OPTOELECTRONICS AND ADVANCED MATERIALS – RAPID COMMUNICATIONS Vol. 9, No. 5-6, May – June 2015, p. 575 - 581 Comparative study of performance of EDFA/Raman hybrid optical amplifier with Raman only amplifier and EDFA only amplifier O. MAHRAN a,b,* , AHMED E. EL-SAMAHY a , MOUSTAFA H. ALY c , MOURAD ABD EL HAI a a Faculty of science, physics department, Alexandria University, Mohram Beh 21511, Alexandria, Egypt b Faculty of science, physics department, Al Jouf University, Al Jouf, Saudi Arabia c College of Engineering and Technology, Arab Academy for Science, Technology and Maritime Transport Alexandria, Egypt In this paper, comparative study of the gain and noise figure for EDFA/Raman hybrid amplifier, EDFA and Raman amplifier was done. In addition, the optical signal to noise ratio (OSNR) is calculated as a function of signal wavelength. The higher gain was 41.1 dB for EDFA/Raman hybrid amplifier at -30 dBm input signal power, 100 mW of both EDFA and Raman pump power and signal wavelength of 1530 nm and the lower noise figure was 3.8 dB for EDFA only at -30 dBm input signal power, 100 mW of EDFA pump power and signal wavelength of 1530nm. The lower values of OSNR obtained for Raman amplifier only at signal wavelength 1530 – 1600 nm with -30 dBm input signal power and 100 mW Raman pump power. The flatness of the gain profile of EDFA/Raman hybrid amplifier is higher than of both EDFA only and Raman only. (Received April 3, 2015; accepted May 7, 2015) Keywords: Raman effect- EDFA – Pump power – Amplifier length – Hybrid optical amplifier 1. Introduction Extremely high signal gains and low noise figures can be achieved in EDFAs with modest pump powers. (For instance, in an EDFA a signal gain of a few dB per mW of pump power is obtainable, whereas only 0.06 dB of gain per mW of pump power in a Raman amplifier is achievable in typical optical transmission fibers at present) [1]. Over the last several years, we have witnessed a tremendous rebirth of the interest in Raman amplification in optical fibers. Practical, efficient, high-power pump sources have diminished the disadvantage of the relatively poor efficiency of the Raman process compared to the erbium amplification process, and Raman amplifiers do offer several very attractive advantages over EDFAs [2]. Because the important features of EDFAs, many researches and developments were done to improve the characteristics of such amplifier and the other optical amplifiers, and in the last few years, the amplification of optical signals by stimulated Raman scattering in Raman fiber were done for future telecommunications systems [3]. The use of distributed Raman amplification in transmission fibers can provide improved noise figure, signal power gain and optical signal to noise ratio (OSNR). EDFA/Raman with hybrid configuration has been extensively studied showing low noise figure and high gain for transmission systems compared to conventional EDFA [4]. Lee et al. work on experimental study of performance comparison of three different schemes of single pump dispersion-compensating fiber (DCF) – based Raman/EDFA hybrid amplifiers [5], also M. H. Abu Bakar et al. work on L- band remote EDFA/Raman hybrid amplifiers experimentally and they choose the L – band for flat gain [6]. Furthermore, Simranjit Singh et al., demonstrate a paper for investigation comparison of EDFA, Raman and semiconductor optical amplifiers (SOA) individually and the performance has been compared on the basis of transmission distance and dispersion with and without nonlinearities [7]. In this paper, we make a comparative study of the three types of optical amplifier, EDFA/Raman hybrid, Raman only and EDFA only amplifier. In this comparison, the gain and noise figure profiles (plotted as a function of signal wavelength) are calculated for different values of input signal power, EDFA pump power and RA pump powers for the three types of amplifiers, EDFA/Raman hybrid, Raman only and EDFA only amplifier. 2. Model of calculations 2.1 Raman amplification When an input signal is introduced to an optical fiber with strong pump, it will be amplified due to the Raman interaction between the pump and signal, so the signal and pump power can be described by the following equations [8]    =         −    (1)