Superior Noise Performance and Wide Dynamic Range Erbium Doped Fiber Amplifiers Employing Variable Attenuation Slope Compensator

Haruo NAKAJI  Motoki KAKUI  Hitoshi HATAYAMA  Chisai HIROSE  Hiroyuki KURATA  Masayuki NISHIMURA  

Publication
IEICE TRANSACTIONS on Communications   Vol.E84-B   No.5   pp.1224-1230
Publication Date: 2001/05/01
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Joint Special Issue on Recent Progress in Optoelectronics and Communications)
Category: Optical Fibers and Cables
Keyword: 
optical amplifier,  wavelength division multiplexing system,  automatic level control,  variable attenuation slope compensator,  

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Summary: 
In order to realize automatic-level-controlled (ALC) erbium doped fiber amplifiers (EDFAs) with both wide dynamic range and good noise performance, we propose EDFAs employing the automatic power control (APC) scheme and a variable attenuation slope compensator (VASC). The VASC consists of two asymmetrical Mach-Zehnder interferometers (MZIs) concatenated in series and thermo optic (TO) heaters are attached to the arms of each MZIs. By adjusting the electric power supplied to the TO heaters, an almost linear attenuation slope can be varied by plus minus 5 dB or more over the operational wavelength band of 30 nm. The EDFA employing the APC scheme and the VASC has exhibited a dynamic range as large as 20 dB with the output power variation as small as 0.7 dB, which is as good as that of the EDFA employing the APC scheme and a variable optical attenuator (VOA). The noise figure (NF) of the EDFA employing the VASC was degraded about 4.1 dB with increasing the input power by 20 dB, while it was degraded about 7.3 dB with increasing the input power by only 15 dB in the EDFA employing the VOA. The EDFA employing the VASC can realize the ALC operation over a wider dynamic range with reduced noise figure degradation. In the EDFA employing the VASC, the power excursion was suppressed to less than 1.1 dB, when the input signal level was changed between -23 dBm/ch and -18 dBm/ch with the rise/fall time of 8 ms.