EDFA gain flattening using periodic tapered fibre filters

Cullen, Thomas J.; Jolley, N.E.; Davis, F.; Mun, J.

doi:10.1364/oaa.1997.faw13

Cited by 6 publications

(1 citation statement)

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“…This nonuniform spectral shape results in a serious reduction of gain bandwidth when EDFAs are cascaded in transmission links [2], [3]. To achieve flat gain in the C band, external filtering fiber devices, such as fiber gratings [4], [5], acousto-optic tunable filters (AOTFs) [6], [7], and tapered fiber filters [8], [9] have been developed. Even though these devices showed excellent performance in gain-flattening, elaborate control of operating conditions, such as temperature and strain with special packaging, are required.…”

Section: Introductionmentioning

confidence: 99%

Inherent enhancement of gain flatness and achievement of broad gain bandwidth in erbium-doped silica fiber amplifiers

Ryu

Shin

et al. 2002

IEEE J. Quantum Electron.

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We report new methods to inherently increase the flatness and bandwidth of erbium-doped silica fiber amplifiers from three perspectives: fiber design, pump-signal WDM coupler optimization, and amplifier structure. First, to achieve inherent control of the gain spectrum, a new type of composite fiber structure with an Er-doped core and a Sm-doped cladding ring is proposed and experimentally demonstrated. Interaction of the optical field with the Sm-doped cladding to produce evanescent wave filtering is modeled, which provides an in-line control of gain fluctuation in the erbium-doped fiber amplifier (EDFA) C band, 1530-1560 nm. Second, the effect of the spectral characteristics of WDM couplers over the L band of an EDFA is explored. A fused taper fiber coupler for a 1480-nm pump is optimized for signals in the wavelength range of 1570-1610 nm by measuring the small-signal gain, gain tilt, and noise figure in an L-band EDFA. Finally, a new all-fiber structure for a wide-band EDFA, where the L and C bands were coupled serially, is demonstrated with optimized pump-signal couplers. Further optimization of the new composite fiber structure and the transient effects in the serially coupled EDFAs are also discussed. Index Terms-Erbium-doped fiber (EDF), erbium-doped fiber amplifier (EDFA), fused taper fiber coupler, gain flattening, WDM coupler, wide-band optical amplifier.

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