Automatic Gain Control of Erbium-Doped Fiber Amplifiers for WDM Transmission Systems

Katsuhiro SHIMIZU
Katsumi TAKANO
Tadayoshi KITAYAMA
Katsuyoshi ITO

IEICE TRANSACTIONS on Communications   Vol.E80-B       pp.1311-1320
Publication Date: 1997/09/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Category: Optical Communication
optical communication,  wavelength-division,  multiplexing,  erbium-doped fiber amplifier,  automatic gain control,  transient gain saturation,  

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Optical transmission systems with large capacity employing wavelength-division multiplexing (WDM) techniques are now widely under development. Optical amplifiers, especially Erbium-Doped Fiber Amplifiers (EDFA's), are vital components for such transmission systems. Optical amplifiers in WDM systems are employed as common amplifiers for all WDM'ed optical carriers, therefore, change in power of a specific carrier gives rise to gain fluctuation of the remaining carriers. In this paper, we discuss about automatic gain control (AGC) of EDFA for WDM'ed optical carriers under transient gain saturation. Two methods have been reported to perform AGC, i.e., pump feedback control method and compensation light feedback control method. Theory and experimental results have been already reported on pump feedback control method. Here, theory has been generalized to be applicable for compensation light feedback method including schematics with amplified spontaneous emission (ASE) as a probe light to measure the gain of EDFA. Experimental results have confirmed the analysis. Good performance has been obtained for both methods with simple electronic circuits and ASE has been found to work as an excellent probe light source.