Ahmet Altuncu - Academia.edu (original) (raw)

Papers by Ahmet Altuncu

DergiPark (Istanbul University), Aug 31, 2022

IEEE Photonics Technology Letters, Jul 1, 2005

Journal of Modern Optics, Apr 12, 2021

In this study, the gain clamping performance of Hafnia-bismuth-erbium co-doped fibre amplifier (H... more In this study, the gain clamping performance of Hafnia-bismuth-erbium co-doped fibre amplifier (HB-EDFA) using a lasing controlled structure with fibre Bragg grating (FBG) pair is presented. First, the gain and noise figure (NF) characteristics of a bidirectionally pumped HB-EDFA with very short lengths of heavily doped fibre are presented regarding its critical design parameters such as HB-EDF length, pump power, input signal power and signal wavelength. Then, the gain clamping performance of a bidirectionally pumped HB-EDFA having a C-band FBG pair with Bragg wavelengths of 1534 and 1542 nm is experimentally analysed. A good gain clamping capability was obtained using the proposed bidirectionally HB-EDFA design which has resulted in a dynamic signal input power range of 25 dB at 16 dB signal gain for 1.6 m HB-EDF length, and a wider dynamic signal input power range of 30 dB at 10 dB signal gain for 1.1 m HB-EDF length.

Journal of Lightwave Technology, Jul 1, 2008

Journal of electrical engineering, Sep 28, 2016

... Acknowledgments: The authors wish to acknowledge JG Ellison and B. Diamond from University of... more ... Acknowledgments: The authors wish to acknowledge JG Ellison and B. Diamond from University of Essex, Colchester, UK for helping with ... Polarimetric Optical Time Domain Reflectometer with one meter Spatial Resolution, OFC'97, WL24, Dallas, 199'7. RA Sammut, CD Hussey ...

Results in optics, Aug 1, 2022

Optoelectronics Letters, Oct 1, 2021

In this study, the performance of a forward pumped erbium doped fiber amplifier (EDFA) which is s... more In this study, the performance of a forward pumped erbium doped fiber amplifier (EDFA) which is suitable to be used as a preamplifer in fiber optical communication systems is analyzed experimentally regarding the dependece of its performance on exact pumping wavelength at 980 nm region. The gain and noise figure (NF) characteristics of an EDF preamplifier is obtained for the pump laser wavelengths of 974 nm and 976 nm having different absorption cross sections. It has been shown that the experimental gain and NF characteristics are consistent with the absorption spectrum of the erbium doped fiber used. Furthermore, we report 1–2 dB variation in gain and NF performance of EDFA in response to a nanometer change at pump wavelength. As a result, in designing a forward pumped EDFA with a high gain and a low NF performance, the exact wavelength of the pump laser used should be very closed to the peak absorption wavelength of EDF.

In long-haul and high-bit-rate optical fiber transmission systems Polarization Mode Dispersion (P... more In long-haul and high-bit-rate optical fiber transmission systems Polarization Mode Dispersion (PMD) is one of the main reasons for pulse broadening. In order to reduce PMD-based problems, current studies rely on novel PMD compensators and low-PMD fiber productions. In this paper, after describing theoretical information about PMD and optical fiber spinning process, different spin profiles are examined. Comparative analysis of spin profiles is made and spin parameters giving successful results for low-PMD fibers are obtained for each spin profile. Simulation results show that for fixed spin period of 1 m 2.76 turns/m and 5.64 turns/m are proper spin amplitude values for sinusoidal and amplitude modulated (AM) spin profiles, respectively, while 3.40 turns/m and 3.75 turns/m are recommended spin amplitudes for triangular and trapezoidal spin profiles, respectively. Using these parameters, related spin profiles give better differential group delay (DGD) reduction results individually.

Electronics Letters, 1997

A compact tunable C+L band erbium-doped fiber ring laser (EDFRL) with micro-electro-mechanical sy... more A compact tunable C+L band erbium-doped fiber ring laser (EDFRL) with micro-electro-mechanical system (MEMS) based optical tunable bandpass filter was developed. The effects of erbium-doped fiber (EDF) length, output coupling ratio and pump power levels on its spectral characteristics have been analysed and optimized experimentally. With the parameters of EDF length of 6 m, output coupler ratio of 90:10 and both pump powers of 120 mW, a moderate output power level (sim+4.5(\sim +4.5(sim+4.5 dBm) and a wide wavelength tuning range (sim80(\sim 80(sim80 nm) covering both C- and L- bands have been achieved.

InTech eBooks, Sep 21, 2016

Optics and Laser Technology, Apr 1, 2020

$Research paper thumbnail of A Universal and Stable All-Fiber Refractive Index Sensor System$

IEEE Photonics Technology Letters, Jan 15, 2016

In this letter, a universal, simple, and stable all-fiber sensor system is proposed to measure th... more In this letter, a universal, simple, and stable all-fiber sensor system is proposed to measure the refractive index (RI) of liquids. The basic principle of the technique is based on the relative measurement of the Fresnel reflection from sensor probes. A quadruple of time-division multiplexed Fresnel reflected pulses are obtained from a single nanosecond input pulse owing to the latencies in fibers with different lengths. The measured RIs for the different liquids show that the proposed all-fiber RI sensor system enables linear and repeatable measurements. The performance of the system is compared with the previously published studies, and good agreement is observed, showing the accuracy of the measurements. The standard deviations of the measured RIs are obtained in a short-term measurement as 2.8 × 10-6 for distilled water, and in a long-term measurement as 2.99×10-5 for methanol, showing the high repeatability of the measurements.

Optics Communications, Mar 1, 2017