Gain and noise characteristics of all-optical gain-clamped Fabry-Perot lasing erbium-doped fiber amplifier using fiber Bragg reflectors

In this paper, gain and noise characteristics of gain-clamped Fabry-Perot lasing erbium-doped fiber amplifier(EDFA) is investigated in detail when reflective wavelength and reflectivity of the fiber Bragg gratings (FBG) areselected different values. The relationships between gain and noise performance of the gain-clamped EDFA and theselection ofFBG parameters such as reflectivity and reflective wavelength are investigated and analyzed. It is found vianumerical simulation that the selection of FBG parameters has important influence on the performance of the EDFA.The results obtained in this paper can provide significant datum and reference for optimizing and improving the performance of all-optical gain-clamped EDFA. Key words: EJJFA; WDM; all-optical gain clamp; Fabry-Perot cavity 1. Introduction Gain-clamped fiber amplifier is indispensable to overcome the gain fluctuations as the requirements in applications of wavelength-division multiplexing communication system. Generally, there are two main methods torealize gain clamping ofEDFA: electrical gain control 41or all-optical gain control5'21. In the former method, drivingcurrent of pumping laser is modulated in real time according to the feedback signal ofthe output power change detectedby controlling circuit to maintain the constant power level. Its main drawback is that many additional electrical devicesare needed and output signals are obtained with high electrical delay. In the latter method, loop or linear lasing cavity isformed by optical components such as fiber grating, variable attenuators and circulators to constitute stable lasing inamplifier, by which the gain fluctuation of EDFA is under control. This scheme has advantages of real time gainclamped and all-optical integration. The gain clamp in an Erbium-doped fiber amplifier (EDFA) achieved by aFabry-Perot lasing with fiber Bragg reflectors has the advantages of having no additional signal loss, lower cost andsimpler configuration comparing with all-optical gain-clamped EDFA obtained by a fiber-ring lasing cavity. In thispaper, The relationships between gain and noise performance of the gain-clamped EDFA and the selection of FBGparameters such as reflectivity and reflective wavelength are investigated and analyzed in detail. It is found vianumerical simulation that the selection of FBG parameters has important influence on the performance of the EDFA.The results obtained in this paper can provide significant datum and reference for optimizing and improving the