strain and pressure. The long sensing range, minimal power consumption and other advantages of classic fiber cables make these sensor systems very appealing. In this paper, the application of single mode fiber as temperature sensor and its effect are studied.
2012 20th Signal Processing and Communications Applications Conference (SIU), 2012
In this study, fiber lengths of each stage of the three stages L band erbium doped fiber amplifie... more In this study, fiber lengths of each stage of the three stages L band erbium doped fiber amplifier (L-EDFA) and the pump laser power are optimized to achieve the maximum gain, the minimum noise figure and the minimum gain ripple. It is obtained on an average 34.7–37.1 dB gain, 6.28–6.0 dB noise figure, and 2.13–2.28 dB gain ripple along all
JOURNAL OF POLYTECHNIC, 2005
Bu çal Cmada, bina içi kablosuz yerel alan a,lar ndaki optik güç da, l m problemi incelenmiCtir. ... more Bu çal Cmada, bina içi kablosuz yerel alan a,lar ndaki optik güç da, l m problemi incelenmiCtir. Bir ofis veya ma,aza kat ndaki k z lötesi C k kaynaklar taraf ndan üretilen optik gücün da, l m incelenmiCtir. IC k kaynaklar n n yerleCim deseni, vericilerin say s gibi faktörlerin güç da, l m n n uniformlu,una olan etkileri araCt r lm Ct r. Oda büyüklü,ünün bir fonksiyonu olarak vericilerin say s ve konumlar hesaplanm Ct r. Bu amaçla algoritmik bir bilgisayar program haz rlanm C ve simülasyon gerçekleCtirilmiCtir. Simülasyon yaklaC m , iç mekan güç da, l m n n uniformlu,u için gerekli Cartlar n elde edilmesinde kullan lm Ct r. Sonuçta en iyi güç da, l m n n, vericileri oda tavan na kare zgara Ceklinde yerleCtirmekle elde edilebilece,i görülmüCtür.
2014 22nd Signal Processing and Communications Applications Conference (SIU), 2014
ABSTRACT Fiber optic sensor technology based on Brillouin scattering is rapidly spreading due to ... more ABSTRACT Fiber optic sensor technology based on Brillouin scattering is rapidly spreading due to quantities is great precision measured such as temperature, strain and vibration in the long haul distributed sensing. In this study Brillouin scattering has been analyzed in the single mode fiber. An experimental setup has been done using OptiSystem 12.0, and Brillouin scattering monitored graphically in the 50 km optical fiber cable.
Optik - International Journal for Light and Electron Optics, 2012
In this study, a single modelling approach based on fuzzy logic (FL) device is designed for a qua... more In this study, a single modelling approach based on fuzzy logic (FL) device is designed for a quantumwell (QW) laser diode to obtain the characteristic quantities and their dependences on wavelength and injection currents. The fuzzy rules are compiled using the input variables which are namely the wavelength and the injection currents, while the output parameters are the modal gain difference, the effective refractive index difference and alpha (˛) parameter (linewidth enhancement factor). The suggested approach provides fast and reliable predictions which can prevent the engineers from rigorous experiments/calculations. The FL device provides the predictions of modal gain difference, effective refractive index difference and alpha parameter against the wavelength and the injection currents within the accuracy level of 90-99.9%.
Signal Processing and …, 2011
2013 8th International Conference on Electrical and Electronics Engineering (ELECO), 2013
Intelligent Automation & Soft Computing, 2009
ABSTRACT—3D Virtual Reality (VR) platforms developed on computers can prevent users from possible... more ABSTRACT—3D Virtual Reality (VR) platforms developed on computers can prevent users from possible risks of real physical environments. We are developing hardware and software based training system, in which training of driver candidates is possible. As a part of the ...
… Conference, 2008. SIU 2008. IEEE 16th, 2008
... Parametreler Değerler Kesim Dalga boyu 891 nm 1300 nm kaybı 1,45 dB/km İyon ömrü 10 ms Öz yar... more ... Parametreler Değerler Kesim Dalga boyu 891 nm 1300 nm kaybı 1,45 dB/km İyon ömrü 10 ms Öz yarıçapı 1,77 µm Erbiyum ... Deney düzeneğinde optik spektrum analizörü (OSA) olarak Anritsu MS9710B ve ayarlanabilir lazer kaynağı (TLS) olarak Santec TLS210V kullanılmıştır. ...
Materials & Design, Jan 1, 2009
GU Journal of Science, Jan 1, 2006