Suppression of the Cross-Gain Modulation in Remotely-Pumped EDF/DRA Hybrid Inline Amplifier Systems with Online OTDR for Gain Monitoring

Kenji SATO

IEICE TRANSACTIONS on Communications   Vol.E88-B    No.5    pp.1986-1993
Publication Date: 2005/05/01
Online ISSN: 
DOI: 10.1093/ietcom/e88-b.5.1986
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Joint Special Section on Recent Progress in Optoelectronics and Communications)
Category: Transmission Systems and Technologies
OTDR,  remote pumping,  distributed Raman amplifier,  cross gain modulation,  

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Novel gain monitoring scheme in Remotely-Pumped EDF/DRA hybrid inline amplifier is proposed using Optical Time Domain Reflectometer (OTDR). Signal degradation due to cross gain modulation (XGM) caused by an OTDR pulse in the distributed Raman amplifier (DRA) section and remotely-pumped EDF (RP-EDF) unit is analyzed theoretically. The required conditions for suppressing of XGM in the DRA section are derived. We propose the directional bypass configuration to realize OTDR measurement without XGM in the EDF unit. Transmission experiments using the RP-EDF/DRA hybrid inline amplifier demonstrate the absence of transmission impairement induced by OTDR. An analysis of the OTDR trace for each gain medium is also discussed. The theoretical analysis agrees well with the experimental result.