The Design And Implementation Of Optical Power Control Mechanism On DWDM System

Services encapsulated into IP packets are spreading all over telecom field quickly when3G age comes. Constructions of metropolitan integrated transmission networks have been thefocus to all the telecom suppliers. While3G networks are taking IP program from top tobottom, the metropolitan integrated transmission network architecture of telecom suppliersare taking tremendous changes. Moreover, services are expected to be transmitted on thephotonic layer, which can make the network transmission of Ethernet services become morefeasible. Metropolitan integrated transmission networks based on traditional WDMtechnology are gradually developing towards the smart networks which can support moretransmission wavelengths, higher speed signal rate single wavelength and WDM networksinter-communication. DWDM systems are able to carry various traffic services with differentsignal rates, which really birng new challenges to DWDM system transmission performance.Erbium doped fiber amplifiers take advantage of their high price-performance ratio, acting asthe core modules of DWDM optical networks. EDFA’s characters make the ifnal decision ofthe whole transmission performance of DWDM networks. Traditional EDFAs usually havedifferent gain for various wavelengths in band, which has strongly restricted the transmissiondistance of DWDM system. Specially, DWDM system would get worse transmissionperformance under cascaded EDFAs condition.In this paper, a seiral of researches and analysis have been made on dynamic gainequalization of EDFA on oirginal system in order to verify the feasibility of the powerequalization by means of VOA tuning technology. According to the optical transmissionpower control requirements of the next generation intelligent metropolitan DWDMtransmission networks, the preemphasis technology combined with optical amplifier pumpcurrent tuning solution has been designed and implemented. The main design purpose is that optical transmission control algorithm, transmission information stamps mechanism and gainstep tuning algoirthm are used to take control of the total output optical power and gain tilt ofthe EDFA on the optical line in DWDM networks. Moreover, automatic power equalizationalgorithm would be taken to control the VOA ’values in order to realize the channels opticalpower equalization.The smart optical power equalization control mechanism has been accomplished viatheory analysis, system function implement and system veirfication tests. It makes theEDFA’s gai’n tilt of customers oirginal40-channel DWDM system get5dB flat atfer threefiber span transmission’. Moreover，all the in-service optical channels OSNR is no lower than26dB and their optical power tilt is controlled under2dB, which has got6dB flatter thanbefore.