WDM Systems in the C-Band Using Er 3+ -Doped Tellurite Optical Waveguide Amplifiers

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Abstract
A 16-channel, 2.5 Gb/s, wavelength-division multiplexing system is analyzed with its channels allocated in the 1.52-1.56 w m wavelength region in order to increase the usable amplifier bandwidth to , 45 nm. To avoid amplified spontaneous emission (ASE) noise and the nonuniform signal gain in the wavelength region, an amplifier module consisting of an Er 3+ -doped tellurite waveguide amplifier, an ASE filter, and two concatenated long-period grating filters are proposed. A tellurite-based amplifier was chosen as the amplifying element because of its broad emission bandwidth (~80 nm), its high emission cross section (6.44 2 10 -25 m 2 ), and its high rare-earth ion solubility. The amplifier model is based on propagation and populationrate equations and includes both uniform and pair-induced up-conversion mechanisms. It is solved numerically by combining finite elements and a Runge-Kutta algorithm. The analysis predicts that using the proposed amplifier module, the channels may be transmitted to a maximum distance of 1800 km, finding applications in large optical networks where either many wavelengths are required or channel spacing must be large.