high pump power and poses safety issues, which is tricky in an access network
environment. SOAs generally have very high noise figure.
3. Downstream optical amplifications can be easily shared amongst multiple
ONUs. However, to share an upstream amplifier could be challenging be-
cause ONUs are located at different distance with different losses to the
optical amplifier. In addition, upstream data are sent in burst mode, requiring
optical amplifier to have fast transient control capabilities.
4. Dispersion effect around 1:5-mm wavelength is nonnegligible. Dispersion
effect increases as the square of bit rate [3]. So without using dispersion-
tolerant transceivers, when both bit rate and distance increases, dispersion
penalty will become significant. ...