Investigation on hybrid optical amplifiers and four wave mixing crosstalk reduction in dense wavelength division multiplexed dwdm network

Abstract

The tremendous growth in the number of internet users and therapid increase of multimedia services has led to the relentless demand fornetworks of higher capacities. One of the classic solutions for rising theinformation carrying capacity is the use of Wavelength DivisionMultiplexing (WDM). In WDM, independent electrical bit streams modulateoptical carriers at different wavelengths and are simultaneously sent over asingle fiber. WDM systems are categorized as being coarse or dense,depending on the value of the channel spacing. If the channel spacing is lessthan 1.6 nm (200 GHz), it is termed as Dense WDM (DWDM). Coarse WDM(CWDM) allows wider channel spacing of up to 20 nm. It is very important tomaintain the required level of system performance over a longer transmissiondistance. Today, long haul networks have largely migrated to 10 GbpsDWDM systems with 32 channels or more. The motivation behind choosinglong haul networks is to address the various issues such as fiber losses thatlimit the transmission distance and nonlinear effects that limit the systemperformance. This research work addresses the above limitations for long haulnetwork applications.For long-haul systems, the loss limitation is typically overcome byusing optical amplifiers, which directly amplify the optical signalwithout conversion to electric form. The individual channels of a WDMsignal are amplified simultaneously, and the optical amplifiers reduce theattenuation. Hybrid optical amplifier is an enabling and promising techniquefor DWDM systems to improve output power, gain flatness, etc. newline