Computation and experiments of 10 Gb/s optical access network with long reach and a large number of subscribers

This paper experimentally demonstrates the 10 Gb/s optical access network with downstream transmission at 1550-nm wavelength through a commercial EDFA in order to accomplish the maximum distance of 62 Km over SSMF and 256 subscribers. The theoretical analysis of three effects are considered: (1) link power budget from insertion loss of optical components, fiber´s attenuation and an EDFA´s gain, (2) pulse broadening due to Chromatic Dispersion (CD), and (3) added noises from APD and EDFA. The BER (Bit Error Rate) curves are computed in MATLAB and compared with experimental results when using two optical modulators: (1) EML (Electroabsorption Modulated Laser) with a fixed 8.69-dB Extinction Ratio (ER) and (2) Lithium-Niobate Mach-Zehnder Modulator (MZM) with an adjustable ER between 11.18 - 15.17 dB. Both computed and experimental BER curves prove that a higher ER via MZM gives a better BER than a lower ER fixed by EML. The experimental BER curves of full setup using EML shows its power penalty at BER 10^-12 due to CD and ASE noise to be 0.34 dB and 0.38 dB respectively, whereas the full setup using MZM gives a slightly larger penalty of 0.69 dB and 0.56 dB respectively. Finally, when two TOBPFs (Tunable Optical Band Pass Filter) with 1-nm and 0.25-nm spectral widths are inserted after EDFA, the experimental BER curves show a slight improvement in power penalties of 0.03 dB and 0.15 dB respectively. Evidently, the narrower spectral width can remove ASE noise more effectively.